UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 10-Q

(Mark One)

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2025

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number: 001-41855

Lexeo Therapeutics, Inc.

(Exact Name of Registrant as Specified in its Charter)

Delaware	85-4012572
(State or other jurisdiction of<br>incorporation or organization)	(I.R.S. Employer<br><br>Identification No.)
345 Park Avenue South, Floor 6
---	---
New York, NY	10010
(Address of principal executive offices)	(Zip Code)

(212) 547-9879

(Registrant’s telephone number, including area code)

N/A

(Former name, former address and former fiscal year, if changed since last report)

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol	Name of exchange on which registered
Common Stock ($0.0001 par value)	LXEO	The Nasdaq Global Market

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
Emerging growth company	☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒

The Registrant had 72,987,327 shares of common stock outstanding as of November 3, 2025.

TABLE OF CONTENTS

			Page
	Special Note Regarding Forward Looking Statements		ii
PART I - FINANCIAL INFORMATION			1
	Item 1.	Financial Statements.	1
		Condensed Balance Sheets (unaudited)	2
		Condensed Statements of Operations and Comprehensive Loss (unaudited)	3
		Condensed Statements of Stockholders’ Equity (unaudited)	4
		Condensed Statements of Cash Flows (unaudited)	5
		Notes to Condensed Financial Statements (unaudited)	6
	Item 2.	Management’s Discussion and Analysis of Financial Condition and Results of Operations.	22
	Item 3.	Quantitative and Qualitative Disclosures about Market Risk.	31
	Item 4.	Controls and Procedures.	31
PART II - OTHER INFORMATION			32
	Item 1.	Legal Proceedings.	32
	Item 1A.	Risk Factors.	32
	Item 2.	Unregistered Sales of Equity Securities and Use of Proceeds.	95
	Item 3.	Defaults Upon Senior Securities.	95
	Item 4.	Mine Safety Disclosures.	95
	Item 5.	Other Information.	95
	Item 6.	Exhibits.	96
SIGNATURES			98

-i-

Special Note Regarding Forward Looking Statements

This Quarterly Report on Form 10-Q, or Quarterly Report, contains forward-looking statements that involve risks and uncertainties. We make such forward-looking statements pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. All statements other than statements of historical facts contained in this Quarterly Report, including statements regarding our future results of operations and financial position, business strategy, development plans, planned preclinical studies and clinical trials, future results of clinical trials, expected research and development costs, regulatory strategy, timing and likelihood of success, as well as plans and objectives of management for future operations, are forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “estimate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions intended to identify statements about the future. Forward-looking statements contained in this Quarterly Report include, without limitation, statements about:

• the timing, progress and results of our preclinical studies and clinical trials of our product candidates, including statements regarding the timing of initiation and completion of studies or trials and related preparatory work, the period during which the results of the trials will become available and our research and development programs;

• the timing of our planned investigational new drug, or IND, submissions, initiation of planned clinical trials and timing of expected clinical results for LX2006 and LX2020, if applicable, and our other future product candidates;

• the timing for receipt and announcement of data from our preclinical studies and clinical trials;

• the timing of any submission of filings for regulatory approval of and our ability to obtain and maintain regulatory approvals for LX2006, LX2020 and any other product candidates;

• the impact of public health crises and other adverse global economic conditions on our operations and the potential disruption in the operations and business of third-party manufacturers, contract research organizations, or CROs, other service providers, and collaborators with whom we conduct business;

• our ability to identify patients with the diseases treated by our product candidates, and to enroll patients in trials;

• the beneficial characteristics, safety, efficacy and therapeutic effects of our product candidates;

• the ability of our preclinical studies and clinical trials to demonstrate safety and efficacy of our product candidates, and other positive results;

• our expectations regarding the size of the patient populations, market acceptance and opportunity for and clinical utility of our product candidates, if approved for commercial use;

• our manufacturing capabilities and strategy, including the scalability and commercial viability of our manufacturing methods and processes;

• our reliance on third party manufacturing partners to comply with significant regulations with respect to manufacturing our products;

• our expectations regarding the scope of any approved indication for LX2006, LX2020 or any other product candidate;

• our ability to successfully commercialize our product candidates, if approved;

• our ability to leverage our platform to identify and develop future product candidates;

• our estimates of our expenses, ongoing losses, future revenue, capital requirements and our need for or ability to obtain additional funding before we can expect to generate any revenue from product sales;

• our ability to establish or maintain collaborations or strategic relationships and any expected benefits related thereto;

• our ability to identify, recruit and retain key personnel;

• our reliance upon intellectual property licensed from third parties and our ability to obtain such licenses on commercially reasonable terms or at all;

  -ii-

• our ability to protect and enforce our intellectual property position for our product candidates, and the scope of such protection;

• our financial performance;

• our competitive position and the development of and projections relating to our competitors or our industry;

• our estimates regarding future revenue, expenses and needs for additional financing;

• our anticipated use of our cash, cash equivalents, and investments balances and any proceeds from the ATM Program (as defined below);

• the impact of current and future laws and regulations; and

• our expectations regarding the time during which we will be an emerging growth company under the Jumpstart Our Business Startups Act of 2012, or JOBS Act.

We caution you that the foregoing list does not contain all of the forward-looking statements made in this Quarterly Report. We have based these forward-looking statements largely on our current expectations and projections about our business, the industry in which we operate and financial trends that we believe may affect our business, financial condition, results of operations and prospects, and these forward-looking statements are not guarantees of future performance or development. These forward-looking statements speak only as of the date of this Quarterly Report and are subject to a number of risks, uncertainties and assumptions described in the section titled “Item 1A. Risk Factors” and elsewhere in this Quarterly Report. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. Although we believe that we have a reasonable basis for each forward-looking statement contained in this Quarterly Report, the events and circumstances reflected in our forward-looking statements may not be achieved or occur and actual results could differ materially from those projected in the forward-looking statements. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained herein, whether as a result of any new information, future events or otherwise. In addition, statements that “we believe” and similar statements reflect our beliefs and opinions on the relevant subject. These statements are based upon information available to us as of the date of this Quarterly Report, and while we believe such information forms a reasonable basis for such statements, such information may be limited or incomplete, and our statements should not be read to indicate that we have conducted an exhaustive inquiry into, or review of, all potentially available relevant information. These statements are inherently uncertain, and you are cautioned not to unduly rely upon these statements.

-iii-

Lexeo Therapeutics, Inc.

Condensed Balance Sheets

(Unaudited, in thousands, except share and per share amounts)

			December 31,
			2024
Assets
Current assets:
Cash and cash equivalents	40,996		$	35,014
Current portion of investments in U.S. Treasury securities	81,768			86,504
Prepaid expenses and other current assets	5,029			4,603
Total current assets	127,793			126,121
Non-current portion of investments in U.S. Treasury securities	-			7,012
Long-term investment	3,390			-
Restricted cash	3,248			3,252
Property and equipment, net	1,230			1,028
Lease right-of-use assets - finance	1,220			1,460
Lease right-of-use assets - operating	6,963			8,069
Total assets	143,844		$	146,942
Liabilities and stockholders' equity
Current liabilities:
Accounts payable	4,656		$	6,417
Accrued expenses and other current liabilities	9,900			13,759
Current portion of lease liabilities - finance	568			570
Current portion of lease liabilities - operating	2,147			2,100
Total current liabilities	17,271			22,846
Non-current liabilities
Non-current portion of lease liabilities - finance	454			817
Non-current portion of lease liabilities - operating	5,288			6,437
Total liabilities	23,013			30,100
Commitments and contingencies (Note 11)
Stockholders' equity:
Common stock, 0.0001 par value, 500,000,000 shares authorized as of September 30, 2025; 54,935,477 shares issued and 54,934,275 shares outstanding as of September 30, 2025; 500,000,000 shares authorized as of December 31, 2024; 33,079,209 shares issued and 33,071,261 shares outstanding as of December 31, 2024	5			3
Treasury stock, at cost, 3,827 common shares as of September 30, 2025 and as of December 31, 2024	(17	)		(17	)
Additional paid-in capital	479,969			397,132
Accumulated other comprehensive gain (loss)	89			(103	)
Accumulated deficit	(359,215	)		(280,173	)
Total stockholders' equity	120,831			116,842
Total liabilities and stockholders' equity	143,844		$	146,942

All values are in US Dollars.

The accompanying notes are an integral part of these unaudited condensed financial statements.

Lexeo Therapeutics, Inc.

Condensed Statements of Operations and Comprehensive Loss

(Unaudited, in thousands, except share and per share amounts)

	Three Months Ended September 30,						Nine Months Ended September 30,
	2025			2024			2025			2024
Operating expenses
Research and development	$	15,695		$	23,423		$	47,587		$	55,725
General and administrative		5,953			8,120			38,554			22,659
Total operating expenses		21,648			31,543			86,141			78,384
Operating loss		(21,648	)		(31,543	)		(86,141	)		(78,384	)
Other income and expense
Gain on long-term investment		-			-			3,390			-
Other income (expense), net		(9	)		(3	)		(27	)		(9	)
Interest expense		(22	)		(35	)		(75	)		(107	)
Interest income		1,456			2,092			3,917			6,091
Amortization of premium on investments in U.S. Treasury securities		(60	)		-			(106	)		-
Total other income and expense		1,365			2,054			7,099			5,975
Loss from operations before income taxes		(20,283	)		(29,489	)		(79,042	)		(72,409	)
Income taxes		-			-			-			-
Net loss	$	(20,283	)	$	(29,489	)	$	(79,042	)	$	(72,409	)
Other comprehensive gain
Net unrealized gain on investments		102			-			192			-
Total other comprehensive gain		102			-			192			-
Comprehensive loss	$	(20,181	)	$	(29,489	)	$	(78,850	)	$	(72,409	)
Net loss per common share, basic and diluted	$	(0.33	)	$	(0.89	)	$	(1.72	)	$	(2.31	)
Weighted-average number of shares outstanding used in computation of net loss per common share, basic and diluted		60,980,867			33,063,153			45,991,572			31,354,821

The accompanying notes are an integral part of these unaudited condensed financial statements.

Lexeo Therapeutics, Inc.

Condensed Statements of Stockholders’ Equity

(Unaudited, in thousands, except share amounts)

									Accumulated
							Additional		Other						Total
				Treasury			Paid-in		Comprehensive			Accumulated			Stockholders'
		Amount		Stock			Capital		Income (Loss)			Deficit			Equity
Balances at December 31, 2024	33,071,261	$	3	$	(17	)	$	397,132	$	(103	)	$	(280,173	)	$	116,842
Issuance of common stock upon vesting and settlement of restricted stock units	52,446		-		-			-		-			-			-
Issuance of common stock under 2023 ESPP	65,342		-		-			170		-			-			170
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase	2,816		-		-			13		-			-			13
Unrealized comprehensive gain on investments in U.S. Treasury securities	-		-		-			-		49			-			49
Stock-based compensation expense	-		-		-			3,697		-			-			3,697
Net loss	-		-		-			-		-			(32,656	)		(32,656	)
Balances at March 31, 2025	33,191,865	$	3	$	(17	)	$	401,012	$	(54	)	$	(312,829	)	$	88,115
Issuance of common stock upon vesting and settlement of restricted stock units	14,097		-		-			-		-			-			-
Issuance of common stock, pre-funded warrants and warrants to purchase common stock upon May 2025 Private Placement Offering, net of commissions and offering costs of 6,917	20,790,120		2		-			73,080		-			-			73,082
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase	2,410		-		-			12		-			-			12
Unrealized comprehensive gain on investments in U.S. Treasury securities	-		-		-			-		41			-			41
Stock-based compensation expense	-		-		-			3,071		-			-			3,071
Net loss	-		-		-			-		-			(26,103	)		(26,103	)
Balances at June 30, 2025	53,998,492	$	5	$	(17	)	$	477,175	$	(13	)	$	(338,932	)	$	138,218
Exercise of stock options	9,000		-		-			34		-			-			34
Issuance of common stock upon vesting and settlement of restricted stock units	20,466		-		-			-		-			-			-
Issuance of common stock upon exercise of pre-funded warrants	867,302		-		-			-		-			-			-
Issuance of common stock under 2023 ESPP	37,495		-		-			101		-			-			101
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase	1,520		-		-			8		-			-			8
Unrealized comprehensive gain on investments in U.S. Treasury securities	-		-		-			-		102			-			102
Stock-based compensation expense	-		-		-			2,651		-			-			2,651
Net loss	-		-		-			-		-			(20,283	)		(20,283	)
Balances at September 30, 2025	54,934,275	$	5	$	(17	)	$	479,969	$	89		$	(359,215	)	$	120,831

All values are in US Dollars.

The accompanying notes are an integral part of these unaudited condensed financial statements.

Lexeo Therapeutics, Inc.

Condensed Statements of Stockholders’ Equity

(Unaudited, in thousands, except share amounts)

											Accumulated
								Additional			Other					Total
					Treasury			Paid-in			Comprehensive		Accumulated			Stockholders'
			Amount		Stock			Capital			Income (Loss)		Deficit			Equity
Balances at December 31, 2023	26,646,378		$	3	$	-		$	295,372		$	-	$	(181,840	)	$	113,535
Exercise of stock options	942			-		-			10			-		-			10
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase	1,916			-		-			3			-		-			3
Issuance of common stock upon March 2024 Private Placement Offering, net of commissions and offering costs of 6,246	6,278,905			-		-			88,753			-		-			88,753
Stock-based compensation expense	-			-		-			2,331			-		-			2,331
Net loss	-			-		-			-			-		(21,682	)		(21,682	)
Balances at March 31, 2024	32,928,141		$	3	$	-		$	386,469		$	-	$	(203,522	)	$	182,950
Exercise of stock options	108,912			-		-			419			-		-			419
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase	5,849			-		-			26			-		-			26
Additional offering costs incurred related to issuance of common stock upon private placement offering	-			-		-			(42	)		-		-			(42	)
Treasury stock repurchase	(2,991	)		-		(13	)		-			-		-			(13	)
Stock-based compensation expense	-			-		-			2,846			-		-			2,846
Net loss	-			-		-			-			-		(21,238	)		(21,238	)
Balances at June 30, 2024	33,039,911		$	3	$	(13	)	$	389,718		$	-	$	(224,760	)	$	164,948
Exercise of stock options	15,792			-		-			39			-		-			39
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase	2,744			-		-			14			-		-			14
Additional issuance costs incurred related to issuance of convertible SAFE Note	-			-		-			24			-		-			24
Stock-based compensation expense	-			-		-			3,790			-		-			3,790
Net loss	-			-		-			-			-		(29,489	)		(29,489	)
Balances at September 30, 2024	33,058,447		$	3	$	(13	)	$	393,585		$	-	$	(254,249	)	$	139,326

All values are in US Dollars.

The accompanying notes are an integral part of these unaudited condensed financial statements.

Lexeo Therapeutics, Inc.

Condensed Statements of Cash Flows

(Unaudited, in thousands)

	Nine Months Ended September 30,
	2025			2024
Cash flows from operating activities:
Net loss	$	(79,042	)	$	(72,409	)
Adjustments to reconcile net loss to net cash used in operating activities:
Reduction in the carrying amount of ROU assets, operating		1,106			1,007
Reduction in the carrying amount of ROU assets, finance		240			245
Stock-based compensation expense		9,419			8,967
Depreciation and amortization expense		195			229
Non-cash gain on long-term investment		(3,390	)		-
Amortization of premium on investments in U.S. Treasury securities		106			-
Changes in operating assets and liabilities:
Prepaid expenses and other current assets		(426	)		390
Accounts payable		(1,761	)		4,420
Accrued expenses and other current liabilities		(3,826	)		5,289
Lease liabilities, operating		(1,102	)		(974	)
Lease liabilities, finance		(1	)		11
Net cash used in operating activities		(78,482	)		(52,825	)
Cash flows from investing activities:
Purchase of internal use software		-			(13	)
Purchase of property and equipment		(397	)		(481	)
Purchases of investments		(55,366	)		-
Proceeds from maturities of investments		67,200			-
Net cash provided by (used in) investing activities		11,437			(494	)
Cash flows from financing activities:
Proceeds from exercise of stock options		34			468
Payments on finance leases		(364	)		(294	)
Proceeds from common stock issuances under 2023 ESPP		271			-
Treasury stock repurchase		-			(13	)
Proceeds from issuance of common stock upon March 2024 Private Placement Offering		-			94,999
Third-party commissions and offering costs incurred upon March 2024 Private Placement Offering		-			(6,287	)
Proceeds from issuance of common stock, pre-funded warrants and warrants to purchase common stock upon May 2025 Private Placement Offering		79,999			-
Third-party commissions and offering costs incurred upon May 2025 Private Placement Offering		(6,917	)		-
Net cash provided by financing activities		73,023			88,873
Net change in cash, cash equivalents and restricted cash		5,978			35,554
Cash, cash equivalents and restricted cash at beginning of period		38,266			124,718
Cash, cash equivalents and restricted cash at end of period	$	44,244		$	160,272
Supplemental disclosure of non-cash activities
Unrealized gain on investments	$	192		$	-
Net property and equipment purchased in the current period included in accounts payable (net property and equipment purchased in the prior period previously included in accounts payable and paid in the current period)	$	-		$	(141	)
Finance lease right-of use assets and finance lease liabilities recognized	$	-		$	22
Amounts reclassified from deposit liabilities upon the vesting of early-exercised stock options previously subject to repurchase, net of proceeds received from early exercise of unvested stock options subject to repurchase and recorded as deposit liabilities	$	33		$	42

The accompanying notes are an integral part of these unaudited condensed financial statements.

Lexeo Therapeutics, Inc.

Notes to Condensed Financial Statements

(Unaudited, table amounts in thousands, except share, per share, year, and percentage amounts)

1. Description of Business and Basis of Presentation

Description of Business—Lexeo Therapeutics, Inc. (the “Company”) is a clinical stage genetic medicine company dedicated to pioneering novel treatments for cardiovascular disease. The Company utilizes adeno-associated viruses (“AAV”) that have been engineered to transfer genes to patients. The Company’s therapeutic investigational treatments include AAV-based gene therapies primarily in the clinical and late pre-clinical stages of research and development.

The Company is located in New York, NY and was first formed on February 17, 2017, as an LLC under the laws of the State of Delaware under the legal name Lexeo Therapeutics, LLC. The Company filed and executed a certificate of conversion to corporation on November 20, 2020, to convert the LLC to Lexeo Therapeutics, Inc., a Delaware corporation. All of the Company’s tangible assets are held in the United States (“U.S.”).

Basis of Presentation and Principles of Consolidation—The Company’s fiscal year ends on December 31, and its fiscal quarters end on March 31, June 30, and September 30.

These unaudited condensed financial statements and these notes reflect the operations of the Company that have been prepared in conformity with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. These unaudited condensed financial statements and accompanying notes should be read in conjunction with the Company’s audited financial statements and notes thereto for the year ended December 31, 2024 (the “Annual Financial Statements”) included in the Company's Annual Report on Form 10-K, filed with the United States Securities and Exchange Commission on March 24, 2025. The unaudited condensed balance sheet at December 31, 2024 has been derived from the audited financial statements at that date. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary to present fairly the financial position of the Company and its results of operations and cash flows for the periods presented have been included. Operating results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025, for any other interim period, or for any other future year.

Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”). The Company has no unconsolidated subsidiaries. Certain prior period balances have been reclassified to conform to the current period presentation.

Need for Additional Capital—Since inception, the Company has incurred net losses and negative cash flows from operations, including net losses of $79.0 million and $98.3 million during the nine months ended September 30, 2025 and the year ended December 31, 2024, respectively. As of September 30, 2025, the Company had cash, cash equivalents, and investments in U.S. Treasury securities of $122.8 million and an accumulated deficit of $359.2 million and expects to incur substantial operating losses and negative cash flows from operations for the foreseeable future. During the nine months ended September 30, 2024, the Company received total net proceeds of $88.8 million after deducting approximately $6.2 million of commissions and offering expenses in the March 2024 Private Placement (as defined below) (see Note 8). During the nine months ended September 30, 2025, the Company received total net proceeds of approximately $73.1 million after deducting approximately $6.9 million of commissions and offering expenses in the May 2025 Private Placement (as defined below) (see Note 8). In October 2025, the Company received total estimated net proceeds of approximately $143.9 million after deducting approximately $9.9 million of underwriter commissions, placement agent fees and estimated offering expenses in the October 2025 Financing Transactions (as defined below) (see Note 14). Management estimates that the Company's current cash, cash equivalents, and investments in U.S. Treasury securities balances are sufficient to fund its operations for at least 12 months from the issuance date of these financial statements.

If the Company is unable to obtain additional funding before achieving sufficient profitability and positive cash flows from operations, if ever, the Company will be forced to delay, reduce or eliminate some or all of its research and development programs, which could adversely affect its business prospects, or the Company may be unable to continue operations. Although management continues to pursue plans to obtain additional funding before achieving sufficient profitability and positive cash flows from operations, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all.

Risks and Uncertainties—The Company is subject to risks and uncertainties common to early-stage companies in the biopharmaceutical industry, including, but not limited to, successful discovery and development of its product candidates, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, protection of proprietary technology, compliance with governmental regulations, the ability to secure additional capital to fund operations, and commercial success of its product candidates. Any of the Company’s current product candidates and future product candidates that it may develop will require extensive non-clinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel, infrastructure, and extensive compliance- reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

2. Summary of Significant Accounting Policies

There have been no significant changes in the Company’s accounting policies from those disclosed in its Annual Financial Statements. Use of Estimates—The preparation of the financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of income and expense during the reporting period. The most significant estimates relate to the accruals of research and development costs, including accruals of research contract costs, and assumptions used to estimate the fair value of the Company’s stock option awards and, prior to the closing of its initial public offering ("IPO") on November 7, 2023, to determine the fair value of its common stock. Management evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the current economic environment, and makes adjustments when facts and circumstances dictate. These estimates are based on information available as of the date of the financial statements; therefore, actual results could differ from those estimates. Net Loss per Share—The Company follows the two-class method when computing net income (loss) per common share as the Company has issued shares that meet the definition of participating securities. The two-class method determines net income (loss) per common share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires income (loss) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to receive dividends as if all income for the period had been distributed. The Company considers the shares issued upon the early exercise of stock options that are subject to repurchase to be participating securities because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. There is no allocation required under the two-class method during periods of loss since the participating securities do not have a contractual obligation to share in the losses of the Company.

Basic net income (loss) per common share is computed by dividing the net income (loss) per common share by the weighted-average number of common shares and pre-funded warrants to purchase shares of common stock outstanding for the period. In accordance with ASC Topic 260, Earnings per Share, the pre-funded warrants are included in the computation of basic net loss per share because the exercise price is negligible and they are fully vested and exercisable at any time after the original issuance date. Diluted net income (loss) per common share is computed by adjusting net income (loss) to reallocate undistributed earnings based on the potential impact of dilutive securities. Diluted net loss per common share is computed by dividing the diluted net loss by the weighted-average number of common shares outstanding for the period, including potential dilutive common shares.

In periods in which the Company reported a net loss, diluted net loss per common share was the same as basic net loss per common share since dilutive common shares were not assumed to have been issued if their effect was anti-dilutive. During the three and nine months ended September 30, 2025 and September 30, 2024, 19,295,632 (for each of the periods in 2025) and 3,744,541 (for each of the periods in 2024) total potential common shares, respectively, related to the exercise of outstanding stock options, settlement of outstanding restricted stock units ("RSUs"), settlement of outstanding RSUs that vest upon the achievement of certain performance conditions ("PRSUs"), and exercise of outstanding warrants were excluded from the computation of diluted net loss per common share because including them would have had an anti-dilutive effect as the Company reported net losses for those periods.

Stock Based Compensation Expense—The Company accounts for stock-based payment awards granted to employees and non-employees, as well as shares issued to its employees under the Company's 2023 Employee Stock Purchase Plan (the "2023 ESPP"), as stock-based compensation expense at fair value. The Company issues stock-based awards to employees and non-employees in the form of stock options and also issues stock-based awards to employees in the form of RSUs and PRSUs. The measurement date for employee stock option, RSU, and PRSU awards is the date of grant, and stock-based compensation costs for employee non-performance awards are recognized as expense over the employees’ requisite service period, which is the vesting period, on a graded basis. Compensation expense for equity awards with performance conditions, including PRSUs, is recognized if and when the Company concludes that it is probable that the performance conditions will be achieved. The Company reassesses the probability of vesting at each reporting period for equity awards with such performance conditions and adjusts compensation expense based on its probability assessment. The measurement date for non-employee awards is the date of grant without changes in the fair value of the award, and stock-based compensation costs for non-employees are recognized as expense over the vesting period on a graded basis. The measurement date for shares issued under the 2023 ESPP is the first date of each employee stock purchase plan offering period, and stock-based compensation costs are recognized as expense over the offering period on a straight-line basis. Stock-based compensation expense for all equity awards is classified in the accompanying statement of operations based on the function to which the related services are provided. As the Company is permitted to repurchase shares legally issued for unvested stock options exercised at their exercise price under the Company's 2021 Equity Incentive Plan (the "2021 Plan"), (i) cash received for unvested stock options exercised under the 2021 Plan is recorded as a deposit liability as a reclassification from additional paid-in capital in the Company’s balance sheet, which is relieved to additional paid-in capital as such awards vest, (ii) stock based compensation expense is recognized over the requisite service period for each such award, and (iii) the amount and number of shares of common stock outstanding in the Company’s balance sheet and statement stockholders’ equity are reduced until such awards vest. Forfeitures are recorded as they occur.

The fair value of each stock option grant under the 2021 Plan and the Company's 2023 Equity Incentive Plan (the "2023 Plan", and together with the 2021 Plan, the “Plans”), and shares issued under the 2023 ESPP, are estimated on the date of stock option grant or on the first date of each employee stock purchase plan offering period, respectively, using the Black-Scholes option-pricing model, while the fair value of each RSU and PRSU granted under the 2023 Plan is equal to the closing price of the Company's common stock on the date of the grant. Prior to its IPO on November 3, 2023, the Company was a private company and lacked company-specific historical and implied volatility information for stock options granted. Therefore, the Company estimated its expected stock volatility entirely based on the historical volatility of a publicly traded set of peer companies for stock options granted prior to its IPO, and estimates its expected stock price volatility primarily based on the historical volatility of a publicly traded set of peer companies for stock options granted since its IPO, each for a period equal to the expected life of the stock options granted, and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options granted has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options and expects to continue to do so until such time as it has adequate historical data regarding the expected term of its own stock options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The expected dividend yield is zero as the Company has never paid cash dividends on its common stock and does not expect to pay any cash dividends in the foreseeable future. Long-term Investment—The Company accounts for its long-term investment in nonredeemable convertible preferred stock in accordance with the provisions of ASC Topic 321, Investments - Equity Securities, and elected to use the measurement alternative therein. The fair value of the nonredeemable convertible preferred stock received was based upon an observable price of cash paid for an identical security in an orderly transaction with a third-party and was capitalized as a long-term investment in the Company's balance sheet and recorded as an unrealized gain to other non-operating income in the Company's statement of operations and comprehensive loss. The long-term investment will be remeasured upon future observable price change(s) in orderly transaction(s) or upon impairment, if any.Concentrations of Credit Risk—Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, restricted cash, and investments. The Company’s cash and restricted cash balances exceed Federal Deposit Insurance Corporation insurance limits. The Company’s cash equivalents consist of investments in U.S. government money market funds, and the Company's cash investments consist of U.S. Treasury securities. The Company’s cash, cash equivalents, and restricted cash are held with large financial institutions that management believes to be of high credit quality. To date, the Company has not recognized any losses caused by uninsured balances.

3. Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The three levels of inputs that may be used to measure fair value are as follows:

Level 1—Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

Level 2—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities.

Level 3—Inputs are unobservable inputs for the asset or liability.

The Company’s cash equivalents consist of investments in U.S. government money market funds stated at carrying value, which approximates fair value and is based on quoted prices in active markets for identical securities. Cash is stated at carrying value, which approximates fair value due to its short-term nature. The Company classifies its investments in U.S. Treasury securities as Level 2 assets as these assets are not traded in an active market and have been valued through a third-party pricing service based on quoted prices for similar assets. The carrying values of the Company’s prepaid expenses, other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term nature.

The following table presents information about the Company’s financial assets and investments measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values:

	As of September 30, 2025:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents (money market)	$	18,420	$	-	$	-	$	18,420
Current portion of investments in U.S. Treasury securities		-		81,768		-		81,768
Investments:
Non-current portion of investments in U.S. Treasury securities		-		-		-		-
	$	18,420	$	81,768	$	-	$	100,188
	As of December 31, 2024:
---	---	---	---	---	---	---	---	---
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents (money market)	$	17,636	$	-	$	-	$	17,636
Current portion of investments in U.S. Treasury securities		-		86,504		-		86,504
Investments:
Non-current portion of investments in U.S. Treasury securities		-		7,012		-		7,012
	$	17,636	$	93,516	$	-	$	111,152

Investments in U.S. Treasury securities, which are classified as available-for-sale securities, consisted of the following as of September 30, 2025 and December 31, 2024:

	As of September 30, 2025:
	Amortized Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Available-for-sale securities:
U.S. Treasury securities	$	81,679	$	89	$	-	$	81,768
	$	81,679	$	89	$	-	$	81,768
	As of December 31, 2024:
---	---	---	---	---	---	---	---	---	---
	Amortized Cost Basis		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available-for-sale securities:
U.S. Treasury securities	$	93,619	$	-	$	(103	)	$	93,516
	$	93,619	$	-	$	(103	)	$	93,516

All investments in U.S. Treasury securities classified as available-for-sale securities held as of September 30, 2025 and December 31, 2024 had contractual maturities of less than two years. There have been no material realized gains or losses on investments classified as available-for-sale securities for the periods presented. Aggregate fair values of investments in U.S. Treasury securities classified as available-for-sale securities with unrealized losses and gains were as follows as of September 30, 2025 and December 31, 2024:

	September 30, 2025		December 31, 2024
Available-for-sale securities:
Due within one year	$	81,768	$	86,504
Due after one year through five years		-		7,012
	$	81,768	$	93,516

4. Property and Equipment

The following is the summary of the Company’s property and equipment and related accumulated depreciation as of September 30, 2025 and December 31, 2024:

	Useful Life	September 30, 2025			December 31, 2024
Furniture and fixtures	5 years	$	386		$	386
Lab equipment	7 years		1,240			844
Leasehold improvements	7 years		272			272
Total property and equipment			1,898			1,502
Less: accumulated depreciation			(668	)		(474	)
Total property and equipment, net		$	1,230		$	1,028

5. Long-term Investment

In June 2025, the Company entered into a collaboration and license agreement (the "June 2025 CLA") and a preferred stock purchase agreement (the "June 2025 Preferred Stock Purchase Agreement") with a privately-held Delaware corporation (the "Investee"). In exchange for access to certain of the Company's technology, intellectual property, and know-how granted to the Investee under the terms of the June 2025 CLA, the Company received 10,000,000 shares of the Investee's nonredeemable convertible preferred stock issued under the June 2025 Preferred Stock Purchase Agreement, initially representing approximately 12% of the Investee's issued and outstanding voting stock as of June 30, 2025. Under the terms of the June 2025 CLA, the Company is entitled to certain future milestone payments, royalties, and opt-in rights to certain program(s).

The Company accounts for its investment in the Investee in accordance with the provisions of ASC Topic 321, Investments - Equity Securities, and elected to use the measurement alternative therein. The fair value of the nonredeemable convertible preferred stock received of approximately $3.4 million, or approximately $0.338983 per share, was based upon an observable price of cash paid for an identical security in an orderly transaction between the Investee and a third-party and was capitalized as a long-term investment in the Company's balance sheet and recorded as an unrealized gain to other non-operating income in the Company's statement of operations and comprehensive loss. The long-term investment will be remeasured upon future observable price change(s) in orderly transaction(s) or upon impairment, if any.

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:

	September 30, 2025		December 31, 2024
Accrued research and development expenses	$	6,166	$	6,696
Accrued compensation and other personnel costs		2,982		4,112
Accrued general and administrative expenses and other professional fees		543		2,406
Other current liabilities		209		545
Total accrued expenses and other current liabilities	$	9,900	$	13,759

7. Leases

Operating Lease Right-of-Use Asset

In January 2022, the Company entered into a lease agreement for an office facility and laboratory space in New York, New York that commenced in April 2022 and ends in July 2029 with an additional five-year option to extend the lease beyond July 2029 at the then-prevailing effective market rental rate. Upon commencement of this lease, the Company recorded operating lease right-of-use assets and operating lease liabilities of $11.6 million based on the present value of payments over the lease term using an estimated incremental borrowing rate of 8.53% in accordance with the provisions of ASC Topic 842, Leases (“ASC 842”). In connection with the Company’s lease of office space and laboratory space, the Company provided a security deposit to the landlord in the form of a letter of credit totaling $1.2 million. The cash collateralizing the letter of credit was included in long-term restricted cash in the Company’s condensed balance sheets as of September 30, 2025 and December 31, 2024. This lease was classified as an operating lease in accordance with the provisions of ASC 842. The Company did not recognize any right-of-use assets and lease liabilities associated with the potential option to renew or extend. The Company’s operating lease agreement does not contain any significant residual value guarantees or restrictive covenants.

The remaining lease terms and payment terms as of September 30, 2025 and December 31, 2024 were

3.8

years and

4.6

years, respectively. The components of this operating lease were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2025		2024		2025		2024
Operating lease expense	$	541	$	537	$	1,606	$	1,611
Variable lease expense		126		116		377		344
Total operating lease expense	$	667	$	653	$	1,983	$	1,955
Cash paid for amounts included in the measurement of lease liabilities, included in operating cash flows	$	537	$	528	$	1,610	$	1,578

The following table provides a reconciliation of the Company’s remaining undiscounted contractual rent obligations due within each year ended December 31 to the operating lease liabilities recognized as of September 30, 2025:

Year ended December 31	Operating<br>Leases
2025	$	545
2026		2,206
2027		2,261
2028		2,318
2029		1,372
Thereafter		-
Total lease payments		8,702
Less: present value adjustment		(1,267	)
Total operating lease liabilities	$	7,435
Included in the balance sheet:
Current portion of lease liabilities - operating	$	2,147
Non-current portion of lease liabilities - operating		5,288
Total operating lease liabilities	$	7,435

Equipment Finance Leases

Commencing in April 2022, the Company leases certain laboratory equipment under financing arrangements accounted for as finance leases in accordance with the provisions of ASC 842 that are classified in the Company’s condensed balance sheet as finance lease liabilities with related right-of-use assets recorded and depreciated on a straight-line basis over the estimated useful life of 7 years. In connection with the Company’s leases of laboratory equipment, the Company provided a security deposit to the lessor in the form of a letter of credit totaling $1.9 million and assigned all rights and interests in the equipment to the lessor. The cash collateralizing the letter of credit is included in long-term restricted cash in the Company’s condensed balance sheet as of September 30, 2025. The total gross, accumulated amortization, and net book values of equipment finance lease right-of-use assets capitalized under such finance lease arrangements at September 30, 2025 were $2.2 million, $1.0 million and $1.2 million, respectively. Under the terms of the equipment finance lease agreements executed through the issuance of these unaudited condensed financial statements, the principal balances plus interest for the equipment are to be repaid in full after 60 monthly installments following lease commencement, with lease commencement dates ranging from April 1, 2022 to April 1, 2023, annual imputed interest rates ranging from 7.90% to 9.30%, and monthly installment payment amounts ranging from approximately $4,000 to $18,000. As of September 30, 2025, the total aggregate monthly installment payment amount was approximately $49,000 for equipment finance lease agreements.

The weighted-average remaining lease payment term, weighted-average remaining amortization term, and weighted-average effective interest rate for the Company's equipment finance lease agreements as of September 30, 2025 were

1.9

years,

4.1

years, and 8.60%, respectively. The weighted-average remaining lease payment term, weighted-average remaining amortization term, and weighted-average effective interest rate for the Company's equipment finance lease agreements as of December 31, 2024 were

2.7

years,

4.8

years, and 8.59%, respectively. The components of the equipment finance leases were as follows:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2025		2024		2025		2024
Reduction in the carrying amount of ROU assets, finance	$	80	$	80	$	240	$	245
Interest on finance lease liabilities		15		36		77		96
Total finance lease expense	$	95	$	116	$	317	$	341
Cash paid for amounts included in the measurement of lease liabilities, included in financing cash flows	$	83	$	111	$	364	$	294

The following table provides a reconciliation of the Company’s remaining equipment finance lease obligations due within each year ending December 31 to the equipment finance lease liabilities recognized at September 30, 2025:

Year ended December 31	Equipment Finance Leases
2025	$	147
2026		587
2027		359
2028		11
2029		-
Thereafter		-
Total lease payments		1,104
Less: imputed interest		(82	)
Total finance lease liabilities	$	1,022
Included in the balance sheet:
Current portion of lease liabilities - finance	$	568
Non-current portion of lease liabilities - finance		454
Total finance lease liabilities	$	1,022

8. Capital Stock

As of September 30, 2025 and December 31, 2024, the Company’s amended and restated certificate of incorporation provided that the authorized capital stock of the Company was 510,000,000 shares consisting of 500,000,000 shares of common stock and 10,000,000 shares of undesignated preferred stock, both with a par value of $0.0001 per share. As of September 30, 2025 and December 31, 2024, 54,935,477 shares and 33,079,209 shares, respectively, of the Company's common stock authorized were issued, including 1,202 shares and 7,948 shares, respectively, that were legally issued upon the early exercise of unvested stock options and that are excluded from the number of shares outstanding until the right to repurchase subsequently lapses upon vesting. The Company did not repurchase any shares of its common stock during the three and nine months ended September 30, 2025, and repurchased a total of 3,827 shares of its common stock issued pursuant to the early exercise of stock options granted under the 2021 Plan for a total of approximately $17,000 during the year ended December 31, 2024, which was recorded to treasury stock in the Company's balance sheet (see Note 9). Each common share entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, if any, as may be declared by the Company’s Board of Directors. No cash dividends have been declared or paid by the Company.

On March 11, 2024, the Company entered into a common stock purchase agreement to issue and sell an aggregate of 6,278,905 shares of its common stock at a price of $15.13 per share, in a private placement that closed on March 13, 2024 (the "March 2024 Private Placement"). The gross and net proceeds received from the March 2024 Private Placement were approximately $95.0 million and $88.8 million, respectively, after deducting approximately $6.2 million of commissions and other offering costs.

On March 24, 2025, the Company entered into a sales agreement (the "Sales Agreement") with Leerink Partners LLC ("Leerink") to sell shares of the Company's common stock having an aggregate offering price of up to $75.0 million from time to time through an at-the-market equity offering program (the "ATM Program") under which Leerink is acting as the Company's agent. Leerink is entitled to compensation for its services in an amount equal to 3% of the gross proceeds of any of the shares of the Company's common stock sold under the Sales Agreement. No shares of the Company's common stock have been sold under the Sales Agreement through September 30, 2025.

On May 28, 2025, pursuant to a securities purchase agreement, the Company issued and sold an aggregate of 20,790,120 shares of its common stock, as well as pre-funded warrants to purchase 6,963,556 shares of its common stock to certain purchasers, together with accompanying warrants to purchase 13,876,838 shares of its common stock, at a purchase price of $2.8825 per share of common stock and accompanying common warrant, or $2.8824 per pre-funded warrant and accompanying warrant (the "May 2025 Private Placement"). The gross and net proceeds received from the May 2025 Private Placement were approximately $80.0 million and $73.1 million, respectively, after deducting approximately $6.9 million of commissions and other offering costs. The warrants and pre-funded warrants issued in the May 2025 Private Placement are immediately exercisable at exercise prices of $2.82 per share and $0.0001 per share, respectively, except that the warrants and pre-funded warrants cannot be exercised by the holder if, after giving effect thereto, the holder would beneficially own more than 9.99% of the Company’s common stock (the "Maximum Percentage"). The Maximum Percentage can be changed at the holder's election to any other percentage not in excess of 19.99%, and any increase in the Maximum Percentage will not be effective until the 61st day after the holder provides notice to the Company of the desired increase. The warrants are exercisable until May 28, 2029, and the pre-funded warrants do not expire. The warrants and pre-funded warrants are classified as equity in accordance with ASC Topic 815-40, Derivatives and Hedging - Contracts in an Entity's Own Equity. Upon issuance, the total pre-allocated fair value of the warrants of approximately $26.8 million, or approximately $1.93 per warrant share, was estimated using a Black-Scholes option pricing model with the following assumptions:

Stock Price	$	2.74
Exercise Price	$	2.82
Risk-free interest rate		4.00	%
Expected term (in years)		4.00
Expected volatility		100.35	%
Expected dividend yield		0.00	%

Approximately $44.3 million, $20.8 million and $14.9 million of the total gross proceeds received in the May 2025 Private Placement were allocated to the shares of common stock, warrants and pre-funded warrants, respectively, on a relative fair value basis, and were recorded as credits to additional paid-in capital, and are not subject to remeasurement. As of September 30, 2025, none of the warrants and 867,302 pre-funded warrants issued had been exercised.

The Company had reserved the following number of shares of common stock for the exercise of outstanding warrants, exercise of outstanding pre-funded warrants, exercise of outstanding stock options, settlement of outstanding RSUs and PRSUs, and future issuances of stock-based awards:

	September 30, 2025		December 31, 2024
Warrants to purchase shares of common stock		13,876,838		-
Pre-funded warrants to purchase shares of common stock		6,096,254		-
Options to purchase shares of common stock under the 2021 Plan and 2023 Plan		4,476,094		3,457,918
RSUs and PRSUs subject to settlement in shares of common stock under the 2023 Plan		942,700		266,300
Shares available for issuance under the 2023 Plan		2,052,039		2,185,328
Shares available for issuance under the 2023 ESPP		733,239		505,284
Total shares of common stock reserved for future issuance		28,177,164		6,414,830

In October 2025, the Company received total estimated net proceeds of approximately $143.9 million after deducting approximately $9.9 million of underwriter commissions, placement agent fees and estimated offering expenses upon the issuance of an aggregate total of 17,968,750 shares of the Company's common stock and pre-funded warrants to purchase 1,250,015 shares of its Common stock in the October 2025 Financing Transactions (as defined below) (see Note 14).

9. Stock-based Compensation

In February 2021, the Company adopted the 2021 Plan for the issuance of stock options granted to the Company’s key directors, officers, employees and consultants, as a means to secure the benefits arising from capital stock ownership. In connection with the Company’s IPO in November 2023, the Company adopted the 2023 Plan for the issuance of equity awards granted to the Company's directors, officers, employees, and consultants, and for the issuance of shares purchased under the 2023 ESPP to the Company's employees, as a means to secure the benefits arising from capital stock ownership. The purposes of the Plans and the 2023 ESPP are also to promote the alignment of the interests of directors, officers, employees, and consultants with the success of the Company and to provide compensation opportunities to attract, retain and motivate directors, officers, employees, and consultants of the Company. Upon adoption of the 2023 Plan, no further grants may be made under the 2021 Plan.

The number of shares of common stock reserved for issuance under the 2023 Plan will automatically increase on January 1 of each year, beginning on January 1, 2024, and continuing through and including January 1, 2033, by 5% of the total number of shares of common stock outstanding on December 31 of the immediately preceding calendar year, or a lesser number of shares determined by the Company’s Board of Directors prior to the applicable January 1. The number of shares of common stock reserved for issuance under the 2023 ESPP will automatically increase on January 1 of each calendar year, beginning on January 1, 2024 and continuing through and including January 1, 2033, by the lesser of (i) 1% of the total number of shares of capital stock outstanding on December 31 of the preceding calendar year, (ii) 477,200 shares, and (iii) a number of shares determined by the Company’s Board of Directors. Shares subject to purchase rights granted under the 2023 ESPP that terminate without having been exercised in full do not reduce the number of shares available for issuance under the 2023 ESPP.

On January 1, 2025, the number of shares of common stock reserved for issuance under the 2023 Plan and the 2023 ESPP automatically increased by 1,653,960 shares and 330,792 shares, respectively, to totals of 7,724,384 shares and 836,076 shares, respectively. As of September 30, 2025, 2,052,039 shares and 733,239 shares were available for future issuance under the 2023 Plan and 2023 ESPP, respectively. A total of 102,837 shares have been issued under the 2023 ESPP through September 30, 2025.

On November 4, 2025, the Company's board of directors adopted the Lexeo Therapeutics, Inc. 2025 Inducement Equity Incentive Plan (the "2025 Inducement Equity Plan") and, subject to the adjustment provisions of the 2025 Inducement Equity Plan, reserved 2,000,000 shares of the Company's common stock for issuance pursuant to equity awards granted under the 2025 Inducement Equity Plan (see Note 14).

Stock option activity

Stock options granted under the 2021 Plan are issued from new shares upon exercise, have a contractual term of 10 years from grant date, and generally (i) are subject to requisite service requirements, (ii) vest over a four-year period with 25% of the options granted vesting after one year and the remainder vesting in equal monthly installments over the following 36 months, and (iii) allow for early exercise subject to repurchase. Stock options granted under the 2021 Plan to certain of the Company’s non-employees vest in equal monthly installments over a four-year period or vested upon the achievement of a certain milestone event. The Company did not repurchase any shares of its common stock during the three and nine months ended September 30, 2025, and repurchased a total of 3,827 shares of its common stock issued pursuant to the early exercise of stock options granted under the 2021 Plan for a total of approximately $17,000 during the year ended December 31, 2024, which was recorded to treasury stock in the Company's balance sheet (see Note 8).

Stock options granted under the 2023 Plan are issued from new shares upon exercise, have a contractual term of 10 years from grant date, and generally vest over a four-year period with 25% of the options granted vesting after approximately one year and the remainder vesting in equal monthly installments over the following 36 months, subject to requisite service requirements. Stock options granted under the 2023 Plan to certain of the Company's non-employee directors vest in equal annual installments over a three-year period for initial grants or over a one-year period for subsequent annual grants, subject to requisite service requirements.

The following table summarizes the stock option activity under the 2021 Plan and the 2023 Plan for the nine months ended September 30, 2025:

	Number of			Weighted-<br>Average<br>Exercise Price		Weighted-<br>Average<br>Remaining<br>Contractual<br>Term		Aggregate<br>Intrinsic
	Shares			(per share)		(in years)		Value
Outstanding as of December 31, 2024		3,457,918		$	11.37		8.18	$	2,851
Granted		1,450,904			5.57
Exercised		(9,000	)		3.74				27
Forfeited		(409,195	)		8.26
Expired		(14,533	)		13.00
Outstanding as of September 30, 2025		4,476,094		$	9.74		8.04	$	705
Options exercisable at September 30, 2025		2,473,302		$	9.79		6.93	$	2,941

The weighted-average grant date fair value of stock options granted during the nine months ended September 30, 2025 and September 30, 2024 was $4.22 per share and $11.78 per share, respectively.

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock. The total aggregate intrinsic value of stock options exercised during the nine months ended September 30, 2025 and September 30, 2024 were $27,000 and $1.2 million, respectively.

The total grant date fair values of stock options vested during the three months ended September 30, 2025 and September 30, 2024 were $2.1 million and $1.3 million, respectively. The total grant date fair values of stock options vested during the nine months ended September 30, 2025 and September 30, 2024 were $9.1 million and $2.9 million, respectively.

The Company estimated the fair value of options granted using a Black-Scholes option pricing model with the following assumptions presented on a weighted-average basis during the nine months ended September 30, 2025 and September 30, 2024:

	Nine Months Ended
	September 30,
	2025			2024
Risk-free interest rate		4.25	%		4.14	%
Expected term (in years)		5.79			6.02
Expected volatility		92.25	%		85.78	%
Expected dividend yield		0.00	%		0.00	%

The expected dividend yields are 0.00% as the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.

As of September 30, 2025 there was $9.5 million of unrecognized stock-based compensation expense related to stock options estimated to be recognized over a weighted-average period of

2.40

years.

RSU and PRSU activity

RSUs granted under the 2023 Plan generally vest over a four-year period with 25% of the RSUs vesting after approximately one year and the remainder vesting in equal quarterly installments over the following 12 quarters, subject to requisite service requirements. During the nine months ended September 30, 2025, a total of 217,500 PRSUs were granted to certain employees under the 2023 Plan that vest upon the achievement of certain performance conditions generally over an approximate 18-month period, subject to requisite service requirements. Additionally, during the nine months ended September 30, 2025, a total of 77,650 RSUs were granted to employees under the 2023 Plan that vest over a two-year period with 50% of the RSUs vesting after approximately one year and the remainder vesting in equal quarterly installments over the following four quarters, subject to requisite service requirements.

The following table summarizes the RSU activity under the 2023 Plan for the nine months ended September 30, 2025:

	Number of			Weighted-<br>Average<br>Grant Date Fair Value
	Shares			(per share)
Unvested as of December 31, 2024		266,300		$	15.59
Granted		664,684			5.45
Vested		(87,009	)		15.54
Forfeited		(118,775	)		7.58
Unvested as of September 30, 2025		725,200		$	7.61

The following table summarizes the PRSU activity under the 2023 Plan for the nine months ended September 30, 2025:

	Number of		Weighted-<br>Average<br>Grant Date Fair Value
	Shares		(per share)
Unvested as of December 31, 2024		-	$	-
Granted		217,500		7.25
Vested		-		-
Forfeited		-		-
Unvested as of September 30, 2025		217,500	$	7.25

As of September 30, 2025 there was $4.2 million of unrecognized stock-based compensation expense related to RSUs and PRSUs estimated to be recognized over a weighted-average period of

2.92

years.

Employee Stock Purchase Plan

Under the 2023 ESPP, eligible employees may purchase shares of the Company's common stock through payroll deductions at a price equal to 85% of the lower of the fair market values of the stock as of the beginning of the offering period or the end of each six-month purchase period. Each offering period of two years will consist of four six-month purchase periods, subject to reset on the first day of each purchase period depending on the fair market values of the Company's stock. Employees may not purchase more than 6,000 shares of the Company's common stock during any purchase period. The first purchase period within the first offering period under the 2023 ESPP commenced during the three months ended December 31, 2024 and concluded during the three months ended March 31, 2025; following reset, the first purchase period within the second offering period commenced during the three months ended March 31, 2025 and concluded during the three months ended September 30, 2025; and the second purchase period within the second offering period commenced during the three months ended September 30, 2025. As of and during the three and nine months ended September 30, 2025, stock-based compensation expense recorded, as well as the estimated fair value of unearned and unrecognized stock-based expense expected to be recorded, related to the 2023 ESPP were not material. During the nine months ended September 30, 2025, a total of 102,837 shares were issued under the 2023 ESPP at a weighted average purchase price of $2.62 per share with total proceeds of approximately $0.3 million received by the Company.

Stock-based compensation expense

Stock-based compensation expense was classified as follows in the Company’s unaudited condensed statements of operations and comprehensive loss:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2025		2024		2025		2024
Research and development expense	$	1,435	$	1,817	$	4,700	$	4,337
General and administrative expense		1,216		1,973		4,719		4,630
Total stock-based compensation expense	$	2,651	$	3,790	$	9,419	$	8,967

10. Net Loss per Share

Basic and diluted net loss per common share attributable to common stockholders was calculated as follows:

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2025			2024			2025			2024
Numerator:
Net loss attributable to common stockholders	$	(20,283	)	$	(29,489	)	$	(79,042	)	$	(72,409	)
Denominator:
Weighted-average common shares outstanding, basic and diluted		60,980,867			33,063,153			45,991,572			31,354,821
Net loss per share attributable to common stockholders, basic and diluted	$	(0.33	)	$	(0.89	)	$	(1.72	)	$	(2.31	)

11. Commitments and Contingencies

Leases—As of September 30, 2025, the Company had entered into commitments under lease agreements to rent laboratory and office space and finance equipment (see Note 7).

Commitments—As of September 30, 2025, the Company had entered into commitments under license, acquisition, research collaboration and sponsored research agreements with third parties (see Note 12). In addition, the Company has entered into services agreements with third parties for pharmaceutical manufacturing and research activities in the normal course of business, which can generally be terminated by the Company with 30- to 60-days’ written notice, unless otherwise indicated. Further, certain of the Company’s manufacturing agreements could require early termination and wind-down payments due from the Company upon either the termination of its clinical trials or if the Company terminates such agreements for convenience.

Contingencies—From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business. The Company recognizes any associated legal fees as incurred and accrues a liability for such contingent liability matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. For all periods presented, the Company was not a party to any pending material litigation or other material legal proceedings, except that on October 12, 2023, Rocket Pharmaceuticals, Inc. (“Rocket”) filed a lawsuit in the U.S. District Court for the Southern District of New York against the Company and two former employees that claimed, among other things, misappropriation of confidential information and trade secrets. The complaint alleged the individual defendants downloaded confidential Rocket company documents and other proprietary materials prior to leaving Rocket in 2021 and that the Company used this information to advance its programs after they became employed at the Company. The complaint sought unspecified damages and asked the court to enjoin the Company from competing and working in the market for gene therapy treatments targeting cardiac diseases. In August 2024, the Company asserted counterclaims against Rocket and Spacecraft Seven LLC, a wholly owned subsidiary of Rocket, for misappropriation of trade secrets, correction of inventorship of certain patents, breach of contract, and tortious interference with contract. The Company's counterclaims sought equitable relief, damages, attorneys' fees and costs from Rocket and Spacecraft Seven LLC. In June 2025, the litigation was resolved amicably and without admission of liability by any party, and all claims have been dismissed with prejudice.

Indemnification Agreements—In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its Board of Directors and executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. For all periods presented, the Company has not incurred any material costs as a result of such indemnifications.

12. License, Acquisition, Research and Collaboration and Sponsored Research Agreements

Adverum Biotechnologies—On January 25, 2021, the Company entered into an exclusive license agreement with Adverum Biotechnologies Inc. (“Adverum”) to in-license materials and technology related to the treatment of cardiomyopathy due to Friedreich's ataxia ("FA") (as amended in February 2022, the “Adverum Agreement”). In connection with the Adverum Agreement, the Company gained access to a portfolio of inventions, patent rights, technology, and licensed methods that the Company continues to develop, and the Company will assume all development and commercialization activities worldwide. Pursuant to the Adverum Agreement, the Company paid a one-time up-front non-refundable fee of $7.5 million, and is obligated to pay aggregate development and regulatory milestones of up to $17.5 million including a $3.5 million development milestone that was achieved and paid in the first quarter of 2023, and aggregate sales event and commercialization milestones of up to $49.0 million. The Company is obligated to pay Adverum tiered royalties ranging from high single-digits to sub teens based on annual aggregate worldwide net sales of Products (as defined in the Adverum Agreement). As of September 30, 2025, there were no research and development expenses recorded by the Company or payments made to Adverum under the terms of the Adverum Agreement other than the one-time up-front non-refundable fee of $7.5 million and the $3.5 million development milestone that was achieved and paid in the first quarter of 2023.

The Adverum Agreement remains in effect until termination at the date of the last royalty term to expire. The Company can terminate the Adverum Agreement with

120

days’ written notice. The Adverum Agreement can also be terminated as a result of a patent challenge, material breach of contractual terms, or insolvency by either party. Cornell University—On May 28, 2020, the Company entered into two exclusive license agreements with Cornell University (“Cornell”) (each, as amended, the “First Cornell License Agreement” and the “Second Cornell License Agreement,” respectively; collectively the “May 2020 Cornell License Agreements”). The First Cornell License Agreement is for the in-license of technology related to portfolios for APOE-associated Alzheimer’s disease and Anti-Tau, although the Company’s license is not restricted by such indications and it includes assignment to the Company of Cornell’s IND for the use of AAVrh10.hAPOE2 vector to treat APOE4 homozygous patients who are at risk for or have Alzheimer’s disease to support development of the Company’s LX1001 program. The Second Cornell License Agreement is for the in-license of technology related to a portfolio for FA although the Company’s license is not restricted by such indications, and it includes assignment to the Company of Cornell’s IND for the use of AAVrh.10cUhCLN2 to treat children with CLN2 Batten disease to support development of the Company’s LX1004 program. Through the May 2020 Cornell License Agreements, the Company gains access to a portfolio of inventions, patent rights, technology, and licensed methods that the Company continues to develop. Under the terms of the May 2020 Cornell License Agreements, the Company has assumed all development and commercialization activities worldwide with respect to the licensed technology.

As initial consideration for the May 2020 Cornell License Agreements, the Company paid Cornell an upfront payment in cash of $0.3 million and issued $1.3 million of notes (the “Cornell Notes”). In November 2020, the Cornell Notes with outstanding principal of $1.3 million were cancelled in exchange for 1,337,610 shares of series A convertible preferred stock, which converted into 126,258 shares of common stock upon the closing of the Company's IPO on November 7, 2023. As additional consideration, the Company is required to pay Cornell up to $8.4 million upon the achievement of specific clinical and regulatory milestones under the First Cornell License Agreement and up to $4.3 million in two portfolios and up to $0.6 million for a third portfolio upon the achievement of specific clinical and regulatory milestones under the Second Cornell License Agreement. In the second quarter of 2022, a clinical and regulatory milestone of $0.1 million was recognized and paid to Cornell in connection with the Second Cornell License Agreement. The Company is also required to pay Cornell a flat royalty in the mid-single-digits based on net sales of the products covered by the licenses, subject to certain adjustments.

Upon expiration of the royalty term of a given licensed product in a country, the respective license becomes non-exclusive and royalty-free. In addition, each of the May 2020 Cornell License Agreements may be terminated by the Company for any reason upon ninety (90) days’ advance notice to Cornell and by Cornell upon the Company’s material uncured breach, and all licenses and rights granted by either party under such agreement will concurrently terminate.

On April 21, 2024, the Company entered into the Third License Agreement (as amended, the “Third Cornell License Agreement,” together with the May 2020 Cornell License Agreements, the “Cornell License Agreements”) with Cornell. Pursuant to the Third Cornell License Agreement, Cornell has granted the Company an exclusive license to practice under certain patent rights generated in animal studies conducted by Cornell on behalf of the Company and a non-exclusive license to know-how concerning a gene therapy for FA cardiomyopathy and current and future data generated in an ongoing investigator-initiated Phase 1A trial of AAVrh.10hFXN to treat FA cardiomyopathy. Both licenses are worldwide and cover products with human and non-human prophylactic and therapeutic uses. Cornell has also granted the Company a right of reference to Cornell’s Investigation New Drug application for a gene therapy for FA cardiomyopathy.

Under the Third Cornell License Agreement, the Company paid a license issue fee and an initial data transfer fee to Cornell totaling $0.6 million. Additionally, the Company will be paying an annual data transfer fee of $50,000 until data is no longer being gathered. The Company has agreed to pay annual license maintenance fees ranging from $2,500 to $25,000 until such time the Company commercializes a licensed product. In addition, the Company will pay Cornell up to an aggregate of $2.1 million in regulatory milestones and up to an aggregate of $100 million in commercial milestones, plus low single digit royalties on net sales.

The Third Cornell License Agreement contains other customary license terms including terms related to sublicensing, development, commercialization, milestones, royalties, intellectual property, and termination. Upon expiration of the applicable royalty term for a product in a given country, the Company shall retain a non-exclusive, royalty free license to the data and know-how, including to continue selling such product in that country.

Cornell may terminate the Third Cornell License Agreement if the Company (i) breaches the Third Cornell License Agreement (subject to a cure period), (ii) participates in any proceeding challenging the validity of the licensed patents, (iii) publishes the licensed data without Cornell’s prior written consent, or (iv) does not reach certain milestones. Cornell may also terminate the Third Cornell License Agreement in part on product-by-product basis if the Company does not diligently develop and sale a product. The Company may terminate the Third Cornell License Agreement, in whole or in part with respect to the right of reference, or the licensed data, know-how, or patent rights, with 90 days’ prior written notice to Cornell.

During the three months ended September 30, 2025 and September 30, 2024, the Company did not incur or pay any expenses in connection with the Cornell License Agreements. During the nine months ended September 30, 2025, the Company incurred and paid $0.1 million in connection with the Cornell License Agreements. During the nine months ended September 30, 2024, the Company incurred and paid $0.7 million in connection with the Cornell License Agreements.

Stelios Therapeutics, Inc.—Stelios Therapeutics, Inc. (“Stelios”) was an early-stage company developing novel adeno-associated AAV-based gene therapies for rare cardiac conditions including arrhythmogenic cardiomyopathy and TNNI3-associated hypertrophic cardiomyopathy. On July 16, 2021, the Company acquired 100% of the outstanding stock of Stelios that was accounted for as an asset acquisition pursuant to FASB ASC 805, Business Combinations. The Company is required to pay up to a remaining aggregate of $12.5 million to the selling shareholders of Stelios upon the achievement of certain development milestones, excluding a $6.0 million development milestone that was achieved in the third quarter of 2024 and paid in the fourth quarter of 2024. Dr. Eric Adler, the Company's Chief Medical Officer and Head of Research, was a co-founder of Stelios and a selling shareholder. Of the $6.0 million development milestone payment, Dr. Adler received approximately $1.3 million. Stelios was merged into the Company on December 15, 2022 and ceased to exist.

Regents of the University of California, San Diego—Stelios entered into exclusive worldwide license agreements on April 23, 2020, and August 6, 2020 (each, as amended, the “First UCSD Agreement” and the “Second UCSD Agreement,” respectively) with the Regents of UCSD to in-license materials and intellectual property related to gene therapies for arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy, respectively. The First UCSD Agreement and the Second UCSD Agreement relate to the Company’s development efforts for its LX2021 and LX2022 programs, respectively. In connection with the First UCSD Agreement and the Second UCSD Agreement, the Company gained access to inventions, patent rights, technology, and licensed methods that it continues to develop, and it has assumed all worldwide development and commercialization activities with respect to the licensed technologies. The First UCSD Agreement and Second UCSD Agreement required Stelios to pay one-time up-front non-refundable cash fees of $20,000 for each agreement and requires the Company to pay aggregate development and commercialization milestones of up to $4.8 million and $2.4 million, respectively, and low- to mid-single digit royalties and low-single digit royalties, respectively, based on aggregate net sales. The only research and development expenses incurred by Stelios or the Company and payments made to the Regents of UCSD through September 30, 2025 under the terms of the First UCSD Agreement and the Second UCSD Agreement were the one-time up-front non-refundable cash fees of $20,000 for each agreement. The Company has the right to terminate the First UCSD Agreement and the Second UCSD Agreement at any time upon sixty (60)-days’ written notice to the Regents of UCSD.

On October 4, 2021, the Company entered into an exclusive worldwide license agreement (as amended, the “Third UCSD Agreement” and collectively with the First UCSD Agreement and the Second UCSD Agreement, the “UCSD Agreements”) with the Regents of UCSD to in-license materials and intellectual property related to LX2020, a gene therapy for arrhythmogenic right ventricular cardiomyopathy. The Third UCSD Agreement relates to the Company’s development efforts for its LX2020 program. In connection with the Third UCSD Agreement, the Company gained access to inventions, patent rights, technology, and licensed methods that it continues to develop, and it has assumed all worldwide development and commercialization activities with respect to the licensed technology. The Third UCSD Agreement required the Company to pay a one-time up-front non-refundable cash fee of $20,000 and requires the Company to pay aggregate development and commercialization milestones of up to $4.0 million, and low- to mid-single digit royalties based on aggregate net sales. Research and development expenses incurred by the Company and payments made to the Regents of UCSD under the terms of the Third UCSD Agreement include the one-time up-front non-refundable cash fee of $20,000 as well as a $0.1 million development milestone that was achieved during the third quarter of 2024. The Company has the right to terminate the Third UCSD Agreement at any time upon sixty (60)-days’ written notice to the Regents of UCSD.

On December 3, 2021, the Company entered into two sponsored research agreements with the Regents of UCSD (the "First UCSD SRA", the "Second UCSD SRA", and collectively, the “Initial UCSD SRAs”) for the Company’s LX2020, LX2021 and LX2022 programs in connection with the UCSD Agreements. Under the terms of the Initial UCSD SRAs, the Company has the first rights to obtain non-exclusive or exclusive, sublicensable, royalty-bearing, perpetual and transferable worldwide licenses in any resulting inventions owned by the Regents of UCSD or resulting inventions jointly owned between the Company and the Regents of UCSD, and the Company retains the rights to any resulting inventions owned by the Company. The Initial UCSD SRAs each have a two-year term and may be terminated early by the Company at any time upon the giving of thirty (30) days’ written notice to the Regents of UCSD. The total costs to be invoiced to the Company over the terms of the Initial UCSD SRAs are $5.6 million.

On April 13, 2024, the Company entered into a third sponsored research agreement with the Regents of UCSD (the “Third UCSD SRA”) for the Company’s LX2022 program in connection with the Second UCSD Agreement. Under the terms of the Third UCSD SRA, the Company has the first rights to obtain non-exclusive or exclusive, sublicensable, royalty-bearing, perpetual and transferable worldwide licenses in any resulting inventions owned by the Regents of UCSD or resulting inventions jointly owned between the Company and the Regents of UCSD, and the Company retains the rights to any resulting inventions owned by the Company. The Third UCSD SRA has a two-year term and may be terminated early by the Company at any time upon the giving of thirty (30) days’ written notice to the Regents of UCSD. The costs to be invoiced to the Company over the term of the Third UCSD SRA are $0.7 million, and the Company may incur additional costs of $0.6 million under the Third UCSD SRA if certain study objectives are met.

On April 13, 2024, the Company also entered into an amendment to the Second UCSD SRA (as amended, the "Amended Second UCSD SRA") for the Company’s LX2022 program that extended the term of the Second UCSD SRA to December 2024.

On each of April 19, 2024 and September 27, 2024, the Company also entered into an amendment to the First UCSD SRA (as amended, the "Amended First UCSD SRA", and together with the Amended Second UCSD SRA and the Third UCSD SRA, the "UCSD SRAs") for the Company’s LX2021 program in connection with the First UCSD Agreement. The Amended First UCSD SRA extends the term of the First UCSD SRA to December 2026 and provides for additional research and development studies and expenses. The total costs to be invoiced to the Company under the Amended First UCSD SRA are $0.7 million.

During the three months ended September 30, 2025, the Company incurred and paid $0 to the Regents of UCSD in connection with the UCSD SRAs. During the nine months ended September 30, 2025, the Company incurred and paid $0.1 million to the Regents of UCSD in connection with the UCSD SRAs. During the three months ended September 30, 2024, the Company incurred and paid totals of $0.2 million and $0.6 million, respectively, to the Regents of UCSD in connection with the UCSD SRAs. During the nine months ended September 30, 2024, the Company incurred and paid totals of $1.0 million and $1.6 million, respectively, to the Regents of UCSD in connection with the UCSD SRAs. The Company has incurred and paid cumulative totals of $5.2 million and $4.9 million, respectively, to the Regents of UCSD as of September 30, 2025, in connection with the UCSD SRAs.

13. Segment Information

The Company's Chief Operating Decision Maker ("CODM") is its chief executive officer and senior leadership team. All of the Company’s operating results are reviewed by the Company’s CODM within the same statement of operations and comprehensive loss whether research and development, by program, or general and administrative in nature. Accordingly, the Company has determined that it has a single reportable segment and operating segment structure. The Company's CODM regularly reviews net loss, as well as total expenses and expenses by significant areas such as departments and programs, to make decisions when evaluating the Company's financial performance. The Company does not evaluate performance or allocate resources based on segment asset data and therefore such information is not presented. All long-lived assets are located in the United States.

The following table contains additional information on the Company's net loss, including significant segment expenses, for the three and nine months ended September 30, 2025 and September 30, 2024:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2025			2024			2025			2024
Research and development expense
LX2006	$	5,135		$	2,355		$	12,072		$	9,476
LX2020		3,137			11,367			12,058			20,054
LX1001		108			1,033			735			1,870
Other programs		737			1,086			1,457			3,015
Employee compensation expenses		4,810			5,924			16,533			16,684
Lab-related costs and supplies		449			422			1,128			1,054
All other research and development expense		1,319			1,236			3,604			3,572
General and administrative expense
Employee compensation expenses		3,083			3,782			10,875			9,470
All other general and administrative expense		2,870			4,338			27,679			13,190
Other income		(1,365	)		(2,054	)		(7,099	)		(5,975	)
Net loss	$	(20,283	)	$	(29,489	)	$	(79,042	)	$	(72,409	)

14. Subsequent Events

Subsequent events have been evaluated through the date that these unaudited condensed financial statements were issued and were available to be issued.

On October 16, 2025, the Company entered into an underwriting agreement to issue and sell an aggregate of 15,625,000 shares of its common stock at a price of $8.00 per share, less underwriting discounts and commissions, in a public offering that closed on October 20, 2025 (the "October 2025 Public Offering"). In addition, the Company granted the underwriters of the October 2025 Public Offering a 30-day option to purchase up to an additional 2,343,750 shares of the Company's common stock a price of $8.00 per share, less underwriting discounts and commissions (the "30-day Underwriter Option"), which was exercised in full. The gross and estimated net proceeds received from the October 2025 Public Offering including the full exercise of the 30-day Underwriter Option were approximately $143.8 million and $134.6 million, respectively, after deducting approximately $9.2 million of underwriter commissions and other estimated offering costs.

On October 16, 2025, the Company entered into a securities purchase agreement to sell and issue pre-funded warrants to purchase 1,250,015 shares of the Company's common stock at a purchase price of $7.9999 per pre-funded warrant, in a private placement that closed on October 20, 2025 (the "October 2025 Private Placement", and together with the October 2025 Public Offering and the 30-day Underwriter Option, the "October 2025 Financing Transactions"). The gross and estimated net proceeds received from the October 2025 Private Placement were approximately $10.0 million and $9.3 million, respectively, after deducting approximately $0.7 million of placement agent fees and other estimated offering costs. The pre-funded warrants issued in the October 2025 Private Placement do not expire and are immediately exercisable at an exercise price of $0.0001 per pre-funded warrant share, except that the pre-funded warrants cannot be exercised by the holder if, after giving effect thereto, the holder would beneficially own more than 9.99% of the Company’s common stock (the "October 2025 Private Placement Maximum Percentage"). The October 2025 Private Placement Maximum Percentage can be changed at the holder's election to any other percentage not in excess of 19.99%, and any increase in the October 2025 Private Placement Maximum Percentage will not be effective until the 61st day after the holder provides notice to the Company of the desired increase.

On November 4, 2025, the Company's board of directors adopted the 2025 Inducement Equity Plan and, subject to the adjustment provisions of the 2025 Inducement Equity Plan, reserved 2,000,000 shares of the Company's common stock for issuance pursuant to equity awards granted under the 2025 Inducement Equity Plan.

Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations.

You should read the following discussion and analysis of our financial condition and results of operations together with our unaudited condensed financial statements and the related notes appearing elsewhere in this Quarterly Report on Form 10-Q. As a result of many factors, including those factors set forth in the “Risk Factors” section of this Quarterly Report on Form 10-Q, our actual results could differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis. Please also see the section titled “Special Note Regarding Forward Looking Statements.” Unless the context requires otherwise, references in this Quarterly Report on Form 10-Q to “we,” “us” and “our” refer to Lexeo Therapeutics, Inc.

We are a clinical stage genetic medicine company dedicated to reshaping heart health by applying pioneering science to fundamentally change how cardiovascular diseases are treated. We are advancing a portfolio of therapeutic candidates that take aim at the underlying genetic causes of conditions, including FA cardiomyopathy, plakophilin-2, or PKP2, arrhythmogenic cardiomyopathy, or ACM, and other devastating diseases with high unmet need.

Recent developments

Our most advanced cardiovascular product candidate, LX2006 for the treatment of FA cardiomyopathy, is currently being evaluated in SUNRISE-FA, our ongoing Phase 1/2 clinical trial, and in a Cornell investigator-initiated trial. In October 2025, we announced progress in regulatory interactions with the FDA on LX2006. In response to questions from us regarding the possibility of a faster path to a Biologics License Application, or BLA, the FDA has indicated openness to a BLA submission for accelerated approval that includes clinical data from our ongoing Phase 1/2 studies of LX2006 pooled with new clinical data to be generated in the planned pivotal study. To enable pooling of these data to support licensure, we will submit enhanced manufacturing comparability data and meet an additional nonclinical requirement, given our intention to leverage our optimized, high-yield Sf9-baculovirus manufacturing platform for future clinical and commercial drug supply, compared to the adherent HEK293 process used for our Phase 1/2 clinical supply. In October 2025, we shared Chemistry, Manufacturing and Controls, or CMC, data for LX2006, which were submitted to the FDA to support analytical comparability between the HEK293 manufacturing process and the Sf9-baculovirus manufacturing platform. These data demonstrate similar frataxin expression in vitro between the two processes as measured by a quantitative relative potency assay in cardiomyocytes. In November 2025, the FDA approved this analytical comparability report establishing comparability between LX2006 HEK293 and Sf9 manufacturing processes, endorsing use of the optimized, Sf9 final commercial manufacturing process for LX2006 in the planned pivotal study and clearing compatibility requirements to begin dosing patients.

Along with the regulatory announcement, we provided an interim clinical update on LX2006, which included baseline characteristics and safety data from the 17 treated participants across the two studies, and clinical efficacy data from the 16 participants who had reached at least six months of follow up as of that time. These data showed sustained or deepening improvements in the majority of participants across both cardiac and neurologic measures of FA, exceeding the thresholds previously agreed with FDA for co-primary endpoints LVMI and frataxin expression. We shared that the FDA had previously agreed to evaluate the co-primary endpoint of LVMI at a time point earlier than 12 months. LX2006 has been generally well-tolerated across both trials to date, with no clinically significant complement activation. We continue to engage with the FDA on the planned pivotal study protocol and comparability. In discussions to date, there have been no changes to the previously disclosed alignment with the FDA on key parameters related to the LX2006 planned pivotal study.

Our second most advanced cardiovascular product candidate, LX2020 for the treatment of ACM caused by mutations in the PKP2 gene, referred to as PKP2-ACM, is currently being evaluated in HEROIC-PKP2, an ongoing Phase 1/2 clinical trial. We have completed enrollment and dosing in this trial, with ten participants dosed: three in the low dose cohort 1 (2×1013 vg/kg), three in the high dose cohort 2 (6×1013 vg/kg), and four in the dose-expansion high dose cohort 3 (6×1013 vg/kg). Across all participants dosed, LX2020 has been generally well-tolerated, with no clinically significant complement activation to date. In October 2025, we reported that one Grade 3 serious adverse event, which was assessed as possibly treatment related, of sustained ventricular tachycardia, or SVT, had been observed three months after dosing in a single participant in the high dose cohort of the HEROIC-PKP2 Phase 1/2 clinical trial. The participant was successfully treated with anti-arrhythmic medication and was discharged with no additional intervention required. This patient had a documented history of prior VTs and had an implantable cardioverter defibrillator in place.

For the three participants in low dose cohort 1 (n=2 at 12 months; n=1 at 9 months), multiple cardiac parameters were assessed at latest visit relative to baseline:

• Arrythmia burden: Premature ventricular contractions were reduced in one of three participants and non-sustained ventricular tachycardia was reduced or stable in two of three participants.

• Electrical activity: QRS duration was normalized or stable in two of three participants and T-wave inversions were reduced in two of three participants.

• Cardiac function: Left ventricular ejection fraction and right ventricular ejection fraction were stable in three of three participants.

We anticipate sharing additional safety and clinical efficacy data in January 2026 at the J.P. Morgan Healthcare Conference once most participants in the high dose cohorts reach at least six months of follow up. This data update is expected to include data from such high dose cohort patients and three low dose participants with at least 12 months of follow up, as well as five cardiac biopsies from the high dose cohorts analyzed at baseline and three months after dosing.

Each of our gene therapy candidates utilizes the vector construct, dose and route of administration that we believe will result in the most favorable biodistribution and safety profile for our product candidate for each disease. Our most advanced programs use the AAVrh10 vector due to its high transduction efficiency in myocardial cells, potential for lower toxicity given the opportunity to utilize lower doses compared to other well-established AAV serotypes, and low pre-existing immunity.

Public offering

On October 20, 2025, the Company completed the October 2025 Public Offering of 17,968,750 shares of its common stock at a price of $8.00 per share, for proceeds to the Company of $134.6 million, net of transaction costs, including the full exercise of the underwriters’ over-allotment option.

Private placement

On October 20, 2025, the Company completed the October 2025 Private Placement, in which the Company sold pre-funded warrants to purchase 1,250,015 shares of the Company's common stock at a purchase price of $7.9999 per pre-funded warrant. The proceeds to the Company were $9.3 million, net of transaction costs. The pre-funded warrants issued in the October 2025 Private Placement do not expire and are immediately exercisable at an exercise price of $0.0001 per pre-funded warrant share.

Current and future capital requirements

To date, we have funded our operations primarily through proceeds from the sale of shares of our convertible preferred stock, common stock, and pre-funded warrants and warrants to purchase our common stock, including from our October 2025 Financing Transactions, May 2025 Private Placement, March 2024 Private Placement, IPO and the subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares of common stock. As of September 30, 2025, we had $122.8 million of cash, cash equivalents, and investments in U.S. Treasury securities. We have incurred significant operating losses since the commencement of our operations. Our ability to generate product revenue sufficient to achieve profitability will depend heavily on the successful development and eventual commercialization of one or more of our current gene therapy candidates or any future gene therapy candidates. Our net losses for the nine months ended September 30, 2025 and the year ended December 31, 2024 were $79.0 million and $98.3 million, respectively, and our accumulated deficit was $359.2 million at September 30, 2025. We expect to continue to incur significant losses for the foreseeable future as we advance our current and future product candidates through preclinical and clinical development, continue to build our operations and operate as a public company.

We expect to continue to incur net operating losses for at least the next several years, and we expect our research and development expenses, general and administrative expenses, and capital expenditures to continue to increase. We expect our expenses and capital requirements will increase significantly in connection with our ongoing activities as we:

• continue our ongoing and planned clinical trials as well as research and development of our FA cardiomyopathy (LX2006) and arrhythmogenic cardiomyopathy caused by mutations in the PKP2 gene, or PKP2-ACM (LX2020) programs and other product candidates;

• initiate preclinical studies and clinical trials for any additional product candidates that we may pursue in the future;

• seek to discover and develop additional product candidates and further expand our clinical product pipeline;

• seek regulatory approvals for any product candidates that successfully complete clinical trials;

• invest in capital equipment in order to expand our research and development and manufacturing activities;

• attract, hire and retain additional clinical, scientific, quality control, regulatory, and manufacturing management and administrative personnel;

• add clinical, operational, financial and management information systems and personnel, including personnel to support our product development;

• develop, maintain, expand, protect and enforce our intellectual property portfolio, including patents, trade secrets and know-how;

• acquire or in-license other product candidates and technologies;

• expand our operations in the United States and to other geographies;

• incur additional legal, accounting, investor relations and other general and administrative expenses associated with operating as a public company; and

• establish a sales, marketing and distribution infrastructure, either ourselves or in partnership with others, to commercialize any product candidates, if approved, and related additional commercial manufacturing costs.

Components of our results of operations

Revenue

To date, we have not generated any revenue from product sales. If our development efforts for LX2006 and LX2020, or any future product candidates, are successful and result in regulatory approval, or if we enter into collaboration or license agreements with third parties, we may generate revenue in the future from product sales, royalties or payments from such collaboration or license agreements, or a combination of product sales and payments from such agreements.

Operating expenses

Research and development

Research and development expenses consist of costs incurred for our research activities, including our discovery efforts and the preclinical and clinical development of our programs. These expenses include:

• employee-related expenses, including salaries, benefits, and stock-based compensation expense for employees engaged in research and development functions;
• expenses incurred under agreements with third parties, such as consultants, clinical investigators, contractors and CROs that assist with (i) identification of potential product candidates in discovery platforms and (ii) the preclinical and clinical studies of our product candidates;
• the cost of developing and scaling our manufacturing process and manufacturing product candidates for use in our research, preclinical studies and clinical trials, including under agreements with third parties, such as consultants, contractors and contract manufacturing organizations, or CMOs;
• costs to maintain compliance with FDA and other regulatory requirements;
• laboratory supplies and research materials;
• facilities, depreciation, and other expenses, which include direct and allocated expenses for rent and maintenance of facilities;
• payments made under our licensing agreements with third parties, including milestone payments; and
• other expenses incurred as a result of research and development activities.

We expense research and development costs as expenses when incurred. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. When third-party service providers’ billing terms do not coincide with our period-end, we are required to make estimates of our obligations to those third parties incurred in a given accounting period and record accruals at the end of the period. We base these estimates on our knowledge of the research and development programs, services performed for the period, past history for related activities and the expected duration of the third-party service contract, where applicable. If timelines or contracts are modified based upon changes in the scope of work to be performed, we modify our estimates of accrued expenses accordingly on a prospective basis; therefore, actual results could differ from our estimates. Upfront payments under license agreements are expensed upon receipt of the license, and annual maintenance fees under license agreements are expensed in the period in which they are incurred. Milestone payments under license agreements are accrued, with a corresponding expense being recognized, in the period in which the milestone is determined to be probable of achievement and the related amount is reasonably estimable.

Our direct research and development expenses are tracked on a program-by-program basis and consist primarily of external costs, such as fees paid to CROs, CMOs, central laboratories and certain outside consultants in connection with our research and discovery, preclinical development, process development, manufacturing, clinical development, clinical trials, regulatory and quality assurance activities. We do not allocate professional services costs and licensing fees and other similar costs to specific programs because these costs are deployed across multiple programs.

Research and development activities are central to our business model and account for a significant portion of our operating expenses. Product candidates in later stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of later-stage clinical trials. As a result, we expect our research and development expenses to increase for the foreseeable future as we further advance LX2006 and LX2020, and any other future product candidates that we may develop, into and through preclinical studies and clinical trials and pursue regulatory approvals. We cannot determine with certainty the timing of initiation, the duration or the completion costs of current or future preclinical studies and clinical trials of our product candidates due to the inherently unpredictable nature of preclinical and clinical development. Clinical and preclinical development timelines, the probability of success and development costs can differ materially from expectations. We anticipate that we will make determinations as to which product candidates to pursue and how much funding to direct to each product candidate on an ongoing basis in response to the results of ongoing and future research, preclinical studies and clinical trials, regulatory developments and our assessments as to each product candidate’s commercial potential. In addition, we cannot forecast whether any of our current or future product candidates will be subject to future collaborations, when such arrangements will be secured, if at all, and to what degree such arrangements would affect our development plans and capital requirements. We are also unable to predict when, if ever, we will generate revenue from our product candidates to offset our expenses.

General and administrative

General and administrative expenses consist primarily of personnel expenses, including salaries, benefits and stock-based compensation expense for personnel in executive, accounting, business development, legal, human resources and administrative functions. General and administrative expenses also include corporate facility costs not otherwise included in research and development expenses, depreciation, and other expenses, which include direct or allocated expenses for rent and maintenance of facilities and insurance, not otherwise included in research and development expenses, as well as professional fees for legal, consulting, investor and public relations, accounting and audit services.

We expect that in the near to medium term future our general and administrative expenses will (i) at least approximate those incurred during the three months ended September 30, 2025 on a quarterly basis, and (ii) decrease relative to those incurred during the nine months ended September 30, 2025 on an annualized basis, primarily due to lower anticipated third-party legal fees and related costs, while supporting the continued research and development of our programs and the growth of our business.

Gain on long-term investment

Gain on long-term investment includes non-operating income related to an unrealized gain on convertible preferred stock received that was recorded at fair value to long-term investment.

Other income (expense), net

Other income (expense), net includes foreign exchange gains and (losses).

Interest expense

Interest expense is primarily associated with our finance right of use asset equipment leases.

Interest income

Interest income is primarily related to interest earned from our investments in U.S. government money market funds and interest earned from our investments in U.S. Treasury securities, as well as interest earned on interest-bearing demand deposit cash accounts and a cash collateral account.

Amortization of premium on investments

Amortization of premium on investments consists of amortization of premium on our investments in U.S. Treasury securities.

Income taxes

Provision for income taxes consists of U.S. federal and state income taxes in the jurisdictions where we conduct business. Since our inception, we have not recorded any income tax benefits for the net losses we have incurred in each year or for our research and development tax credits, as we believe, based upon the weight of available evidence, that it is more likely than not that all of our net operating loss, or NOL, carryforwards and tax credits will not be realized. Accordingly, we have recorded a full valuation allowance against our net deferred tax assets at September 30, 2025, December 31, 2024 and September 30, 2024. As of September 30, 2025, December 31, 2024 and September 30, 2024, we had no unrecognized tax benefits.

Results of operations

Comparison of the three months ended September 30, 2025 and 2024

The following table summarizes our results of operations for the three months ended September 30, 2025 and 2024 (in thousands):

	Three Months Ended September 30,
	2025			2024			Change
Operating expenses
Research and development	$	15,695		$	23,423		$	(7,728	)
General and administrative		5,953			8,120			(2,167	)
Total operating expenses		21,648			31,543			(9,895	)
Operating loss		(21,648	)		(31,543	)		9,895
Other income and expense
Other income (expense), net		(9	)		(3	)		(6	)
Interest expense		(22	)		(35	)		13
Interest income		1,456			2,092			(636	)
Amortization of premium on investments in U.S. Treasury securities		(60	)		-			(60	)
Total other income and expense		1,365			2,054			(689	)
Loss from operations before income taxes		(20,283	)		(29,489	)		9,206
Income taxes		-			-			-
Net Loss	$	(20,283	)	$	(29,489	)	$	9,206

Research and development expenses

The following table summarizes our research and development expenses incurred for the three months ended September 30, 2025 and 2024 (in thousands):

	Three Months Ended September 30,
	2025		2024		Change
Direct external research and development expenses by program:
LX2006	$	5,135	$	2,355	$	2,780
LX2020		3,137		11,367		(8,230	)
LX1001		108		1,033		(925	)
Other programs		737		1,086		(349	)
Total direct external research and development expenses by program		9,117		15,841		(6,724	)
Unallocated research and development expenses:
Employee and stock-based compensation expenses		4,810		5,924		(1,114	)
Lab-related costs and supplies		449		422		27
Professional fees		423		434		(11	)
Other unallocated costs, including facilities		896		802		94
Total unallocated research and development expenses:		6,578		7,582		(1,004	)
Total research and development expenses	$	15,695	$	23,423	$	(7,728	)

The net decrease of $7.7 million in total research and development expenses for the three months ended September 30, 2025 compared to the three months ended September 30, 2024 was primarily due to decreases in (i) milestone expenses of $6.1 million, consisting primarily of a $6.0 million development milestone for our LX2020 program that was achieved during the third quarter of 2024 and subsequently paid to the selling shareholders of Stelios, (ii) employee compensation and stock-based compensation expenses of $1.1 million due to decreased headcount associated with a limited reduction-in-force undertaken in April 2025, and (iii) CMC expenses of $0.9 million. These decreases were partially offset by an increase in clinical trial expenses of $0.5 million.

General and administrative expenses

The net decrease of $2.2 million in general and administrative expenses for the three months ended September 30, 2025 compared to the three months ended September 30, 2024 was primarily due to a decrease in third-party legal fees and associated costs of $1.6 million, as well as a decrease in stock-based compensation expense of $0.8 million. These decreases were partially offset by increases in capital and franchise tax expenses of $0.2 million.

Interest income

We recognized interest income of $1.5 million and $2.1 million for the three months ended September 30, 2025 and September 30, 2024, respectively, primarily related to interest earned on our investments in U.S. government money market funds and our investments in U.S Treasury securities, with the decrease primarily due lower average invested balances, as well as lower interest rates.

Comparison of the nine months ended September 30, 2025 and 2024

The following table summarizes our results of operations for the nine months ended September 30, 2025 and 2024 (in thousands):

	Nine Months Ended September 30,
	2025			2024			Change
Operating expenses
Research and development	$	47,587		$	55,725		$	(8,138	)
General and administrative		38,554			22,659			15,895
Total operating expenses		86,141			78,384			7,757
Operating loss		(86,141	)		(78,384	)		(7,757	)
Other income and expense
Gain on long-term investment		3,390			-			3,390
Other income (expense), net		(27	)		(9	)		(18	)
Interest expense		(75	)		(107	)		32
Interest income		3,917			6,091			(2,174	)
Amortization of premium on investments in U.S. Treasury securities		(106	)		-			(106	)
Total other income and expense		7,099			5,975			1,124
Loss from operations before income taxes		(79,042	)		(72,409	)		(6,633	)
Income taxes		-			-			-
Net Loss	$	(79,042	)	$	(72,409	)	$	(6,633	)

Research and development expenses

The following table summarizes our research and development expenses incurred for the nine months ended September 30, 2025 and 2024 (in thousands):

	Nine Months Ended September 30,
	2025		2024		Change
Direct external research and development expenses by program:
LX2006	$	12,072	$	9,476	$	2,596
LX2020		12,058		20,054		(7,996	)
LX1001		735		1,870		(1,135	)
Other programs		1,457		3,015		(1,558	)
Total direct external research and development expenses by program		26,322		34,415		(8,093	)
Unallocated research and development expenses:
Employee and stock-based compensation expenses		16,533		16,684		(151	)
Lab-related costs and supplies		1,128		1,054		74
Professional fees		1,291		1,445		(154	)
Other unallocated costs, including facilities		2,313		2,127		186
Total unallocated research and development expenses:		21,265		21,310		(45	)
Total research and development expenses	$	47,587	$	55,725	$	(8,138	)

The net decrease of $8.1 million in total research and development expenses for the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 was primarily due to decreases in (i) milestone expenses of $6.1 million, consisting primarily of a $6.0 million development milestone for our LX2020 program that was achieved during the third quarter of 2024 and subsequently paid to the selling shareholders of Stelios, (ii) CMC expenses of $2.4 million, (iii) non-clinical, quality, and regulatory expenses of $0.8 million, (iv) license fees of $0.6 million related to the Third Cornell License Agreement that were incurred in 2024, and (v) clinical trial costs of $0.4 million excluding an adjustment reducing estimated accrued clinical trial expenses by $2.2 million for our LX1001 program recorded in the second quarter of 2024. These decreases were partially offset by an adjustment reducing estimated accrued clinical trial expenses by $2.2 million for our LX1001 program recorded in the second quarter of 2024.

General and administrative expenses

The net increase of $15.9 million in general and administrative expenses for the nine months ended September 30, 2025 compared to the nine months ended September 30, 2024 was primarily due to an increase in third-party legal fees and associated costs of $14.6 million, as well as an increase in employee compensation costs of $1.4 million primarily due to increased headcount.

Gain on long-term investment

We recorded non-operating income of approximately $3.4 million during the nine months ended September 30, 2025 related to an unrealized gain on convertible preferred stock received that was recorded at fair value to long-term investment.

Interest income

We recognized interest income of $3.9 million and $6.1 million for the nine months ended September 30, 2025 and September 30, 2024, respectively, primarily related to interest earned on our investments in U.S. government money market funds and our investments in U.S Treasury securities, with the decrease primarily due to lower average invested balances, as well as lower interest rates.

Liquidity and capital resources

Sources of liquidity

Since our inception, we have not generated any revenue from product sales and have incurred significant operating losses and negative cash flows from our operations. We expect to incur significant expenses and operating losses for the foreseeable future as we advance the clinical development of our product candidates. Since our inception through September 30, 2025, we funded our operations primarily through proceeds from the sale of shares of our convertible preferred stock, common stock, and pre-funded warrants and warrants to purchase our common stock, including from our October 2025 Financing Transactions, May 2025 Private Placement, March 2024 Private Placement, IPO and the subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares of common stock, with estimated net proceeds since our inception totaling $594.9 million. As of September 30, 2025 and December 31, 2024, we had cash, cash equivalents, and investments in U.S. Treasury Securities of $122.8 million and $128.5 million, respectively.

On March 24, 2025 we filed a prospectus supplement to the prospectus which forms a part of our effective shelf registration statement on Form S-3, dated December 13, 2024, which registers the offering, issuance, and sale of up to $75.0 million of common stock pursuant to our ATM Program. As of September 30, 2025, we have not sold any shares of common stock pursuant to the ATM Program. In October 2025, we raised $153.8 million in equity capital from the October Financing Transactions, receiving net proceeds of $143.9 million after transaction costs.

We believe that our cash, cash equivalents, and investments in U.S. Treasury securities balances will be sufficient to fund our planned operating expenses and capital expenditure requirements into 2028. Our total future capital requirements will depend on many factors and are subject to the risks and uncertainties set forth in “Item 1A Risk Factors.”

Cash flows

The following table summarizes our sources and uses of cash for the nine months ended September 30, 2025 and September 30, 2024 (in thousands):

	Nine Months Ended September 30,
	2025			2024
Net cash used in operating activities	$	(78,482	)	$	(52,825	)
Net cash provided by (used in) investing activities		11,437			(494	)
Net cash provided by financing activities		73,023			88,873
Net increase in cash	$	5,978		$	35,554

Operating activities

During the nine months ended September 30, 2025, net cash used in operating activities consisted primarily of our net loss of $79.0 million, which included an unrealized gain of $3.4 million recorded to other non-operating income upon receipt of our long-term investment in convertible preferred stock, in addition to $7.1 million of net cash used in changes in operating assets and liabilities, which were partially offset by $9.4 million of stock-based compensation expense and $1.3 million of depreciation expense and amortization of operating and finance right-of-use assets.

During the nine months ended September 30, 2024, net cash used in operating activities consisted primarily of our net loss of $72.4 million, which was partially offset by $9.1 million of net cash provided by changes in operating assets and liabilities, $9.0 million of stock-based compensation expense, and $1.5 million of depreciation expense and amortization of operating and finance right-of-use assets.

Investing activities

During the nine months ended September 30, 2025, net cash provided by investing activities was $11.4 million and consisted primarily of proceeds received upon maturities of investments in U.S. Treasury securities of $67.2 million, which was partially offset by purchases of investments in U.S. Treasury securities of $55.4 million and purchases of lab equipment of $0.4 million.

During the nine months ended September 30, 2024, net cash used in investing activities was $0.5 million and consisted primarily of purchases of lab equipment.

Financing activities

During the nine months ended September 30, 2025, net cash provided by financing activities consisted primarily of the net proceeds received from the May 2025 Private Placement offering of $73.1 million, as well as proceeds received from common stock issuances under the 2023 ESPP of $0.3 million, which were partially offset by $0.4 million of principal payments made on equipment finance leases.

During the nine months ended September 30, 2024, net cash provided by financing activities consisted primarily of the net proceeds received from the Private Placement offering of $88.7 million, as well as $0.5 million of proceeds received from the exercise of stock options, which were partially offset by $0.3 million of principal payments made on equipment finance leases.

Funding requirements

We expect our expenses and capital requirements to increase significantly in connection with our ongoing activities, particularly as we advance our lead product candidates and other development programs. Accordingly, we will continue to require substantial additional funding to support our continuing operations.

The timing and amount of our future operating and capital requirements will largely depend on many factors, including:

• the initiation, scope, progress, timing, results and costs of product discovery, preclinical studies and clinical trials for our product candidates or any future candidates we may develop;
• our ability to maintain our relationships with Cornell University, Adverum, The Regents of UCSD, and any other key licensors or collaborators;
• the scope, prioritization and number of our research and development programs;
• the costs, timing and outcome of seeking and obtaining regulatory approvals from the FDA and comparable foreign regulatory authorities, including the potential for such authorities to require that we perform more preclinical studies or clinical trials than those that we currently expect or change their requirements on studies that had previously been agreed to;
• our ability to establish and maintain collaborations on favorable terms, if at all;
• the achievement of milestones or occurrence of other developments that trigger payments under any collaboration agreements we have or may enter into;
• the extent to which we are obligated to reimburse, or entitled to reimbursement of, clinical trial costs under collaboration agreements, if any;
• the costs to establish, maintain, expand, enforce and defend the scope of our intellectual property portfolio, including preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending intellectual property-related claims;
• the extent to which we acquire or in-license other product candidates and technologies;
• the costs of securing manufacturing arrangements for commercial production;
• the costs of establishing or contracting for sales and marketing capabilities if we obtain regulatory approvals to market our product candidates; and
• our need to implement additional internal systems and infrastructure.

We may be unable to raise additional funds or enter into potential collaborations, strategic partnerships or marketing, distribution, licensing or other similar agreements or arrangements on favorable terms, or at all. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your stockholder ownership interest will be diluted. If we fail to raise capital or enter into such agreements or arrangements as, and when, needed, we may have to significantly delay, scale back or discontinue the development or commercialization of our product candidates or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Critical accounting policies and significant judgments and estimates

Our management’s discussion and analysis of our financial condition and results of operations are based on our financial statements, which have been prepared in accordance with U.S. generally accepted accounting principles, or U.S. GAAP. The preparation of our financial statements and related disclosures requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, expenses, and the disclosure of our contingent liabilities in our financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions or conditions.

Other than as disclosed in Note 2 to the condensed financial statements included in this Quarterly Report on Form 10-Q, there have been no significant changes to our critical accounting estimates from those described in our audited financial statements as of and for the year ended December 31, 2024 included in our Annual Report on Form 10-K, filed with the SEC on March 24, 2025.

JOBS Act accounting election

We qualify as an “emerging growth company” pursuant to the provisions of the JOBS Act. As an emerging growth company, we have elected to take advantage of the extended transition period to comply with new or revised accounting standards and to adopt certain of the reduced disclosure requirements available to emerging growth companies. As a result of the accounting standards election, we will not be subject to the same implementation timing for new or revised accounting standards as other public companies that are not emerging growth companies.

Item 3. Quantitative and qualitative disclosures about market risk.

We are a smaller reporting company, as defined by Rule 12b-2 under the Exchange Act and are not required to provide the information under this item.

Item 4. Controls and Procedures.

Evaluation of Disclosure Controls and Procedures

As required by Rule 13a-15(d) of the Exchange Act, our management, including our principal executive officer and our principal financial officer, conducted an evaluation of our internal control over financial reporting to determine whether any change occurred during the period covered by this Quarterly Report on Form 10-Q that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting. Based on the evaluation of our disclosure controls and procedures at September 30, 2025, our principal executive officer and our principal financial officer concluded that, as of such date, our disclosure controls and procedures were effective at the reasonable assurance level.

Changes in Internal Control Over Financial Reporting

There were no changes in our internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) during the fiscal quarter ended September 30, 2025 that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

• our preclinical studies and clinical trials may fail to demonstrate the safety and efficacy of our product candidates, or serious adverse or unacceptable side effects may be identified during the development of our product candidates, which could prevent or delay regulatory approval and commercialization, increase our costs or necessitate the abandonment or limitation of the development of some of our product candidates. We may also identify safety and efficacy concerns after the approval of a product candidate which can result in negative consequences to our business and results of operations;
• some of the diseases we initially seek to treat have low prevalence and it may be difficult to identify and enroll patients with these diseases. If we experience delays or difficulties in the enrollment and/or maintenance of patients in clinical trials, our receipt of necessary regulatory approvals could be delayed or prevented;
• we may seek Orphan Drug designation or Rare Pediatric Disease designation for some of our product candidates and we may be unsuccessful, or may be unable to maintain the benefits associated with Orphan Drug designation, including the potential for market exclusivity, for product candidates for which we obtain Orphan Drug designation;
• Fast Track, Breakthrough Therapy, or Regenerative Medicine Advanced Therapy designation that we may receive from the FDA may not actually lead to a faster development or regulatory review or approval process, and does not assure FDA approval of our product candidates;
• we have received Rare Pediatric Disease designation from the FDA for LX2006 for the treatment of FA and we may seek such designation for future product candidates if Congress extends the rare pediatric disease priority review program. However, a marketing application for these product candidates, if approved, may not meet the eligibility criteria for a rare pediatric disease priority review voucher;
• we and our contract manufacturers are subject to significant regulation with respect to manufacturing our products. The third-party manufacturing facilities on which we rely, and any manufacturing facility that we may have in the future, may have limited capacity or fail to meet the applicable stringent regulatory requirements;
• gene therapies are novel, complex and difficult to manufacture. We could experience manufacturing problems that result in delays in the development or commercialization of our product candidates or otherwise harm our business;
• we depend on third-party suppliers for materials used in the manufacture of our product candidates, and the loss of these third-party suppliers or their inability to supply us with adequate materials could harm our business;
• even if any of our product candidates receive marketing approval, they may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success;
• we rely on our collaborations with several leading academic institutions to conduct research and development for many of our pipeline programs, including conducting preclinical and IND-enabling studies for portions of our near-term future pipeline. Failure or delay of our academic partners to fulfill all or part of their respective obligations to us under our agreements, a breakdown in collaboration between the parties or a complete or partial loss of either of these relationships could materially harm our business;
• we intend to continue to rely on third parties to conduct a significant portion of our existing clinical trials and potential future clinical trials for product candidates, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials;
• if we are unable to obtain or protect intellectual property rights related to any of our product candidates, we may not be able to compete effectively in our market;
• changes in the FDA and other government agencies, regulatory actions and other actions under the current administration could hinder their ability to hire and retain key leadership and other personnel, or otherwise prevent new products and services from being developed or commercialized in a timely manner, which could negatively impact our business; and
• we may become subject to claims that we and our employees, consultants or independent contractors have wrongfully used or disclosed confidential information or trade secrets of third parties.

Risks related to our financial position and capital needs

We have incurred significant losses since our inception. We expect to incur losses over the next several years and may never achieve or maintain profitability.

Since our inception, we have incurred significant net losses, and we expect to continue to incur significant expenses and operating losses for the foreseeable future. For the nine months ended September 30, 2025 and the fiscal year ended December 31, 2024, we incurred net losses of $79.0 million and $98.3 million, respectively, and we had an accumulated deficit of $359.2 million as of September 30, 2025. We have primarily financed our operations with net proceeds from the October 2025 Financing Transactions, May 2025 Private Placement, the March 2024 Private Placement, net proceeds raised in our IPO and the subsequent partial exercise of the underwriters’ 30-day option to purchase additional shares of common stock, as well as sales of our convertible equity securities and the August 2023 convertible Simple Agreement for Future Equity note. We have no products approved for commercialization and have never generated any revenue from product sales.

We are still in the early clinical stages of development of our lead product candidates. We expect to continue to incur significant expenses and operating losses over the next several years. Our operating expenses and net losses may fluctuate significantly from quarter to quarter and year to year. We anticipate that our expenses will increase substantially as we:

• continue to advance the preclinical and clinical development of our product candidates and discovery programs;
• initiate and complete additional clinical trials of our current and future product candidates;
• seek regulatory approval for any product candidates that successfully complete clinical trials;
• continue to develop our gene therapy product candidate pipeline;
• scale up our clinical and regulatory capabilities;
• work with our third party manufacturing partners to produce material in accordance with cGMP for clinical trials or potential commercial sales;
• establish, either alone or with a third party, a commercialization infrastructure and scale up manufacturing and distribution capabilities to commercialize any product candidates for which we may obtain regulatory approval;
• adapt our regulatory compliance efforts to incorporate requirements applicable to marketed products;
• maintain, expand and protect our intellectual property portfolio and patent claims;
• hire additional clinical, quality control, regulatory, manufacturing, scientific and administrative personnel;
• add operational, financial and management information systems and personnel, including personnel to support our product development and planned future commercialization efforts; and
• incur additional legal, accounting and other expenses while operating as a public company.

To date, we have not generated any revenue from the commercialization of our product candidates. To become and remain profitable, we must succeed in developing and eventually commercializing product candidates that generate significant revenue. This will require us to be successful in a range of challenging activities, including completing preclinical testing and clinical trials of our product candidates, obtaining regulatory approval, and manufacturing, marketing and selling any product candidates for which we may obtain regulatory approval, as well as discovering and developing additional product candidates. We are only in the preliminary stages of most of these activities and all of our product candidates are in early clinical trials or preclinical development. We may never succeed in these activities and, even if we do, may never generate any revenue or revenue that is significant enough to achieve profitability.

Even if we achieve profitability, we may not be able to sustain or increase profitability on a quarterly or annual basis. Our failure to become and remain profitable would depress the value of our company and could impair our ability to raise capital, expand our business, maintain our development efforts, obtain product approvals, diversify our offerings or continue our operations. A decline in the value of our company could also cause you to lose all or part of your investment.

We have a limited operating history and no history of commercializing products, which may make it difficult for an investor to evaluate the success of our business to date and to assess our future viability.

We are a clinical stage genetic medicine company with a limited operating history. We commenced substantive business operations in 2020, and our operations to date have been largely focused on organizing and staffing our company, business planning, raising capital, entering into collaboration and license agreements for conducting preclinical and clinical research and development activities for our product candidates and gene therapy pipeline, and conducting clinical trials for our product candidates through CROs and other third parties. To date, we have not yet demonstrated our ability to successfully complete pivotal clinical trials, manufacture a product on a commercial scale or arrange for a third party to do so on our behalf, or conduct sales and marketing activities necessary for successful commercialization. Consequently, any predictions you make about our future success or viability may not be as accurate as they could be if we had a longer operating history or a history of successfully developing and commercializing products.

We will need substantial additional funding to meet our financial obligations and to pursue our business objectives. If we are unable to raise capital when needed, we could be forced to curtail our planned operations and the pursuit of our growth strategy.

We will require substantial future capital in order to complete planned and future clinical development for our lead product candidates, preclinical development for our other product candidates, and potential commercialization of these product candidates, if any are approved. We expect our spending levels to significantly increase in connection with our planned clinical trials of our lead product candidates. In addition, if we obtain marketing approval for any of our product candidates, we expect to incur significant expenses related to product sales, medical affairs, marketing, manufacturing and distribution. We also expect to incur additional costs associated with operating as a public company. Accordingly, we will need to obtain substantial additional funding in connection with our continuing operations. If we are unable to raise capital when needed or on acceptable terms, we would be forced to delay, reduce or eliminate certain of our clinical trials, our research and development programs or other operations.

As of September 30, 2025, we had cash, cash equivalents, and investments in U.S. Treasury securities of $122.8 million. We believe that our cash, cash equivalents and investments in U.S. Treasury securities balances will be sufficient to fund our operating expenses and capital requirements into 2028. This estimate is based on assumptions that may prove to be wrong, and we could use our available capital resources sooner than we expect. Changes may occur beyond our control that would cause us to consume our available capital before that time, including changes in and progress of our development activities, acquisitions of additional product candidates, and changes in regulation. Our future capital requirements will depend on many factors, including:

• the costs of and investment in ongoing and future development of our gene therapy product candidates;

• the scope, progress, costs and results of discovery, preclinical development, laboratory testing and clinical trials for our product candidates;

• the extent to which we develop, in-license or acquire other product candidates and technologies in our product candidate pipeline;

• the costs and timing of process development and manufacturing scale-up activities associated with our product candidates and other programs as we advance them through preclinical and clinical development;

• the number of, and development requirements for, product candidates that we may pursue;

• the costs, timing and outcome of regulatory review of our product candidates;

• our headcount growth and associated costs as we expand our research and development capabilities and establish a commercial infrastructure;

• the costs of establishing and maintaining commercial-scale cGMP manufacturing capabilities, either internally or with third parties;

• the costs and timing of future commercialization activities, including product manufacturing, marketing, sales and distribution, for any of our product candidates for which we receive marketing approval;

• the costs and timing of preparing, filing and prosecuting patent applications, maintaining and enforcing our intellectual property rights and defending any intellectual property-related claims;

• the revenue, if any, received from commercial sales of our product candidates for which we receive marketing approval;

• our ability to establish and maintain additional collaborations on favorable terms, if at all;

• the success of any collaborations that we may establish and our license agreements;

• the outcome of any legal proceedings involving us;

• the achievement of milestones or occurrence of other developments that trigger payments under our collaboration agreements or any additional collaboration agreements we may enter into; and

• the costs of operating as a public company.

We will require additional capital to achieve our business objectives. While the long-term economic impact of the ongoing geopolitical conflicts in Ukraine and the Middle East is difficult to assess or predict, each of these events has caused significant disruptions to the global financial markets and contributed to a general global economic slowdown. Furthermore, inflation rates, particularly in the United States, have increased recently to levels not seen in decades. Increased inflation may result in increased operating costs and may affect our operating budgets, specifically with respect to increased labor costs and associated difficulties in recruiting qualified personnel. In addition, the U.S. Federal Reserve has raised, and may further raise, interest rates in response to concerns about inflation. Increases in interest rates, especially if coupled with reduced government spending and volatility in financial markets, may further increase economic uncertainty and heighten these risks. If the disruptions and slowdown deepen or persist, we may not be able to access additional capital on favorable terms, or at all, which could in the future negatively affect our financial condition and we could be forced to curtail our planned operations and the pursuit of our growth strategy.

Raising additional capital may cause dilution to our stockholders, restrict our operations or require us to relinquish rights to our technologies or product candidates.

Until such time, if ever, as we can generate substantial revenue, we may finance our cash needs through a combination of equity offerings, government or private party grants, debt financings and license and collaboration agreements. We do not currently have any committed external source of funds. To the extent that we raise additional capital through the sale of equity or convertible debt securities, your ownership interest will be diluted, and the terms of these securities may include liquidation or other preferences that adversely affect your rights as a common stockholder. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting our ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends.

If we raise additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, we may be required to relinquish valuable rights to our technologies, future revenue streams or product candidates, grant licenses on terms that may not be favorable to us or commit to future payment streams. If we are unable to raise additional funds through equity or debt financings when needed, we may be required to delay, limit, reduce or terminate our product development or future commercialization efforts or grant rights to develop and market product candidates that we would otherwise prefer to develop and market ourselves.

Risks related to the development of our product candidates

Our business is dependent on our ability to advance our current and future product candidates through preclinical studies and clinical trials, obtain marketing approval and ultimately commercialize them. If we are unable to or experience significant delays in doing so, our business will be materially harmed.

We have invested a significant portion of our time and financial resources in the development of our product candidates and technology platforms. Our business is dependent on our ability to successfully complete preclinical and clinical development of, obtain regulatory approval for, and, if approved, successfully commercialize LX2006, LX2020 and any other product candidates in a timely manner.

Each of our product candidates and programs will require additional preclinical and/or clinical development, regulatory approval and significant marketing efforts, and we will be required to obtain manufacturing supply and expertise and to build a commercial organization or successfully outsource commercialization before we generate any revenue from product sales. We do not have any products that are approved for commercial sale, and we may never be able to develop or commercialize marketable products.

Our ability to generate revenue from our product candidates, which may not occur for several years, will depend heavily on the successful development, regulatory approval and eventual commercialization of our product candidates. The success of our lead product candidates, or any other product candidates that we develop or otherwise may acquire will depend on various factors, including:

• timely and successful completion of preclinical studies, including toxicology studies, biodistribution studies and minimally efficacious dose studies in animals, where applicable, under the FDA's good laboratory practices, or GLPs;

• the availability or development of suitable animal disease models for nonclinical studies to enable us to proceed into clinical development or support the submission of a marketing application;

• effective IND applications from the FDA or comparable foreign applications that allow commencement of our planned clinical trials or future clinical trials for our product candidates;

• sufficiency of our financial and other resources to complete the necessary preclinical studies and clinical trials;

• successful enrollment and completion of clinical trials, including under the FDA's current Good Clinical Practices, or cGCPs;

• establishment of our own manufacturing capabilities and/or arrangements with third-party manufacturers for our commercial manufacturing processes for any of our product candidates that receive regulatory approval;

• receipt of timely marketing approvals from applicable regulatory authorities;

• launch of commercial sales of products, if approved, whether alone or in collaboration with others;

• acceptance of the benefits and use of our products, including method of administration, if and when approved, by patients, the medical community and third-party payors, for their approved indications;

• the prevalence and severity of adverse events experienced with any of our product candidates;

• the availability, perceived advantages, cost, safety and efficacy of alternative therapies for any diseases for which we are developing our product candidates;

• our ability to produce our product candidates on a commercial scale;

• attainment and maintenance of patent, trademark and trade secret protection and regulatory exclusivity for our product candidates and otherwise protecting our rights in our intellectual property portfolio;

• maintenance of compliance with regulatory requirements such as cGMPs;

• attainment and maintenance of third-party coverage and adequate reimbursement for our product candidates and patients’ willingness to pay out-of-pocket in the absence of such coverage and adequate reimbursement; and

• maintenance of a continued acceptable safety, tolerability and efficacy profile of our products following approval.

If we are not successful with respect to one or more of these factors in a timely manner or at all, we could experience significant delays or an inability to successfully commercialize the product candidates we develop, which would materially harm our business. If we do not receive marketing approvals for any product candidate we develop, we may not be able to continue our operations.

We are developing novel gene therapy product candidates, which makes it difficult to predict the time, cost and potential success of product candidate development.

Our future success depends on the successful development of a novel therapeutic approach. To date, very few products that utilize gene transfer have been approved in the United States or Europe. There have been a limited number of clinical trials using AAVrh10. Although gene therapies have been studied in human clinical trials for over 30 years, only a limited number of AAV-based gene therapy products have been approved by the FDA.

We cannot be certain that our AAVrh10-based gene therapy product candidates will successfully complete clinical trials or that any future product candidates utilizing this or other vector constructs will successfully complete preclinical studies or clinical trials. We may not be successful in developing product candidates that avoid triggering toxicities or other side effects in preclinical studies or clinical trials. Our intravenous and intrathecal routes of administration may cause unforeseen side effects or present other challenges. Any such results could impact our ability to develop a product candidate, including our ability to enroll patients in our clinical trials. As a result of these factors, it is more difficult for us to predict the time and cost of product candidate development, and we cannot predict whether the application of our approach to gene therapy, or any similar or competitive programs, will result in the identification, development, and regulatory approval of any product candidate, or that other gene therapy programs will not be considered better or more favorable. There can be no assurance that any development problems we experience in the future related to our current gene therapy product candidates or any of our research programs will not cause significant delays or unanticipated costs, or that such development problems can be solved. We may also experience delays and challenges in achieving sustainable, reproducible, and scalable production. Any of these factors may prevent us from completing our preclinical studies or clinical trials or commercializing any product candidates we may develop on a timely or profitable basis, if at all.

Because gene therapy is novel and the regulatory landscape that governs any product candidates we may develop is rigorous, complex, uncertain and subject to change, we cannot predict with certainty the geographic areas in which we could obtain regulatory approval nor the time and cost of obtaining regulatory approval, if we receive it at all, for any product candidates we may develop.

The regulatory requirements that will govern any novel gene therapy product candidates we develop are not entirely clear and are subject to change. The novel nature of our capsids makes it difficult to determine how long it will take or how much it will cost to obtain regulatory approvals for our product candidates in the United States, the European Union or other jurisdictions. Within the broader genetic medicine field, very few gene therapy products have received marketing authorization from the FDA or the European Medicines Agency, or EMA. Even with respect to gene therapies, the regulatory landscape is still developing. Regulatory requirements governing gene therapy products have changed frequently and will likely continue to change in the future, including with respect to those responsible for regulation of existing gene therapy products. For example, in 2016, the FDA established the Office of Tissues and Advanced Therapies, or OTAT, within the Center for Biologics Evaluation and Research, or CBER, to consolidate the review of gene therapy and related products, and to advise the CBER on its review. In March 2023, the FDA retitled the OTAT to the Office of Therapeutic Products, or OTP, and elevated OTP to a “Super Office” to meet its growing cell and gene therapy workload.

Our product candidates will need to meet safety and efficacy standards applicable to any new biologic being pursued for a given disease under the regulatory framework administered by the FDA. Although the FDA decides whether individual gene therapy protocols may proceed, the review process and determinations of other reviewing bodies, including Institutional Review Boards, or IRBs, can impede or delay the initiation of a clinical trial.

The same applies in the European Union. The EMA’s Committee for Advanced Therapies, or CAT, is responsible for assessing the quality, safety and efficacy of advanced-therapy medicinal products. Advanced-therapy medicinal products include gene therapy medicines, somatic-cell therapy medicines and tissue-engineered medicines. The role of the CAT is to prepare a draft opinion on an application for marketing authorization for a gene therapy medicinal candidate that is submitted to the EMA. In the European Union, the development and evaluation of a gene therapy product must be considered in the context of the relevant EU guidelines. The EMA may issue new guidelines concerning the development and marketing authorization for gene therapy products and require that we comply with these new guidelines. This could mean that any gene therapy product candidate we may develop in the future could be required to comply with additional and/or more stringent gene therapy guidelines in the European Union.

Adverse developments in preclinical studies or clinical trials conducted by others in the field of gene therapy and gene regulation products may cause the FDA, the EMA and other regulatory bodies to revise the requirements for approval of any product candidates we may develop or limit the use of products utilizing gene regulation technologies, either of which could harm our business. In addition, the clinical trial requirements of the FDA, the EMA and other regulatory authorities and the criteria these regulators use to determine the safety and efficacy of a product candidate vary substantially according to the type, complexity, novelty, and intended use and market of the potential products. The regulatory approval process for product candidates such as ours can be more expensive and take longer than for other, better known, or more extensively studied pharmaceutical or other product candidates. Further, as we are developing novel potential treatments for diseases in which, in some cases, there is little clinical experience with potential new endpoints and methodologies, there is heightened risk that the FDA, the EMA or other regulatory bodies may not consider the clinical trial endpoints to provide clinically meaningful results, and the resulting clinical data and results may be more difficult to analyze. In addition, we may not be able to identify or develop appropriate animal disease models to enable or support planned clinical development. Any natural history studies that we may rely upon in our clinical development may not be accepted by the FDA, EMA or other regulatory authorities. Regulatory agencies administering existing or future regulations or legislation may not allow production and marketing of products utilizing gene regulation technology in a timely manner or under technically or commercially feasible conditions. In addition, regulatory action or private litigation could result in expenses, delays, or other impediments to our research programs or the commercialization of resulting products. Further, approvals by one regulatory agency may not be indicative of what other regulatory agencies may require for approval.

The regulatory review committees and advisory groups described above and any new guidelines they promulgate may lengthen the regulatory review process, require us to perform additional preclinical studies or clinical trials, increase our development costs, lead to changes in regulatory positions and interpretations, delay or prevent approval and commercialization of these treatment product candidates, or lead to significant post-approval limitations or restrictions. As we advance our research programs and develop future product candidates, we will be required to consult with these regulatory and advisory groups and to comply with applicable guidelines. If we fail to do so, we may be required to delay or discontinue development of any product candidates we identify and develop. These additional processes may result in a review and approval process that is longer than we otherwise would have expected. Delays as a result of an increased or lengthier regulatory approval process or further restrictions on the development of our product candidates can be costly and could negatively impact our ability to complete clinical trials and commercialize our current and future product candidates in a timely manner, if at all.

Preclinical studies and clinical trials are expensive, time-consuming, difficult to design and implement and involve an uncertain outcome. Further, we may encounter substantial delays in completing the development of our product candidates.

All of our product candidates are in preclinical or clinical development, and the risk of failure is high. The preclinical studies, clinical trials and manufacturing of our product candidates are, and the manufacturing and marketing of our products, if approved, will be, subject to extensive and rigorous review and regulation by numerous government authorities in the United States and in other countries where we may test and market our product candidates. Before obtaining regulatory approvals for the commercial sale of any of our product candidates, we must demonstrate through lengthy, complex and expensive preclinical testing and clinical trials that our product candidates are both safe and effective for use in each target disease. In particular, because our product candidates are subject to regulation as biologics, we will need to demonstrate that they are sufficiently safe and of sufficient purity and potency for use in their target diseases. Each product candidate must demonstrate an adequate risk-versus-benefit profile in its intended patient population and for its intended use.

Clinical testing is expensive, can take many years to complete and is subject to uncertainty. We cannot guarantee that any clinical trials will be initiated on schedule, conducted as planned or completed on schedule, if at all. To date, we are sponsoring clinical trials of LX2006 and LX2020, but we have not successfully completed any clinical trial that we have internally sponsored. Failure can occur at any time during the clinical trial process. Even if our ongoing and future clinical trials are completed as planned, we cannot be certain that their results will support the safety and effectiveness of our product candidates for their targeted diseases or support continued clinical development of such product candidates. Our future clinical trial results may not be successful.

In addition, even if such trials are successfully completed, we cannot guarantee that the FDA or foreign regulatory authorities will interpret the results as we do, and more trials could be required before we submit our product candidates for approval. This is particularly true for clinical trials in rare diseases, where the small patient populations make it difficult or impossible to conduct two traditional, adequate and well-controlled trials, and therefore the FDA or comparable foreign regulatory authorities are often required to exercise flexibility in approving therapies for such diseases. Moreover, results acceptable to support approval in one jurisdiction may be deemed inadequate by another regulatory authority to support regulatory approval in that other jurisdiction. To the extent that the results of the trials are not satisfactory to the FDA or foreign regulatory authorities for support of a marketing application, we may be required to expend significant resources, which may not be available to us, to conduct additional trials in support of potential approval of our product candidates.

We may experience delays in initiating and conducting clinical trials of our lead product candidates and we do not know whether our clinical trials will begin on time, need to be redesigned, recruit and enroll patients on time or be completed on schedule, or at all. Events that may prevent successful or timely completion of clinical development include:

• inability to generate sufficient preclinical, toxicology, or other in vivo or in vitro data to support the initiation of clinical trials;
• delays in sufficiently developing, characterizing or controlling a manufacturing process suitable for advanced clinical trials;
• delays in sourcing or qualifying ancillaries required for administration of our clinical drug product (such as vials, stoppers, or tubing);
• delays in developing suitable assays for screening patients for eligibility for trials with respect to certain product candidates;
• delays in reaching agreement with the FDA, EMA or other regulatory authorities as to the design or implementation of our clinical trials;
• failure to obtain regulatory approval to commence a clinical trial;
• failure to reach an agreement on acceptable terms with clinical trial sites or prospective CROs, the terms of which can be subject to extensive negotiation and may vary significantly among different clinical trial sites;
• inability to obtain IRB approval for each clinical trial site;
• inability to recruit suitable patients to participate in a clinical trial in a timely manner;
• failure to have patients complete a clinical trial or return for post-treatment follow-up;
• deviations by clinical trial sites, CROs or other third parties from trial protocol;
• failure to perform our planned clinical trials in accordance with the FDA’s cGCP requirements, or applicable regulatory guidelines in other countries;
• inability to address patient-safety concerns that arise during the course of a trial, including occurrence of adverse events associated with the product candidate that are viewed to outweigh its potential benefits;
• failure to initiate a sufficient number of clinical trial sites; or
• delays in manufacturing sufficient quantities of a product candidate for use in clinical trials.

We may experience numerous unforeseen events during, or as a result of, clinical trials that could delay or prevent our ability to receive marketing approval or commercialize our product candidates or significantly increase the cost of such trials, including:

• we may experience changes in regulatory requirements or guidance, or receive feedback from regulatory authorities, that require us to modify the design of our clinical trials;

• clinical trials of our product candidates may produce negative or inconclusive results, and we may decide, or regulators may require us, to conduct additional clinical trials or halt development programs;

• the number of patients required for clinical trials of our product candidates may be larger than we anticipate, enrollment in these clinical trials may be slower than we anticipate, or participants may drop out of these clinical trials at a higher rate than we anticipate;

• our third-party contractors may fail to comply with regulatory requirements or meet their contractual obligations to us in a timely manner, or at all;

• we, our investigators or regulators may suspend or terminate clinical trials of our product candidates for various reasons, including non-compliance with regulatory requirements, a finding that our product candidates have undesirable side effects or other unexpected characteristics, or a finding that the participants are being exposed to unacceptable health risks;

• the cost of clinical trials of our product candidates may be greater than we anticipate, and we may not have funds to cover the costs;

• the supply or quality of our product candidates or other materials necessary to conduct clinical trials of our product candidates may be insufficient or inadequate;

• regulators may revise the requirements for approving our product candidates, or such requirements may not be as we anticipate; and

• any future collaborators that conduct clinical trials may face any of the above issues and may conduct clinical trials in ways they view as advantageous to them but that are suboptimal for us.

If we are required to conduct additional clinical trials or other testing of our product candidates beyond those that we currently contemplate, if we are unable to successfully initiate or complete clinical trials of our product candidates or other testing, if the results of these trials or tests are not positive or are only modestly positive or if there are safety concerns, we may:

• incur unplanned costs;
• be delayed in obtaining marketing approval for our product candidates or not obtain marketing approval at all;
• obtain marketing approval in some countries and not in others;
• obtain marketing approval for diseases or patient populations that are not as broad as intended or desired;
• obtain marketing approval with labeling that includes significant use or distribution restrictions or safety warnings, including boxed warnings Risk Evaluation and Mitigation Strategies, or REMS;
• be subject to additional post-marketing testing requirements; or
• have the product removed from the market after obtaining marketing approval.

We could encounter delays if a clinical trial is suspended or terminated by us, by the IRBs of the institutions in which such trials are being conducted, by the Data Safety Monitoring Board for such trial or by the FDA, EMA or other regulatory authorities. Such authorities may impose such a suspension or termination due to a number of factors, including failure to conduct the clinical trial in accordance with regulatory requirements or our clinical protocols, inspection of the clinical trial operations or trial site by the FDA, EMA or other regulatory authorities resulting in the imposition of a clinical hold, unforeseen safety issues or adverse side effects, failure to demonstrate a benefit from using a drug, changes in governmental regulations or administrative actions or lack of adequate funding to continue the clinical trial.

All of our product candidates will require extensive clinical testing before we are prepared to submit a biologics license application, or BLA, or marketing authorization application, or MAA, for regulatory approval. We cannot predict with any certainty if or when we might complete the clinical development for our product candidates and submit a BLA or MAA for regulatory approval of any of our product candidates or whether any such BLA or MAA will be approved. We may also seek feedback from the FDA, EMA or other regulatory authorities on our clinical development program, and the FDA, EMA or such regulatory authorities may not provide such feedback on a timely basis, or such feedback may not be favorable, which could further delay our development programs.

We cannot predict with any certainty whether or when we might complete a given clinical trial. If we experience delays in the commencement or completion of our clinical trials, or if we terminate a clinical trial prior to completion, the commercial prospects of our product candidates could be harmed, and our ability to generate revenues from our product candidates may be delayed or lost. In addition, any delays in our clinical trials could increase our costs, slow down the development and approval process and jeopardize our ability to commence product sales and generate revenues. Any of these occurrences may harm our business, financial condition and results of operations. In addition, many of the factors that cause, or lead to, a delay in the commencement or completion of clinical trials may also ultimately lead to the denial of regulatory approval of our product candidates.

The regulatory approval processes of the FDA, EMA and comparable foreign authorities are lengthy, time-consuming and inherently unpredictable. If we are not able to obtain required regulatory approval for our product candidates, our business will be substantially harmed.

The time required to obtain approval or other marketing authorizations by the FDA, EMA and comparable foreign authorities is unpredictable, and it typically takes many years following the commencement of clinical trials and depends upon numerous factors, including the substantial discretion of the regulatory authorities. In addition, approval policies, regulations, and the type and amount of clinical data necessary to gain approval may change during the course of a product candidate’s clinical development and may vary among jurisdictions. We have not obtained regulatory approval for any product candidate, and it is possible that we may never obtain regulatory approval for any product candidates we may seek to develop in the future. Neither we nor any collaborator is permitted to market any of our biologic product candidates in the United States until we receive regulatory approval of a BLA from the FDA, and we cannot market any of our product candidates in the European Union until we receive approval for an MAA from the EMA, or other required regulatory approval in other countries.

Prior to obtaining approval to commercialize any product candidate in the United States or abroad, we must demonstrate with substantial evidence from well-controlled clinical trials, and to the satisfaction of the FDA or foreign regulatory agencies, that such product candidates are safe, effective and of sufficient purity for their intended uses. Results from preclinical studies and clinical trials can be interpreted in different ways. Even if we believe the preclinical or clinical data for our product candidates meet regulatory standards, such data may not be sufficient to support approval by the FDA and other regulatory authorities. The FDA may also require us to conduct additional preclinical studies or clinical trials for our product candidates either prior to or after approval, or it may object to elements of our clinical development programs, or require changes to our manufacturing approaches.

Of the large number of products in development, only a small percentage successfully complete the FDA or foreign regulatory approval processes and are commercialized. The lengthy approval and marketing authorization process as well as the unpredictability of future clinical trial results may result in our failing to obtain regulatory approval and marketing authorization to market our product candidates, which would significantly harm our business, financial condition, results of operations and prospects.

We have invested a significant portion of our time and financial resources in the development of our product candidates and technology platforms. Our business is dependent on our ability to successfully complete preclinical and clinical development of, obtain regulatory approval for, and, if approved, successfully commercialize LX2006, LX2020, and our other product candidates in a timely manner.

Even if we eventually complete clinical testing and receive approval of a BLA or foreign marketing application for any of our product candidates, the FDA, EMA or the applicable foreign regulatory agency may grant approval or other marketing authorization contingent on the performance of costly additional clinical trials, including post-marketing clinical trials. The FDA, EMA or the applicable foreign regulatory agency also may approve or authorize for marketing a product candidate for a more limited disease or patient population than we originally request, and the FDA, EMA or applicable foreign regulatory agency may not approve or authorize the labeling that we believe is necessary or desirable for the successful commercialization of a product candidate. Any delay in obtaining, or inability to obtain, applicable regulatory approval or other marketing authorization would delay or prevent commercialization of that product candidate and would materially adversely impact our business and prospects.

In addition, the FDA, EMA and other regulatory authorities may change their policies, issue additional regulations or revise existing regulations, or take other actions, which may prevent or delay approval of our future products under development on a timely basis. Such policy or regulatory changes could impose additional requirements upon us that could delay our ability to obtain approvals, increase the costs of compliance or restrict our ability to maintain any marketing authorizations we may have obtained. In June 2024, the Supreme Court overruled the Chevron doctrine, which had given deference to regulatory agencies’ statutory interpretations of ambiguous regulations in litigation against federal government agencies, such as the FDA. The overruling of the Chevron doctrine may significantly increase the number of challenges brought by companies and other stakeholders against federal agencies such as the FDA and its longstanding decisions and policies, including the FDA’s statutory interpretations of market exclusivities and the “substantial evidence” requirements for drug approvals, which could undermine the FDA’s authority, lead to uncertainties in the industry, and disrupt the FDA’s normal operations, any of which could delay the FDA’s review of our regulatory submissions. We cannot predict the full impact of this decision, future judicial challenges brought against the FDA, or the nature or extent of government regulation that may arise from future legislation or administrative action.

Further, under the current administration, agency reorganization, government shutdown, lapse in government appropriation, voluntary departures at the FDA, and layoffs due to the reduction in force initiative and other measures implemented by the Department of Government Efficiency may impact the normal operations of the FDA as well as other federal agencies. FDA may lack adequate staff and resources to meet current review, approval, and inspection schedules, which could delay our anticipated timelines. In January 2025, an executive order entitled “Unleashing Prosperity Through Deregulation”, was issued which calls for at least 10 existing regulations to be repealed whenever an executive department or agency publicly proposes for notice and comment or otherwise promulgates a new regulation. Recent developments at the FDA include announcement of a plan to phase out animal testing for monoclonal antibodies and certain other drugs and the announcement of a new Commissioner’s National Priority Voucher program for companies supporting certain U.S. national health priorities and interests. To the extent our competitors are selected for this new voucher pilot program and obtain faster approval than us, our competitive position may be harmed. FDA has also increased its scrutiny of foreign drug manufacturing facilities and other contractors based in China, especially with respect to the transfer of biological materials, genetic data, and other sensitive data of American patients to parties located in China. FDA’s “real-time” release of newly issued Complete Response Letters associated with withdrawn or abandoned applications, if received for any of our product candidates, can materially impact our competitive advantage and intellectual property. It is unclear how our industry and our clinical programs will be impacted by the current government shutdown, policies and regulations implemented under the current administration and FDA leadership, or other executive orders. There is significant uncertainty in the industry and how federal agencies like the FDA will change in the coming years under the current administration. To the extent the agency reorganization and other agency changes lead to disruptions in FDA’s operations, our correspondence and regulatory review processes with the FDA may be materially delayed.

Success in preclinical studies or earlier clinical trials may not be indicative of results in future clinical trials.

Success in preclinical testing and early clinical trials does not ensure that later clinical trials will generate the same results or otherwise provide adequate data to demonstrate the efficacy and safety of a product candidate. Preclinical tests and Phase 1 and Phase 2 clinical trials are primarily designed to test safety, to study pharmacokinetics and pharmacodynamics and to understand the side effects of product candidates at various doses and schedules. Success in preclinical or animal studies and early clinical trials does not ensure that later larger-scale efficacy and safety trials will be successful, nor does it predict final results. For example, we may be unable to identify suitable animal disease models for our product candidates, which could delay or frustrate our ability to proceed into clinical trials or obtain marketing approval. In addition, the preclinical studies conducted by Stelios (an entity that we acquired in 2021) and The Regents of UCSD for our product candidates LX2021 and LX2022 employed an AAV9-based formulation and studies using this vector may not be predictive of future testing we intend to conduct using an AAVrh10-based formulation or other potential capsid serotypes.

Our product candidates may fail to show the desired safety and efficacy in clinical development despite positive results in preclinical studies or having successfully advanced through initial clinical trials. Furthermore, our currently ongoing and most future clinical trials involve or will involve a small patient population. Because of the small sample sizes studied in our trials thus far, the results of these trials may not be indicative of results of future clinical trials.

Additionally, some of our ongoing and planned clinical trials utilize, or may utilize, an “open-label” trial design. An “open-label” clinical trial is one where both the patient and investigator know whether the patient is receiving the investigational product candidate or either an existing approved drug or placebo. Most typically, open-label clinical trials test only the investigational product candidate and sometimes may do so at different dose levels. Open-label clinical trials are subject to various limitations that may exaggerate any therapeutic effect as patients in open-label clinical trials are aware when they are receiving treatment. Open-label clinical trials may be subject to a “patient bias” where patients perceive their symptoms to have improved merely due to their awareness of receiving an experimental treatment. In addition, open-label clinical trials may be subject to an “investigator bias” where those assessing and reviewing the physiological outcomes of the clinical trials are aware of which patients have received treatment and may interpret the information of the treated group more favorably given this knowledge. The results from an open-label trial may not be predictive of future clinical trial results when studied in a controlled environment with a placebo or active control.

Many companies in the pharmaceutical and biotechnology industries have suffered significant setbacks in late-stage clinical trials even after achieving promising results in preclinical testing and earlier-stage clinical trials. Data obtained from preclinical and clinical activities are subject to varying interpretations, which may delay, limit, or prevent regulatory approval. In addition, we may experience regulatory delays or rejections as a result of many factors, including changes in regulatory policy during the period of our product candidate development. Any such delays could negatively impact our business, financial condition, results of operations and prospects.

Interim “top-line” and preliminary results from our clinical trials that we announce, publish or present from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

From time to time, we have and may continue to publish or present interim top-line or preliminary results from our clinical trials. Interim results from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as patient enrollment continues and more patient data become available. Preliminary or top-line results also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we previously published. As a result, interim and preliminary data should be viewed with caution until the final data are available. Differences between preliminary or interim data and final data could significantly harm our business prospects and may cause the trading price of our common stock to fluctuate significantly.

Our preclinical studies and clinical trials may fail to demonstrate the safety and efficacy of our product candidates, or serious adverse or unacceptable side effects may be identified during the development of our product candidates, which could prevent or delay regulatory approval and commercialization, increase our costs or necessitate the abandonment or limitation of the development of some of our product candidates. We may also identify safety and efficacy concerns after the approval of a product candidate which can result in negative consequences to our business and results of operations.

Before obtaining regulatory approvals for the commercial sale of our product candidates, we must demonstrate through lengthy, complex and expensive preclinical testing and clinical trials that our product candidates are safe, effective and of sufficient purity for use in each target disease, and failures can occur at any stage of testing. Preclinical studies and clinical trials often fail to demonstrate safety or efficacy of the product candidate studied for the target disease. While we have developed our AAVrh10-mediated gene therapy product candidates to leverage the low seropositivity of AAVrh10, any gene therapy product based on viral vectors carries the risks of immunogenicity, elevated liver enzymes and insertional oncogenesis, which is the process whereby the insertion of a functional gene near a gene that is important in cell growth or division results in uncontrolled cell division, which could potentially enhance the risk of malignant transformation. In one of our preclinical studies of LX2006, we observed four cases of hepatocellular carcinoma, or HCC, in wild-type mice at 10 months post-treatment. Although data reported by the FDA Cellular, Tissue, and Gene Therapies Advisory Committee in September 2021 suggests that HCC observed in mice after AAV treatment is unlikely to translate to risks for humans, any future instances of HCC in our clinical trials could result in delays or the abandonment of our trials. Health authorities also ask that sponsors closely monitor the risk of elevated liver enzymes and abnormal liver ultrasound on a routine basis in patients participating in gene therapy clinical trials.

Possible adverse side effects that could occur with treatment with gene therapy products include an immunologic reaction early after administration, which, while not necessarily adverse to the patient’s health, could substantially limit the effectiveness of the treatment. For example, in previous third-party clinical trials involving AAV capsids for gene therapy, some subjects experienced the development of a T-cell antibody response, whereby after the vector is within the target cell types, the cellular immune response system triggers the removal of transduced cell types by activated T-cells. If any of our product candidates demonstrate a similar effect, we may decide or be required to perform additional preclinical studies or to halt or delay further clinical development of our product candidates.

In addition to side effects caused by the product candidate, the administration process or related procedures also can cause adverse side effects. Our APOE-associated Alzheimer’s disease product candidates are designed to be delivered via intracisternal administration. While the intracisternal method of administration has been available for some years, its use for gene therapies is new and no gene therapy is currently approved for this method of administration. Intracisternal administration may have greater risk and/or be perceived as having greater risk than more common methods of administration, such as intravenous injection. Other gene therapy product candidates in clinical development utilizing intracisternal delivery could also generate data that could adversely affect the clinical, regulatory or commercial perception of our product candidates.

If adverse events occur, either as a result of the product candidate or administration process, our clinical trials could be suspended or terminated. If we cannot demonstrate that any adverse events were not caused by the drug or administration process or related procedures, the FDA, EMA or foreign regulatory authorities could order us to cease further development of, or deny approval of, our product candidates for any or all targeted diseases. Even if we are able to demonstrate that serious adverse events are not product-related, such occurrences could affect patient recruitment or the ability of enrolled patients to complete the trial. Moreover, if we elect, or are required, to not initiate, delay, suspend or terminate any future clinical trial of any of our product candidates, the commercial prospects of such product candidates may be harmed and our ability to generate product revenues from any of these product candidates may be delayed or eliminated. Any of these occurrences may harm our ability to develop other product candidates, and may harm our business, financial condition and prospects significantly. Furthermore, negative results in our development of LX2006 or LX2020 could be interpreted as a failure to achieve proof of concept for our technology and result in the abandonment of other development programs.

In addition, gene therapy is still a relatively new approach to disease treatment and additional adverse side effects could develop. There also is the potential risk of delayed adverse events following exposure to gene therapy products due to persistent biologic activity of the genetic material or other components of products used to carry the genetic material. If our product candidates are associated with side effects in clinical trials or have characteristics that are unexpected, we may need to abandon their development or limit development to more narrow uses in which the side effects or other characteristics are less prevalent, less severe or more acceptable from a risk-benefit perspective. The FDA or an IRB may also require that we suspend, discontinue, or limit our clinical trials based on safety information, or that we conduct additional animal or human studies regarding the safety and efficacy of our product candidates which we have not planned or anticipated. Such findings could further result in regulatory authorities failing to provide marketing authorization for our product candidates or limiting the scope of the approved indication, if approved. Many product candidates that initially showed promise in early-stage testing have later been found to cause side effects that prevented further development of the product candidate.

Additionally, if one or more of our product candidates receives marketing approval, and we or others identify undesirable side effects caused by such products or the administration procedure, a number of potentially significant negative consequences could result, including:

• regulatory authorities may withdraw approvals of such product;
• regulatory authorities may require additional warnings on the labels;
• we may be required to create a medication guide outlining the risks of such side effects for distribution to patients or other requirements subject to a REMS;
• we could be sued and held liable for harm caused to patients;
• we may not be able to obtain or maintain third-party payor coverage and adequate reimbursement; and
• our reputation and physician or patient acceptance of our products may suffer.

There can be no assurance that we will resolve any issues related to any product-related adverse events to the satisfaction of the FDA or foreign regulatory agency in a timely manner or at all. Moreover, any of these events could prevent us from achieving or maintaining market acceptance of the particular product candidate, if approved, and could significantly harm our business, results of operations and prospects.

Some of the diseases we initially seek to treat have low prevalence and it may be difficult to identify and enroll patients with these diseases. If we experience delays or difficulties in the enrollment and/or maintenance of patients in clinical trials, our receipt of necessary regulatory approvals could be delayed or prevented.

Successful and timely completion of clinical trials will require that we enroll a sufficient number of patients. Patient enrollment, a significant factor in the timing of clinical trials, is affected by many factors, including the size and nature of the patient population and competition for patients with other trials. The rare genetic diseases which some of our product candidates are designed to target have low incidence and prevalence and may be difficult to diagnose. In particular, because we are focused on patients with specific genetic mutations, our ability to enroll eligible patients may be limited or enrollment may be slower than we anticipate. For example, we estimate that approximately 6,600 people in the United States have FA and that approximately 80% of these patients will develop the cardiac manifestation of FA, or FA cardiomyopathy, and accordingly it may be difficult for us to identify and timely recruit a sufficient number of eligible patients to conduct our clinical trials. While the patient population for LX2020, our program targeting PKP2-ACM, is significantly larger than FA, we may face challenges in identifying and recruiting eligible patients to conduct our clinical trial given competing clinical trials. Even for more prevalent conditions such as Alzheimer’s disease, it may be difficult to recruit patients to clinical trials due to the number of approved products, difficulty identifying patients with the specific genotype we are studying, and the number of clinical trials being conducted in this indication.

Our trials may be subject to delays as a result of patient enrollment taking longer than anticipated or patient withdrawal. We may not be able to initiate or continue clinical trials for our product candidates if we are unable to locate and enroll a sufficient number of eligible patients to participate in these trials as required by the FDA, EMA or other foreign regulatory authorities. We cannot predict how successful we will be at enrolling subjects in future clinical trials. Subject enrollment is affected by other factors including:

• the severity of the disease under investigation;

• the eligibility criteria for the trial in question;

• the size of the patient population and process for identifying patients;

• the perceived risks and benefits of the product candidate under study;

• clinicians’ and patients’ perceptions as to the potential advantages of the product candidate being studied in relation to other available therapies, including any new drugs that may be approved for the diseases we are investigating;

• the availability of competing commercially available therapies and other competing therapeutic product candidates’ clinical trials;

• the efforts to facilitate timely enrollment in clinical trials;

• the risk that patients enrolled in clinical trials will drop out of the clinical trials before completion of their treatment;

• the patient referral practices of physicians;

• the ability to monitor patients adequately during and after treatment; and

• the proximity and availability of clinical trial sites for prospective patients.

Our inability to enroll a sufficient number of patients for clinical trials would result in significant delays and could require us to abandon one or more clinical trials altogether. Enrollment delays in these clinical trials may result in increased development costs for our product candidates, which would cause the value of our company to decline and limit our ability to obtain additional financing. Furthermore, we rely on CROs and clinical trial sites to help ensure the proper and timely conduct of our clinical trials and we may have limited influence over their performance. For additional information, see the risk factor in this section under the heading “We intend to continue to rely on third parties to conduct a significant portion of our existing clinical trials and potential future clinical trials for product candidates, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials.”

Furthermore, even if we are able to enroll a sufficient number of patients for our clinical trials, we may have difficulty maintaining enrollment of such patients in our clinical trials.

We may seek Orphan Drug designation or Rare Pediatric Disease designation for some of our product candidates and we may be unsuccessful, or may be unable to maintain the benefits associated with Orphan Drug designation, including the potential for market exclusivity, for product candidates for which we obtain Orphan Drug designation.

Regulatory authorities in some jurisdictions, including the United States, may designate drugs or biologics intended to treat relatively small patient populations as orphan drug products. Under the Orphan Drug Act, the FDA may designate a drug or biologic as an orphan drug if it is intended to treat a rare disease or condition, which is generally defined as a patient population of fewer than 200,000 individuals in the United States, or a patient population of 200,000 or more in the United States where there is no reasonable expectation that the cost of developing the drug will be recovered from sales in the United States.

In the United States, Orphan Drug designation entitles a party to potential financial incentives such as tax advantages and user fee waivers. Opportunities for grant funding toward clinical trial costs may also be available for clinical trials of drugs or biologics for rare diseases, regardless of whether the drugs or biologics are designated for the orphan use. In addition, if a drug or biologic with an Orphan Drug designation subsequently receives the first marketing approval for the disease for which it has such designation, the product is entitled to a seven-year period of marketing exclusivity, which precludes the FDA from approving another marketing application for the same drug and disease for that time period, except in limited circumstances. If our competitors are able to obtain orphan drug exclusivity prior to us, for products that constitute the “same drug” and treat the same diseases as our product candidates, we may not be able to have competing products approved by the applicable regulatory authority for a significant period of time.

Similarly, in the European Union, the European Commission, upon the recommendation of the EMA’s Committee for Orphan Medicinal Products, grants Orphan Drug designation to promote the development of drugs that are intended for the diagnosis, prevention or treatment of life-threatening or chronically debilitating conditions and either the prevalence of the condition is not more than 5 in 10,000 persons in the European Union, or, without incentives, it is unlikely that sales of the drug in the European Union would be sufficient to justify the necessary investment in developing the drug. In each case, there must be no satisfactory method of diagnosis, prevention or treatment of the condition that has been authorized, or, if such a method exists, the product in question must be of significant benefit to those affected by such condition. In the European Union, Orphan Drug designation entitles a party to financial incentives such as reduction of fees or fee waivers.

We have obtained from the FDA Orphan Drug designation for LX2006 for the treatment of FA and for LX2020 for the treatment of PKP2-ACM. LX2006 and LX2020 have also received Orphan Medicinal Product designation from the European Commission. We may seek orphan designation for some or all of our product candidates in orphan indications in which there is a medically plausible basis for the use of these product candidates. However, we may be unsuccessful in obtaining Orphan Drug designation and may be unable to maintain the benefits associated with such designations. Even if we obtain orphan drug exclusivity for any of our product candidates, that exclusivity may not effectively protect those product candidates from competition because different drugs can be approved for the same condition, and orphan drug exclusivity does not prevent the FDA from approving the same or a different drug in another indication. Even after an orphan drug is granted orphan exclusivity and approved, the FDA can subsequently approve a later application for the same drug for the same condition before the expiration of the seven-year exclusivity period if the FDA concludes that the later drug is clinically superior in that it is shown to be safer in a substantial portion of the target populations, more effective or makes a major contribution to patient care. On August 3, 2017, Congress passed the FDA Reauthorization Act of 2017, or FDARA. FDARA, among other things, codified the FDA’s preexisting regulatory interpretation, to require that a drug sponsor demonstrate the clinical superiority of an orphan drug that is otherwise the same as a previously approved drug for the same rare disease in order to receive orphan drug exclusivity. The statute supplants prior precedent holding that the Orphan Drug Act unambiguously requires that the FDA recognize the orphan exclusivity period regardless of a showing of clinical superiority. Moreover, in the Consolidated Appropriations Act of 2021, Congress clarified that the interpretation of orphan drug exclusivity codified in FDARA would apply in cases where the FDA issued an orphan designation before the enactment of FDARA but where product approval came after the enactment of FDARA. In addition, a designated Orphan Drug may not receive orphan drug exclusivity if it is approved for a use that is broader than the disease for which it received orphan designation. In Catalyst Pharms., Inc. v. Becerra, 14 F.4th 1299 (11th Cir. 2021), the court disagreed with the FDA’s longstanding position that orphan drug exclusivity only applies to the approved use or indication within an eligible disease. This decision created uncertainty in the application of orphan drug exclusivity. In January 2023, the FDA published a notice in the Federal Register to clarify that while the agency complies with the court’s order in Catalyst, the FDA intends to continue to apply its longstanding interpretation of the regulations to matters outside of the scope of the Catalyst order – that is, the agency will continue tying the scope of orphan-drug exclusivity to the uses or indications for which a drug is approved, which permits other sponsors to obtain approval of a drug for new uses or indications within the same orphan designated disease or condition that have not yet been approved. In view of the overturn of the Chevron doctrine in Loper Bright Enterprises v. Raimondo, this landmark Supreme Court decision may invite various stakeholders to bring lawsuits against the FDA to challenge longstanding decisions and policies, including regulatory exclusivities, which could lead to uncertainties in the industry. Further, changes in the leadership of the FDA and other federal agencies under the current administration may lead to new policies and changes in the regulations and operations of the FDA, which may impact our clinical development plans. We do not know if, when, or how the FDA, Congress, or future judicial challenges may change the orphan drug regulations and policies in the future, and it is uncertain how any changes might affect our business. Depending on what changes the FDA may make to its orphan drug regulations and policies, our business could be adversely impacted. Moreover, orphan drug-exclusive marketing rights in the United States may be lost if the FDA later determines that the request for designation was materially defective or if we are unable to manufacture sufficient quantities of the product to meet the needs of patients with the rare disease or condition. Orphan Drug designation neither shortens the development time or regulatory review time of a drug nor gives the drug any advantage in the regulatory review or approval process.

Fast Track, Breakthrough Therapy, or Regenerative Medicine Advanced Therapy designation that we may receive from the FDA may not actually lead to a faster development or regulatory review or approval process, and does not assure FDA approval of our product candidates.

We may seek Fast Track, Breakthrough Therapy or Regenerative Medicine Advanced Therapy, or RMAT, designation from the FDA for some or all of our product candidates, but we may be unable to obtain such designations or to maintain the benefits associated with such designations. The FDA’s Fast Track, Breakthrough Therapy, and RMAT designation programs are intended to expedite the development of certain qualifying product candidates intended for the treatment of serious diseases and conditions. If a product candidate is intended for the treatment of a serious or life- threatening condition and preclinical or clinical data demonstrate the product’s potential to address an unmet medical need for this condition, the sponsor may apply for FDA Fast Track designation.

A product candidate may be designated as a breakthrough therapy if it is intended, alone or in combination with one or more other drugs or biologics to treat a serious or life-threatening condition and preliminary clinical evidence indicates that the product candidate may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints. For product candidates that have been designated as breakthrough therapies, interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens. Drugs and biologics designated as breakthrough therapies by the FDA may also be eligible for accelerated approval.

A product candidate may receive RMAT designation if it is a regenerative medicine therapy that is intended to treat, modify, reverse or cure a serious or life-threatening disease or condition, and preliminary clinical evidence indicates that the product candidate has the potential to address an unmet medical need for such condition. RMAT designation allows companies developing regenerative medicine therapies to work more closely and frequently with the FDA, and RMAT-designated product candidates may be eligible for priority review and accelerated approval. FDA has confirmed that gene therapies, including genetically modified cells, that lead to a sustained effect on cells or tissues may meet the definition of a regenerative medicine therapy. For product candidates that have received an RMAT designation, interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens.

We have received Fast Track designation for LX2006 for the treatment of FA cardiomyopathy, and for LX2020 for the treatment of PKP2-ACM. We have also received Breakthrough Therapy designation for LX2006 for the treatment of FA cardiomyopathy as well as RMAT designation for LX2006 for the treatment of FA cardiomyopathy. LX2006 has also been selected by the FDA to participate in its Chemistry, Manufacturing, and Controls Development and Readiness Pilot, or CDRP, program, which is intended to facilitate expedited CMC development of investigational therapies with expedited clinical development timeframes via an increased level of communication with the FDA on CMC development. While we may seek Fast Track, Breakthrough Therapy and/or RMAT designation, or participation in the CDRP program, for some or all of our product candidates, there is no guarantee that we will be successful in obtaining any such designation. Even if we do obtain such designation, we may not experience a faster development process, review or approval compared to conventional FDA procedures. A Fast Track, Breakthrough Therapy, or RMAT designation, or participation in the CDRP program, does not ensure that the product candidate will receive marketing approval or that approval will be granted within any particular time frame. In addition, the FDA may withdraw Fast Track, Breakthrough Therapy, or RMAT designation, or remove a product candidate from the CDRP program, if it believes that the designation is no longer supported by data from our clinical development program. Fast Track, Breakthrough Therapy and/or RMAT designation, or participation in the CDRP program, alone, does not guarantee qualification for the FDA’s priority review procedures.

We have received Rare Pediatric Disease designation from the FDA for LX2006 for the treatment of FA and we may seek such designation for future product candidates. However, a marketing application for these product candidates, if approved, may not meet the eligibility criteria for a rare pediatric disease priority review voucher.

We have received Rare Pediatric Disease designation from the FDA for LX2006 for the treatment of FA and LX1004 for the treatment of CLN2 disease and we may seek Rare Pediatric Disease designation for future product candidates. The FDA defines “rare pediatric disease” as a (i) serious or life-threatening disease in which the serious or life-threatening manifestations primarily affect individuals aged from birth to 18 years, including age groups often called neonates, infants, children, and adolescents; and (ii) a rare disease or condition within the meaning of the Orphan Drug Act. Designation of a product candidate as a product for a rare pediatric disease does not guarantee that a marketing application for such product candidate will meet the eligibility criteria for a rare pediatric disease priority review voucher at the time the application is approved. Under the U.S. Federal Food, Drug, and Cosmetic Act, or FDCA, we will need to request a rare pediatric disease priority review voucher in our original marketing application for our product candidates for which we have received Rare Pediatric Disease designation. The FDA may determine that a marketing application for any such product candidates, if approved, does not meet the eligibility criteria for a priority review voucher, including for the following reasons:

• the rare pediatric disease that received such designation no longer meets the definition of a “rare pediatric disease”;
• the marketing application contains an active ingredient (including any ester or salt of the active ingredient) that has been previously approved in a marketing application;
• the marketing application is not deemed eligible for priority review;
• the marketing application does not rely on clinical data derived from studies examining a pediatric population and dosages of the product intended for that population (that is, if the marketing application does not contain sufficient clinical data to allow for adequate labeling for use by the full range of affected pediatric patients); or
• the marketing application is approved for a different adult indication than the rare pediatric disease for which our product candidates are designated.

Under the current statutory sunset provisions, after September 30, 2024, the FDA may only award a priority review voucher, or PRV, for an approved rare pediatric disease product application if the sponsor has Rare Pediatric Disease designation for the drug or biologic that is the subject of such application, and that designation was granted by September 30, 2024. After September 30, 2026, the FDA may not award any rare PRVs. However, it is possible the authority for FDA to award rare pediatric disease PRVs will be further extended by Congress. As such, if we do not obtain approval of a marketing application for LX2006 in patients with FA on or before September 30, 2026, and if the PRV program is not extended by Congressional action, we may not receive a PRV. Congress did not reauthorize the rare pediatric disease priority review program at the end of 2024, and it is unclear whether the Congress under the current administration will extend the program.

Where appropriate, we may seek approval from the FDA, EMA or comparable foreign regulatory authorities through the use of accelerated approval pathways. If we are unable to obtain such approval, we may be required to conduct additional preclinical studies or clinical trials beyond those that we contemplate, which could increase the expense of obtaining, and delay the receipt of, necessary marketing approvals. Even if we receive accelerated approval from the FDA, EMA or comparable regulatory authorities, if our confirmatory trials do not verify clinical benefit, or if we do not comply with rigorous post-marketing requirements, the FDA, EMA or such other regulatory authorities may seek to withdraw accelerated approval.

Where possible, we may pursue accelerated development strategies in areas of high medical need. We may seek an accelerated approval pathway for one or more of our therapeutic product candidates from the FDA, EMA or comparable foreign regulatory authorities. Under the accelerated approval provisions in the FDCA and the FDA’s implementing regulations, the FDA may grant accelerated approval to a therapeutic candidate that is designed to treat a serious or life-threatening condition, generally provides a meaningful therapeutic benefit over available therapies, and demonstrates an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit or on a clinical endpoint that can be measured earlier than irreversible morbidity or mortality, or IMM, that is reasonably likely to predict an effect on IMM or other clinical benefit. The FDA considers a clinical benefit to be a positive therapeutic effect that is clinically meaningful in the context of a given disease, such as IMM. For the purposes of accelerated approval, a surrogate endpoint is a marker, such as a laboratory measurement, radiographic image, physical sign, or other measure that is thought to predict clinical benefit, but is not itself a measure of clinical benefit. An intermediate clinical endpoint is a clinical endpoint that can be measured earlier than an effect on IMM that is reasonably likely to predict an effect on IMM or other clinical benefit. The accelerated approval pathway may be used in cases in which the advantage of a new product over available therapy may not be a direct therapeutic advantage, but is a clinically important improvement from a patient and public health perspective. If granted, accelerated approval is usually contingent on the sponsor’s agreement to conduct, in a diligent manner, additional post-approval confirmatory studies to verify and describe the product’s clinical benefit. If such post-approval studies fail to confirm the product’s clinical benefit, the FDA may withdraw its approval of the product. In addition, the FDA currently requires, unless otherwise informed by the agency, pre-approval of promotional materials for products receiving accelerated approval, which could adversely impact the timing of the commercial launch of the product.

Prior to seeking accelerated approval, we would seek feedback from the FDA, EMA or comparable foreign regulatory authorities and would otherwise evaluate our ability to seek and receive such accelerated approval. However, there can be no assurance that after our evaluation of the feedback and other factors we will decide to pursue or submit a BLA for accelerated approval or any other form of expedited development, review or approval for LX2006 or any other product candidate. Similarly, there can be no assurance that after subsequent feedback from the FDA, EMA or comparable foreign regulatory authorities, we will continue to pursue or apply for accelerated approval or any other form of expedited development, review or approval, even if we initially decide to do so. Furthermore, if we decide to submit an application for accelerated approval, there can be no assurance that such application will be accepted or that any approval will be granted on a timely basis, or at all. The FDA, EMA or other comparable foreign regulatory authorities could also require us to conduct further studies prior to considering our application or granting approval of any type, including, for example, if other products are approved via the accelerated pathway and subsequently converted by FDA to full approval. A failure to obtain accelerated approval or any other form of expedited development, review or approval for our therapeutic candidate would result in a longer time period to commercialization of such therapeutic candidate, could increase the cost of development of such therapeutic candidate and could harm our competitive position in the marketplace.

Priority review designation by the FDA may not lead to a faster regulatory review or approval process and, in any event, does not assure FDA approval of our product candidates.

If the FDA determines that a product candidate is intended to treat a serious disease or condition and, if approved, would provide a significant improvement in the safety or effectiveness of the treatment, prevention, or diagnosis of such disease or condition, the FDA may designate the product candidate for priority review. A priority review designation means that the goal for the FDA to review a marketing application is six months from filing of the application, rather than the standard review period of ten months. We may request priority review for certain of our product candidates. The FDA has broad discretion with respect to whether or not to grant priority review status to a product candidate, so even if we believe a particular product candidate is eligible for such designation or status, the FDA may disagree and decide not to grant it. Moreover, a priority review designation does not necessarily mean a faster regulatory review process or necessarily confer any advantage with respect to approval compared to conventional FDA procedures. Receiving priority review from the FDA does not guarantee approval within the six-month review cycle or thereafter.

We may expend our limited resources to pursue a particular product candidate and fail to capitalize on product candidates that may be more profitable or for which there is a greater likelihood of success.

Because we have limited financial and management resources, we must focus on development programs and product candidates that we identify for specific diseases. As such, currently we are primarily focused on the development of our current pipeline of product candidates. As a result, we may forego or delay pursuit of opportunities with other product candidates. Our resource allocation decisions may cause us to fail to capitalize on viable commercial products or profitable market opportunities. Our spending on current and future development programs and product candidates for specific diseases may not yield any commercially viable products. If we do not accurately evaluate the commercial potential or target market for a particular product candidate, we may relinquish valuable rights to that product candidate through collaboration, licensing or other royalty arrangements in cases in which it would have been more advantageous for us to retain sole development and commercialization rights to such product candidate.

We may not be successful in our efforts to build a pipeline of additional product candidates.

Our business model is centered on developing product candidates targeting patient populations that place significant burden on society and are most amenable to our genetic medicine approach. We are targeting diseases that have seen limited penetration of precision medicine and where we believe there is significant opportunity for gene therapy to play a role as a key therapeutic option. We aim to select, develop and advance product candidates that we believe will have a high probability of technical and regulatory success through development into commercialization. We may not be able to continue to identify and develop new product candidates. Even if we are successful in continuing to build our pipeline, the potential product candidates that we identify may not be suitable for clinical development. For example, they may be shown to have side effects or other characteristics that indicate that they are unlikely to be drugs that will receive marketing approval and achieve market acceptance. If we do not successfully develop and commercialize product candidates based upon our approach, we will not be able to obtain product revenue in future periods, which likely would result in significant harm to our financial position and adversely affect our stock price.

If we are unable to successfully validate, develop and obtain regulatory approval for companion diagnostic tests for our product candidates that require or would commercially benefit from such tests, or experience significant delays in doing so, we may not realize the full commercial potential of these product candidates.

In connection with the clinical development of our product candidates for certain indications, we intend to work with collaborators to develop or obtain access to in vitro companion diagnostic tests to identify patient subsets within a disease category who may derive selective and meaningful benefit from our product candidates. To be successful, we or our collaborators will need to address a number of scientific, technical, regulatory and logistical challenges. The FDA and comparable foreign regulatory authorities regulate in vitro companion diagnostics as medical devices and, under that regulatory framework, will likely require the conduct of clinical trials to demonstrate the safety and effectiveness of any diagnostics we may develop, which we expect will require separate regulatory clearance or approval prior to commercialization. The FDA generally will require approval or clearance of the diagnostic at the same time that the FDA approves the therapeutic product if the FDA determines that safe and effective use of a therapeutic product depends on an in vitro companion diagnostic. The clearance or approval of a companion diagnostic as part of the product label will also limit the use of the product candidate to patients who have met the screening criteria tested for by the companion diagnostic.

We intend to rely on third parties for the design, development and manufacture of companion diagnostic tests for our therapeutic product candidates that may require such tests. If we enter into such collaborative agreements, we will be dependent on the sustained cooperation and effort of our future collaborators in developing and obtaining approval for these companion diagnostics. It may be necessary to resolve issues such as selectivity/specificity, analytical validation, reproducibility, or clinical validation of companion diagnostics during the development and regulatory approval processes. Moreover, even if data from preclinical studies and early clinical trials appear to support development of a companion diagnostic for a product candidate, data generated in later clinical trials may fail to support the analytical and clinical validation of the companion diagnostic. We and our future collaborators may encounter difficulties in developing, obtaining regulatory approval for, manufacturing and commercializing companion diagnostics similar to those we face with respect to our therapeutic candidates themselves, including issues with achieving regulatory clearance or approval, production of sufficient quantities at commercial scale and with appropriate quality standards, and in gaining market acceptance. If we are unable to successfully develop companion diagnostics for these product candidates, or experience delays in doing so, the development of these product candidates may be adversely affected, these product candidates may not obtain marketing approval, and we may not realize the full commercial potential of any of these product candidates that obtain marketing approval. As a result, our business, results of operations and financial condition could be materially harmed. In addition, a diagnostic company with whom we contract may decide to discontinue selling or manufacturing the companion diagnostic test that we anticipate using in connection with development and commercialization of our product candidates or our relationship with such diagnostic company may otherwise terminate. We may not be able to enter into arrangements with another diagnostic company to obtain supplies of an alternative diagnostic test for use in connection with the development and commercialization of our product candidates or do so on commercially reasonable terms, which could adversely affect and/or delay the development or commercialization of our product candidates.

Risks related to the manufacturing of our product candidates

We and our contract manufacturers are subject to significant regulation with respect to manufacturing our products. The third-party manufacturing facilities on which we rely, and any manufacturing facility that we may have in the future, may have limited capacity or fail to meet the applicable stringent regulatory requirements.

We currently have relationships with a limited number of suppliers for the manufacturing of all components of our product candidates. However, if we experience slowdowns or problems with our manufacturing partners and are unable to establish or scale our internal manufacturing capabilities, we will need to continue to contract with manufacturers that can produce the preclinical, clinical and commercial supply of our products. Each supplier may require licenses to manufacture such components if such processes are not owned by the supplier or in the public domain and we may be unable to license such intellectual property rights on reasonable commercial terms or to transfer or sublicense the intellectual property rights we may have with respect to such activities.

All entities involved in the preparation of therapeutics for clinical trials or commercial sale, including our existing contract manufacturers for components of our product candidates, are subject to extensive regulation. Components of a finished therapeutic product approved for commercial sale or used in late-stage clinical trials in the United States and European Union must be manufactured in accordance with cGMP. These regulations govern manufacturing processes and procedures (including recordkeeping) and the implementation and operation of quality systems to control and assure the quality of investigational products and products approved for sale. Poor control of production processes can lead to the introduction of adventitious agents or other contaminants, or to inadvertent changes in the properties or stability of our product candidates that may not be detectable in final product testing. We or our contract manufacturers must supply all necessary documentation in support of a BLA or an MAA on a timely basis. Our potential manufacturing facilities and quality systems and the facilities and quality systems of some or all of our third-party contractors must pass a pre-approval inspection for compliance with the applicable regulations as a condition of regulatory approval of our product candidates or any of our other potential products. In addition, the regulatory authorities may, at any time, audit or inspect a manufacturing facility involved with the preparation of our product candidates or our other potential products or the associated quality systems for compliance with the regulations applicable to the activities being conducted, and they could put a hold on one or more of our clinical trials if the facilities of our contract manufacturing organizations, or CMOs, do not pass such audit or inspections. If these facilities do not pass a pre-approval plant inspection, FDA approval of the products will not be granted.

The regulatory authorities also may, at any time following approval of a product for sale, inspect or audit our manufacturing facilities or those of our third-party contractors. If any such inspection or audit identifies a failure to comply with applicable regulations or if a violation of our product specifications or applicable regulations occurs independent of such an inspection or audit, we or the relevant regulatory authority may require remedial measures that may be costly and/or time-consuming for us or a third party to implement and that may include the temporary or permanent suspension of a clinical trial or commercial sales or the temporary or permanent closure of a facility. Any such remedial measures imposed upon us or third parties with whom we contract could harm our business.

If we or any of our third-party manufacturers fail to maintain regulatory compliance, the FDA can impose regulatory sanctions including, among other things, refusal to approve a pending application for a new drug product or biologic product, or revocation of a pre-existing approval. As a result, our business, financial condition and results of operations may be harmed. Additionally, if supply from one approved manufacturer is interrupted, there could be a significant disruption in commercial supply. An alternative manufacturer would need to be qualified through a BLA and/or an MAA supplement which could result in further delay. The regulatory agencies may also require additional studies if a new manufacturer is relied upon for commercial production. Switching manufacturers may involve substantial costs and is likely to result in a delay in our desired clinical and commercial timelines.

These factors could cause the delay of clinical trials, regulatory submissions, required approvals or commercialization of our product candidates, cause us to incur higher costs and prevent us from commercializing our products successfully, if approved. Furthermore, if our suppliers fail to meet contractual requirements, and we are unable to secure one or more replacement suppliers capable of production at a substantially equivalent cost, our clinical trials may be delayed, or we could lose potential revenue.

Gene therapies are novel, complex and difficult to manufacture. We could experience manufacturing problems that result in delays in the development or commercialization of our product candidates or otherwise harm our business.

The manufacture of gene therapy products is technically complex and necessitates substantial expertise and capital investment. Production difficulties caused by unforeseen events may delay the availability of material for our clinical studies.

We rely on third-party manufacturers to manufacture our product candidates for preclinical studies and clinical trials. The manufacturers of pharmaceutical products must comply with strictly enforced cGMP requirements, state and federal regulations, as well as foreign requirements when applicable. Any failure by us or our CMOs to adhere to or document compliance to such regulatory requirements could lead to a delay or interruption in the availability of our product candidate materials for clinical trials or enforcement action from the FDA, EMA or foreign regulatory authorities. If we or our manufacturers fail to comply with the requirements of the FDA, EMA or other regulatory authority, sanctions could be imposed on us, including clinical holds, fines, injunctions, civil penalties, delays, suspension or withdrawal of approvals, license revocation, seizures or recalls of product candidates or products, operating restrictions and criminal prosecutions, any of which could significantly and adversely affect supplies of our product candidates.

There can be no assurances that our third-party manufacturers will be able to meet our timetable and requirements. If any third party with whom we contract fails to perform its obligations, we may be forced to either manufacture the materials ourselves, for which we may not have the capabilities or resources, or enter into an agreement with a different third-party manufacturer, which we may not be able to do on reasonable terms, if at all. In either scenario, our clinical trials and future commercial supply could be delayed significantly as we establish alternative supply sources. In some cases, the technical skills required to manufacture our product candidates may be unique or proprietary to the original third-party manufacturer and we may have difficulty, or there may be contractual restrictions prohibiting us from, transferring such skills to a back-up or alternate supplier, or we may be unable to transfer such skills at all. In addition, if we are required to change manufacturers for any reason, we will be required to verify that the new manufacturer maintains facilities and procedures that comply with quality standards and with all applicable regulations. We will also need to verify, such as through a manufacturing comparability study, that any new manufacturing process will produce our product candidates according to the specifications previously submitted to the FDA or another regulatory authority. The delays associated with the verification of a new manufacturer could negatively affect our ability to develop product candidates or commercialize our products, if approved, in a timely manner or within budget.

If we are unable to arrange for alternative third-party manufacturing sources on commercially reasonable terms or in a timely manner, we may be delayed in the development of our product candidates. Our dependence upon others for the manufacture of our product candidates may also adversely affect our future profit margins and our ability to commercialize any product candidates that receive regulatory approval on a timely and competitive basis.

Our product candidates require processing steps that are more complex than those required for most chemical pharmaceuticals. Moreover, unlike chemical pharmaceuticals, the physical and chemical properties of a biologic such as our modified virus generally cannot be fully characterized. As a result, assays of the finished product may not be sufficient to ensure that the product will perform in the intended manner. Although we believe that the manufacture of our product candidates may be simplified due to their shared raw materials and other similarities, we cannot be certain that this will be the case and we may be required to develop manufacturing methods that ultimately differ significantly between product candidates, which would require that we invest substantial time and capital to develop suitable manufacturing methods. Our program materials are manufactured using technically complex processes requiring specialized equipment and facilities, highly specific raw materials, cell types and reagents, and other production constraints. Our production process also requires a number of highly specific raw materials, cell types and reagents with limited suppliers. Even though we aim to have backup supplies of raw materials, cell types and reagents whenever possible, we cannot be certain they will be sufficient if our primary sources are unavailable. A shortage of a critical raw material, cell line, or reagent, or a technical issue during manufacturing may lead to delays in clinical development or commercialization plans. We are particularly susceptible to any shortages, delays or our inability to obtain suitable raw materials for our lead product candidates. Any changes in the manufacturing of components of the raw materials we use could result in unanticipated or unfavorable effects in our manufacturing processes, resulting in delays.

In addition, if any of our product candidates obtain approval, the FDA, EMA and other regulatory authorities may require us to submit samples of any lot of any approved product together with the protocols showing the results of applicable tests at any time. Under some circumstances, the FDA, EMA or other regulatory authorities may require that we not distribute a lot until the agency authorizes its release. Slight deviations in the manufacturing process, including those affecting quality attributes and stability, may result in unacceptable changes in the product that could result in lot failures or product recalls. Lot failures or product recalls could cause us to delay product launches or clinical trials, which could be costly to us and otherwise harm our business, financial condition, results of operations and prospects.

We depend on third-party suppliers for materials used in the manufacture of our product candidates, and the loss of these third-party suppliers or their inability to supply us with adequate materials could harm our business.

We rely on third-party suppliers for the materials and components required for the production of our product candidates. Our dependence on these third-party suppliers and the challenges we may face in obtaining adequate supplies of materials involve several risks, including limited control over pricing, availability, and delivery schedules. There is substantial demand and limited supply for certain of the raw materials used to manufacture gene therapy products. As a small company, our negotiation leverage is limited, and we may get lower priority than our competitors that are larger than we are. We cannot be certain that our suppliers will continue to provide us with the quantities of these raw materials within the timelines that we require or satisfy our anticipated specifications and quality requirements. Any supply interruption in limited or sole-sourced raw materials could materially harm our ability to manufacture our product candidates until a new source of supply, if any, could be identified and qualified. We may be unable to find a sufficient alternative supply channel in a reasonable time or on commercially reasonable terms. Any performance failure on the part of our suppliers could delay the development and potential commercialization of our product candidates, including limiting supplies necessary for clinical trials and regulatory approvals, which would have a material adverse effect on our business.

Any contamination or interruption in our manufacturing process, shortages of raw materials or failure of our suppliers of viruses to deliver necessary components could result in delays in our clinical development or marketing schedules.

Given the nature of gene therapy manufacturing, there is a risk of contamination occurring during the manufacturing process. Any contamination could adversely affect our ability to produce product candidates on schedule and could, therefore, harm our results of operations and cause reputational damage. Some of the raw materials required in our manufacturing process are derived from biologic sources. Such raw materials are difficult to procure and may be subject to contamination or recall. A material shortage, contamination, recall or restriction on the use of biologically derived substances in the manufacture of our product candidates could adversely impact or disrupt the commercial manufacturing or the production of clinical material, which could adversely affect our development timelines and our business, financial condition, results of operations and prospects.

Changes in methods of product candidate manufacturing or formulation may result in additional costs or delay.

As product candidates proceed through preclinical studies to late-stage clinical trials towards potential approval and commercialization, it is common that various aspects of the development program, such as manufacturing methods and formulation, are altered along the way in an effort to optimize processes and product characteristics. Such changes carry the risk that they will not achieve our intended objectives. Any such changes could cause our product candidates to perform differently and affect the results of planned clinical trials or other future clinical trials conducted with the materials manufactured using altered processes. Such changes may also require additional testing, FDA notification or FDA approval. This could delay the initiation and completion of clinical trials, require the conduct of bridging clinical trials or the repetition of one or more clinical trials, increase clinical trial costs, delay approval of our product candidates and jeopardize our ability to commence sales and generate revenue. In addition, we may be required to make significant changes to our upstream and downstream processes across our pipeline, which could delay the development of our future product candidates. Regulatory agencies, and in particular the FDA and EMA, have demonstrated increased caution in their regulation of gene therapies, including increased scrutiny related to chemistry, manufacturing and control, or CMC, issues. This increased regulatory scrutiny around gene therapy CMC may result in us being required to conduct additional preclinical studies or clinical trials with respect to any of our product candidates, which may result in delays and increased costs in the development or commercialization of our product candidates and ultimately could lead to the failure to obtain approval for any gene therapy product.

Risks related to the commercialization of our product candidates

Even if any of our product candidates receive marketing approval, they may fail to achieve the degree of market acceptance by physicians, patients, third-party payors and others in the medical community necessary for commercial success.

If any of our product candidates receive marketing approval, they may nonetheless fail to gain sufficient market acceptance by physicians, patients, third-party payors and others in the medical community. If our product candidates do not achieve an adequate level of acceptance, we may not generate significant revenue and we may not become profitable. The degree of market acceptance of our product candidates, if approved for commercial sale, will depend on a number of factors, including:

• their efficacy, safety and potential advantages compared to alternative treatments;
• our ability to offer our products for sale at competitive prices;
• their convenience and ease of administration compared to alternative treatments;
• product labeling or product insert requirements of the FDA or foreign regulatory authorities, including any limitations or warnings contained in a product’s approved labeling, including any boxed warning or REMS;
• the willingness of the target patient population to try new treatments, such as gene therapy as a novel modality for treatment of our target indications and of physicians to prescribe these treatments;
• our ability to hire and retain a sales force in the United States;
• the strength of marketing and distribution support;
• the availability of coverage and adequate reimbursement for our product candidates, once approved, from third-party payors and government authorities;
• the prevalence and severity of any side effects; and
• any restrictions on the use of our products together with other medications.

Negative public opinion of gene therapy and increased regulatory scrutiny of gene therapy and genetic research may adversely impact the development or commercial success of our current and future product candidates.

Our product candidates involve introducing genetic material into a patient’s cells via intrathecal and intravenous administration. The clinical and commercial success of our potential products will depend in part on public acceptance of the use of gene therapy and gene regulation for the prevention or treatment of human diseases. Public attitudes may be influenced by claims that gene therapy and gene regulation are unsafe, unethical or immoral, and consequently, our products may not gain the acceptance of the public or the medical community. Adverse public attitudes may adversely impact our ability to enroll clinical trials. Moreover, our success will depend upon physicians prescribing, and their patients being willing to receive, treatments that involve the use of product candidates we may develop in lieu of, or in addition to, existing treatments with which they are already familiar and for which greater clinical data may be available.

More restrictive government regulations or negative public opinion would have a negative effect on our business or financial condition and may delay or impair the development and commercialization of our product candidates or demand for any products once approved. In recent years, sponsors of other clinical trials involving gene therapies have announced imposition of clinical holds by the FDA to evaluate safety issues arising during the trials. Among the risks in any gene therapy product based on viral vectors are the risks of immunogenicity, elevated liver enzymes and insertional oncogenesis. If any of our vectors demonstrate a similar effect, we may decide or be required to halt or delay further clinical development of any product candidates that utilize that vector. Adverse events in our or others’ clinical trials, even if not ultimately attributable to our product candidates, and the resulting publicity could result in increased governmental regulation, unfavorable public perception, potential regulatory delays in the testing or approval of our product candidates, stricter labeling requirements for those product candidates that are approved and a decrease in demand for any such product candidates. The risk of cancer remains a concern for gene therapy, and we cannot assure that it will not occur in any of our planned or future clinical trials or in any clinical trials conducted by other companies. In addition, there is the potential risk of delayed adverse events following exposure to gene therapy products due to persistent biological activity of the genetic material or other components of products used to carry the genetic material. In addition, for our regulated gene replacement therapy product candidates which require that the expression of a therapeutic transgene be tightly regulated, we may inadvertently cause overexpression, which could lead to numerous issues, including safety and toxicity concerns. Furthermore, one of our regulatory gene replacement therapy candidates, LX1020, requires the insertion of miRNA targets into the viral genome, which is a technology that to our knowledge is not present in any approved gene therapy products. If any such adverse events occur, commercialization of our product candidates or further advancement of our clinical trials could be halted or delayed, which would have a negative impact on our business and operations.

The affected populations for our other product candidates may be smaller than we or third parties currently project, which may affect the addressable markets for our product candidates.

We currently focus our research and product development on several indications that are larger-rare diseases. However, our projections of the number of people who have the diseases we are seeking to treat, as well as the subset of people with these diseases who have the potential to benefit from treatment with our product candidates, are estimates based on our knowledge and understanding of these diseases. These estimates may prove to be incorrect and new studies may further reduce the estimated incidence or prevalence of this disease. The number of patients in the United States, the European Union and elsewhere may turn out to be lower than expected, may not be otherwise amenable to treatment with our product candidate or patients may become increasingly difficult to identify and access, all of which would adversely affect our business, financial condition, results of operations and prospects.

The total addressable market opportunity for our product candidates will ultimately depend upon a number of factors, including the diagnosis and treatment criteria included in the final label, if approved for sale in specified indications, acceptance by the medical community, patient access and product pricing and reimbursement. Incidence and prevalence estimates are frequently based on information and assumptions that are not exact and may not be accurate, and the methodology is forward-looking and potentially speculative. The process we have used in developing an estimated incidence and prevalence range for the indications we are targeting has involved collating limited data from multiple sources. Accordingly, the incidence and prevalence estimates included in this Quarterly Report should be viewed in that context. Further, the data and statistical information used in this Quarterly Report, including estimates derived from them, may differ from information and estimates made by our competitors or from current or future studies conducted by independent sources.

We face significant competition from other biotechnology and pharmaceutical companies, and our operating results will suffer if we fail to compete effectively.

Drug development, particularly in the gene therapy field, is highly competitive and subject to rapid and significant technological advancements. As a significant unmet medical need exists in the cardiovascular disease area, there are several large and small pharmaceutical companies focused on delivering therapeutics for the treatment of these diseases, including those that we are initially targeting. It is likely that additional drugs will become available in the future for the treatment of our target diseases.

We are aware that our competitors are developing product candidates for the treatment of diseases that our product candidates will target. With respect to LX2006, we are aware of a clinical stage gene therapy program in development at Solid Biosciences Inc. and those being developed in collaborations between Voyager Therapeutics, Inc. and Neurocrine Biosciences, Inc. Additionally, we are aware that Prime Medicine, Inc. and Tune Therapeutics, Inc. have early-stage gene editing discovery efforts. Among other treatment modalities for FA, we are aware that Larimar Therapeutics, Inc. is developing a clinical stage product candidate, CTI-1601, that Design Therapeutics, Inc. is developing a product candidate, DT-216P2, and that PTC Therapeutics, Inc. has submitted a new drug application for vatiquinone to the FDA. Reata Pharmaceuticals, Inc.’s omaveloxolone (Skyclarys) was approved by the FDA in 2023, and Biogen Inc. acquired Reata Pharmaceuticals, Inc. for approximately $7.3 billion in the same year and is currently commercializing Skyclarys.

With respect to LX2020, both Rocket and Tenaya Therapeutics Inc. are developing an AAV-based gene therapy candidate designed to deliver a functional PKP2 gene to patients with PKP2-ACM.

Many of our existing or potential competitors have substantially greater financial, technical and human resources than we do and significantly greater experience in the discovery and development of product candidates, as well as in obtaining regulatory approvals of those product candidates in the United States and in foreign countries. Our current and potential future competitors may also have significantly more experience commercializing drugs, particularly gene therapy and other biologics, that have been approved for marketing. Mergers and acquisitions in the pharmaceutical and biotechnology industries could result in even more resources being concentrated among a small number of our competitors.

We will face competition from other drugs or from other non-drug products currently approved or that will be approved in the future in the cardiac and neurology fields, including for the treatment of diseases and diseases in the therapeutic categories we intend to target. Therefore, our ability to compete successfully will depend largely on our ability to:

• develop and commercialize drugs that are advantageous as compared to other products in the market;
• demonstrate through our clinical trials that our product candidates are differentiated from existing and future therapies;
• attract qualified scientific, product development and commercial personnel;
• obtain patent or other proprietary protection for our product candidates;
• obtain required regulatory approvals;
• obtain coverage and adequate reimbursement from, and negotiate competitive pricing with, third-party payors; and
• successfully collaborate with other pharmaceutical companies in the discovery, development and commercialization of new medicines.

The availability of our competitors’ products could limit the demand, and the price we are able to charge, for any product candidate we develop. The inability to compete with existing or subsequently introduced drugs would have an adverse impact on our business, financial condition and prospects. In addition, the reimbursement structure of approved gene therapies by other companies could impact the anticipated reimbursement structure of our gene therapies, if approved, and our business, financial condition, results of operations and prospects.

Established pharmaceutical companies may invest heavily to accelerate discovery and development of novel compounds or to in-license novel compounds that could make our product candidates less competitive. In addition, any new product that competes with an approved product must demonstrate compelling advantages in efficacy, convenience, tolerability and safety in order to overcome price competition and to be commercially successful. Accordingly, our competitors may succeed in obtaining patent protection, discovering, developing, receiving regulatory and marketing approval for, or commercializing, drugs before we do, which would have an adverse impact on our business and results of operations.

Any product candidates for which we intend to seek approval as biologic products may face competition sooner than anticipated.

The Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act, includes a subtitle called the Biologics Price Competition and Innovation Act of 2009, or BPCIA, which created an abbreviated approval pathway for biologics that are biosimilar to or interchangeable with an FDA-licensed reference biological product. Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of its product. The law is complex and is still being interpreted and implemented by the FDA. As a result, its ultimate impact, implementation and meaning are subject to uncertainty. While it is uncertain when such processes intended to implement BPCIA may be fully adopted by the FDA, any such processes could have an adverse effect on the future commercial prospects for our biologics.

There is a risk that any of our product candidates approved as a biological product under a BLA would not qualify for the 12-year period of exclusivity or that this exclusivity could be shortened due to congressional action or otherwise, or that the FDA will not consider our product candidates to be reference products for competing products, potentially creating the opportunity for generic competition sooner than anticipated. Other aspects of the BPCIA, some of which may impact the BPCIA exclusivity provisions, have also been the subject of recent litigation. Moreover, the extent to which a biosimilar, once approved, will be substituted for any one of our reference products in a way that is similar to traditional generic substitution for non-biologics is not yet clear, and will depend on a number of marketplace and regulatory factors that are still developing. If competitors are able to obtain marketing approval for biosimilars referencing our product candidates, if approved, our products may become subject to competition from such biosimilars, with the attendant competitive pressure and potential adverse consequences.

The success of our product candidates will depend significantly on coverage and adequate reimbursement or the willingness of patients, commercial and government payors to pay for these procedures.

We believe our success depends on obtaining and maintaining coverage and adequate reimbursement for our product candidates, including LX2006 and LX2020, and the extent to which patients will be willing to pay out-of-pocket for such products, in the absence of reimbursement for all or part of the cost. In the United States and in other countries, patients who are provided medical treatment for their conditions generally rely on third-party payors to reimburse all or part of the costs associated with their treatment. The availability of coverage and adequacy of reimbursement for our products by third-party payors, including government health care programs (e.g., Medicare, Medicaid, TRICARE), managed care providers, private health insurers, health maintenance organizations and other organizations is essential for most patients to be able to afford medical services and pharmaceutical products such as our product candidates. Third-party payors often rely upon Medicare coverage policy and payment limitations in setting their own coverage and reimbursement policies. However, decisions regarding the extent of coverage and amount of reimbursement to be provided are made on a payor-by-payor basis. One payor’s determination to provide coverage for a drug product does not assure that other payors will also provide coverage, and adequate reimbursement.

The principal decisions about reimbursement for new medicines are typically made by CMS, an agency within the HHS. CMS decides whether and to what extent products will be covered and reimbursed under Medicare and private payors tend to follow CMS to a substantial degree. Most significantly, in August 2022, the Inflation Reduction Act of 2022, or IRA, was signed into law. Among other things, the IRA requires manufacturers of certain drugs to engage in price negotiations with Medicare, with prices that can be negotiated subject to a cap (with resulting prices for the initial ten drugs first effective in 2026); imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); redesigns the Medicare Part D benefit (beginning in 2024); and replaces the Part D coverage gap discount program with a new discounting program (beginning in 2025). The IRA permits the Secretary of the HHS to implement many of these provisions through guidance, as opposed to regulation, for the initial years. On August 29, 2023, HHS announced the list of the first ten drugs that will be subject to price negotiations. HHS has issued and will continue to issue and update guidance implementing the IRA, although the Medicare drug price negotiation program is currently subject to legal challenges. While the impact of the IRA on the pharmaceutical industry cannot yet be fully determined, it is likely to be significant. Only high-expenditure single-source drugs that have been approved for at least 7 years (11 years for single-source biologics) can qualify for negotiation, with the negotiated price taking effect two years after the selection year. For 2026, the first year in which negotiated prices become effective, CMS selected 10 high-cost Medicare Part D drugs in 2023, negotiations began in 2024, and the negotiated maximum fair price for each drug has been announced. CMS has selected 15 additional Medicare Part D drugs for negotiated maximum fair pricing in 2027. For 2028, up to an additional 15 drugs, which may be covered under either Medicare Part B or Part D, will be selected, and for 2029 and subsequent years, up to 20 additional Part B or Part D drugs will be selected. Further, the current administration has issued executive orders focused on decreasing prescription drug prices, including directing the Secretary of HHS to establish a mechanism through which American patients can buy drugs directly from manufacturers who sell at a most-favored-nation price and directing the U.S. Trade Representative and Secretary of Commerce to take action to ensure foreign countries are not engaged in practices that purposefully and unfairly undercut market prices and drive price hikes in the United States. In September and October 2025, the government announced the first two agreements with two major pharmaceutical companies to bring American drug prices in line with the lowest paid by other developed nations, requiring the companies to offer medicines at a deep discount off the list price when selling directly to American patients. Such agreements and other government measures that use most-favored-nation pricing targets for prescription drugs, including the use of international pricing reference to set drug prices in the United States, or increases generic and biosimilar drug entry sooner than expected, can have a material adverse effect on our industry, ability to set adequate pricing for new drugs to recover research and development costs, ability to attract potential investors and potential buyers in the future. We cannot predict the full impact of the executive orders focused on reducing prescription drug prices or increasing domestic drug manufacturing capacity, or other measures that may be implemented by the current administration related to drug pricing, drug supply chain and manufacturing in the United States. Such cost containment policies and executive orders could substantially and negatively impact the prices we may charge for any approved products, which could harm our valuation, ability to generate revenue and achieve and sustain profitability. In addition, the One Big Beautiful Bill Act, or OBBBA, which was signed into law in July 2025, includes provisions that will impact the United States healthcare system in various ways, including by cuts to Medicaid and introducing new participant work and eligibility requirements for Medicaid coverage, which are expected to significantly change the administration and applicability of Medicaid coverage. Although the full impact of the OBBBA on the healthcare system and our business is uncertain, the resulting changes may increase the cost and complexity of completing clinical development of and launching any product candidates for which we may receive regulatory approval, which could adversely affect our business and prospects.

Third-party payors determine which products and procedures they will cover and establish reimbursement levels. Even if a third-party payor covers a particular product or procedure, the resulting reimbursement payment rates may not be adequate. Patients who are treated in-office for a medical condition generally rely on third-party payors to reimburse all or part of the costs associated with the procedure, including costs associated with products used during the procedure, and may be unwilling to undergo such procedures in the absence of such coverage and adequate reimbursement. Physicians may be unlikely to offer procedures for such treatment if they are not covered by insurance and may be unlikely to purchase and use our product candidates, if approved, for our stated diseases unless coverage is provided and reimbursement is adequate. In addition, for products administered under the supervision of a physician, obtaining coverage and adequate reimbursement may be particularly difficult because of the higher prices often associated with such drugs. Further, coverage policies and third-party reimbursement rates may change at any time. Therefore, even if favorable coverage and reimbursement status is attained, less favorable coverage policies and reimbursement rates may be implemented in the future. In addition, companion diagnostic tests require coverage and reimbursement separate and apart from the coverage and reimbursement for their companion pharmaceutical or biological products. Similar challenges to obtaining coverage and reimbursement, applicable to pharmaceutical or biological products, will apply to companion diagnostics.

Reimbursement by a third-party payor may depend upon a number of factors, including the third-party payor’s determination that a procedure is a covered benefit under its health plan; safe, effective and medically necessary; appropriate for the specific patient; cost-effective; supported by peer-reviewed medical journals; included in clinical practice guidelines; and neither cosmetic, experimental, nor investigational. Further, increasing efforts by third-party payors in the United States and abroad to cap or reduce healthcare costs may cause such organizations to limit both coverage and the level of reimbursement for newly approved products and, as a result, they may not cover or provide adequate payment for our product candidates. In order to secure coverage and reimbursement for any product that might be approved for sale, we may need to conduct expensive pharmacoeconomic studies in order to demonstrate the medical necessity and cost-effectiveness of our products, in addition to the costs required to obtain FDA or comparable regulatory approvals. Additionally, we may also need to provide discounts to purchasers, private health plans or government healthcare programs. Our product candidates may nonetheless not be considered medically necessary or cost-effective. If third-party payors do not consider a product to be cost-effective compared to other available therapies, they may not cover the product after approval as a benefit under their plans or, if they do, the level of payment may not be sufficient to allow a company to sell its products at a profit. We expect to experience pricing pressures from third-party payors in connection with the potential sale of any of our product candidates.

Foreign governments also have their own healthcare reimbursement systems, which vary significantly by country and region, and we cannot be sure that coverage and adequate reimbursement will be made available with respect to the treatments in which our products are used under any foreign reimbursement system.

There can be no assurance that LX2006, LX2020 or any other product candidates, if approved for sale in the United States or in other countries, will be considered medically reasonable and necessary, that it will be considered cost-effective by third-party payors, that coverage or an adequate level of reimbursement will be available or that reimbursement policies and practices in the United States and in foreign countries where our products are sold will not adversely affect our ability to sell our product candidates profitably, if they are approved for sale.

Product liability lawsuits against us could cause us to incur substantial liabilities and to limit commercialization of any products that we may develop.

We face an inherent risk of product liability exposure related to the testing of our product candidates in human clinical trials and will face an even greater risk if we commercially sell any products that we may develop. If we cannot successfully defend ourselves against claims that our product candidates or drugs caused injuries, we will incur substantial liabilities. Regardless of merit or eventual outcome, liability claims may result in:

• decreased demand for any product candidates or drugs that we may develop;
• injury to our reputation and significant negative media attention;
• withdrawal of clinical trial participants;
• significant costs to defend the related litigation;
• substantial monetary awards paid to trial participants or patients;
• loss of revenue;
• reduced resources of our management to pursue our business strategy; and
• the inability to commercialize any products that we may develop.

Although we maintain product liability insurance coverage, such insurance may not be adequate to cover all liabilities that we may incur. We may need to increase our insurance coverage as we expand our clinical trials or if we commence commercialization of our product candidates. Insurance coverage is increasingly expensive. We may not be able to maintain insurance coverage at a reasonable cost or in an amount adequate to satisfy any liability that may arise.

Risks related to our dependence on third parties

Currently, we rely on our collaborations with Cornell University and The Regents of UCSD to conduct research and development for many of our pipeline programs, including conducting preclinical and IND-enabling studies for portions of our near-term future pipeline. Failure or delay of Cornell University or The Regents of UCSD to fulfill all or part of their respective obligations to us under our agreements, a breakdown in collaboration between the parties or a complete or partial loss of either of these relationships could materially harm our business.

Our collaboration with Cornell University is critical to our business and in May 2020, we entered into two separate license agreements with Cornell University pursuant to which we obtained rights under certain patents, know-how and data to exploit products and technologies covered by such intellectual property. As part of our first license agreement, as amended, we assumed oversight for the conduct of the Phase 1/2 clinical trial of LX1001 that was initiated by Cornell University at the end of 2019. As part of our second license agreement with Cornell University, as amended, we obtained certain rights to portfolios for infantile neuronal ceroid lipofuscinosis type 2 (also called CLN2 Batten disease) and FA cardiomyopathy, as well as an assignment of Cornell University’s IND to support the development of our LX1004 program. We entered into a third license agreement with Cornell University, or Third Cornell License Agreement, in April 2024 pursuant to which we obtained certain rights for FA cardiomyopathy, including rights to current and future clinical data from an ongoing Cornell University investigator-initiated Phase 1A trial of a gene therapy candidate AAVrh10.hFXN, known as LX2006 at Lexeo. Pursuant to our license agreements with Cornell University, we are obligated to diligently proceed with the development, manufacture, and sale of licensed products. If Cornell University delays or fails to perform its obligations under the license agreements terminates any of the license agreements in accordance with its terms, or a dispute otherwise arises between the parties concerning the terms of the agreements or our respective rights to licensed technology, our pipeline of product candidates would be significantly adversely affected and our prospects may be materially harmed.

Our collaboration with UCSD is also highly important to our business, as we have licensed from UCSD intellectual property rights related to our LX2020, LX2021 and LX2022 programs under three separate license agreements, and we have entered into sponsored research agreements with UCSD for preclinical research and development for these programs. If The Regents of UCSD delays or fails to perform its obligations under either of the sponsored research agreements or any of the license agreements, disagrees with our interpretation of the terms of the sponsored research agreements, license agreements or our discovery plans, or terminates any of our existing license agreements, our pipeline of product candidates would be significantly adversely affected and our prospects may be materially harmed.

We intend to continue to rely on third parties to conduct a significant portion of our existing clinical trials and potential future clinical trials for product candidates, and those third parties may not perform satisfactorily, including failing to meet deadlines for the completion of such trials.

We engage CROs to help conduct our ongoing clinical trials. We expect to continue to rely on third parties, including clinical data management organizations, medical institutions and clinical investigators, to conduct those clinical trials and any future clinical trials. Any of these third parties may terminate their engagements with us, some in the event of an uncured material breach and some at any time for convenience. If any of our relationships with these third parties terminate, we may not be able to timely enter into arrangements with alternative third parties or to do so on commercially reasonable terms, if at all. Switching or adding a CRO involves substantial cost and requires management time and focus. In addition, there is a natural transition period when a new CRO commences work. As a result, delays occur, which can materially impact our ability to meet our desired clinical development timelines. Though we intend to carefully manage our relationships with our CROs, there can be no assurance that we will not encounter challenges or delays in the future or that these delays or challenges will not have a material adverse impact on our business, financial condition and prospects.

In addition, any third parties conducting our clinical trials will not be our employees, and except for remedies available to us under our agreements with such third parties, we cannot control whether or not they devote sufficient time and resources to our clinical programs. If these third parties do not successfully carry out their contractual duties or obligations or meet expected deadlines, if they need to be replaced or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to our clinical protocols, regulatory requirements or for other reasons, our clinical trials may be extended, delayed or terminated and we may not be able to obtain regulatory approval for or successfully commercialize our product candidates. Consequently, our results of operations and the commercial prospects for our product candidates would be harmed, our costs could increase substantially and our ability to generate revenue could be delayed significantly.

We rely on these parties for execution of our preclinical studies and clinical trials, and generally do not control their activities. Our reliance on these third parties for research and development activities will reduce our control over these activities but will not relieve us of our responsibilities. For example, we will remain responsible for ensuring that each of our clinical trials is conducted in accordance with the general investigational plan and protocols for the trial. Moreover, the FDA requires us to comply with cGCP regulations, for conducting, recording and reporting the results of clinical trials to assure that data and reported results are credible and accurate and that the rights, integrity and confidentiality of trial participants are protected. We also are required to register ongoing clinical trials and post the results of completed clinical trials on a government-sponsored database, www.clinicaltrials.gov, within specified time frames. Failure to do so can result in fines, adverse publicity and civil and criminal sanctions. If we or any of our CROs or other third parties, including trial sites, fail to comply with applicable cGCPs, or experience material protocol deviations, the clinical data generated in our clinical trials may be deemed unreliable and the FDA, EMA or comparable foreign regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. If the FDA or any regulatory authority determines that our clinical data are not reliable for any reason, or if we encounter any data integrity issues, the FDA or other regulatory authorities may require us to exclude such data, which may cause the trial to be underpowered and fail to meet the trial endpoints. We cannot assure you that upon inspection by a given regulatory authority, such regulatory authority will determine that any of our clinical trials complies with cGCP regulations. In addition, our clinical trials must be conducted with product produced under cGMP conditions. Our failure to comply with these regulations may require us to repeat clinical trials, which would delay the regulatory approval process.

In addition, principal investigators for our clinical trials may serve as scientific advisors or consultants to us from time to time and receive compensation in connection with such services. Under certain circumstances, we may be required to report some of these relationships to the FDA. The FDA may conclude that a financial relationship between us and a principal investigator has created a conflict of interest or otherwise affected interpretation of the trial. The FDA may therefore question the integrity of the data generated at the applicable clinical trial site and the utility of the clinical trial itself may be jeopardized. This could result in a delay in approval, or rejection, of our marketing applications by the FDA and may ultimately lead to the denial of marketing approval of LX2006, LX2020 or any other product candidates.

We also expect to rely on other third parties to store and distribute product supplies for our clinical trials. Any performance failure on the part of our distributors could delay clinical development or marketing approval of our product candidates or commercialization of our products, producing additional losses and depriving us of potential revenue.

We may seek collaborations with non-academic third parties for the development or commercialization of our product candidates. If those collaborations are not successful, we may not be able to capitalize on the market potential of these product candidates.

We may seek third-party collaborators for the development and commercialization of our product candidates, including for the commercialization of any of our product candidates that are approved for marketing outside the United States. Our likely collaborators for any such arrangements include regional and national pharmaceutical companies and biotechnology companies. If we enter into any additional such arrangements with any third parties, we will likely have limited control over the amount and timing of resources that our collaborators dedicate to the development or commercialization of our product candidates. Our ability to generate revenue from these arrangements will depend on our collaborators’ abilities to successfully perform the functions assigned to them in these arrangements. Collaborations involving our product candidates pose the following risks to us:

• collaborators have significant discretion in determining the efforts and resources that they will apply to these collaborations;

• collaborators may not perform their obligations as expected;

• collaborators may not pursue development and commercialization of any product candidates that achieve regulatory approval or may elect not to continue or renew development or commercialization programs based on clinical trial results, changes in the collaborators’ strategic focus or available funding, or external factors, such as an acquisition, that divert resources or create competing priorities;

• collaborators may delay clinical trials, provide insufficient funding for a clinical trial program, stop a clinical trial or abandon a product candidate, repeat or conduct new clinical trials or require a new formulation of a product candidate for clinical testing;

• collaborators could independently develop, or develop with third parties, products that compete directly or indirectly with our product candidates if the collaborators believe that competitive products are more likely to be successfully developed or can be commercialized under terms that are more economically attractive than ours;

• we could grant exclusive rights to our collaborators that would prevent us from collaborating with others;

• product candidates discovered in collaboration with us may be viewed by our collaborators as competitive with their own product candidates or drugs, which may cause collaborators to cease to devote resources to the commercialization of our product candidates;

• a collaborator with marketing and distribution rights to one or more of our product candidates that achieve regulatory approval may not commit sufficient resources to the marketing and distribution of such products;

• disagreements with collaborators, including disagreements over proprietary rights, contract interpretation or the preferred course of development, might cause delays or termination of the research, development or commercialization of product candidates, might lead to additional responsibilities for us with respect to product candidates, or might result in litigation or arbitration, any of which would be time-consuming and expensive;

• collaborators may not properly maintain or defend our or their intellectual property rights or may use our or their proprietary information in such a way as to invite litigation that could jeopardize or invalidate such intellectual property or proprietary information or expose us to potential litigation;

• collaborators may infringe the intellectual property rights of third parties, which may expose us to litigation and potential liability; and

• collaborations may be terminated for the convenience of the collaborator and, if terminated, we could be required to raise additional capital to pursue further development or commercialization of the applicable product candidates.

Collaboration agreements may not lead to development or commercialization of product candidates in the most efficient manner or at all. If any future collaborator of ours were to be involved in a business combination, the continued pursuit and emphasis on our product development or commercialization program could be delayed, diminished or terminated.

We face significant competition in seeking appropriate collaborators. Whether we reach a definitive agreement for any collaboration will depend, among other things, upon our assessment of the collaborator’s resources and expertise, the terms and conditions of the proposed collaboration and the proposed collaborator’s evaluation of a number of factors. Those factors may include the design or results of clinical trials, the likelihood of approval by the FDA or similar regulatory authorities outside the United States, the potential market for the subject product candidate, the costs and complexities of manufacturing and delivering such product candidate to patients, the potential of competing products, the existence of uncertainty with respect to our ownership of technology, which can exist if there is a challenge to such ownership without regard to the merits of the challenge and industry and market conditions generally. The collaborator may also consider alternative product candidates or technologies for similar diseases that may be available to collaborate on and whether such a collaboration could be more attractive than the one with us for our product candidate. Collaborations are complex and time-consuming to negotiate and document. In addition, there have been a significant number of recent business combinations among large pharmaceutical companies that have resulted in a reduced number of potential future collaborators.

We may not be able to negotiate additional collaborations on a timely basis, on acceptable terms, or at all. If we are unable to do so, we may have to curtail the development of such product candidate, reduce or delay its development program or one or more of our other development programs, delay its potential commercialization or reduce the scope of any sales or marketing activities, or increase our expenditures and undertake development or commercialization activities at our own expense. If we elect to increase our expenditures to fund development or commercialization activities on our own, we may need to obtain additional capital, which may not be available to us on acceptable terms or at all. If we do not have sufficient funds, we may not be able to further develop our product candidates or bring them to market and generate revenue.

Risks related to intellectual property

If we are unable to obtain or protect intellectual property rights related to any of our product candidates, we may not be able to compete effectively in our market.

We rely upon a combination of patents, trade secret protection and confidentiality agreements to protect the intellectual property related to our product candidates, including LX2006, LX2020, LX2021, LX2022, LX1001, LX1020, LX1021, and other programs, their respective components, formulations, therapies, methods used to manufacture them and methods of treatment.

Our success depends in large part on our ability to obtain and maintain patent and other intellectual property protection in the United States and in other countries with respect to our proprietary technology and product candidates.

We cannot offer any assurances about which of our patent applications will issue, the breadth of any resulting patent or whether any of the issued patents will be found invalid and unenforceable or will be threatened by third parties. We cannot offer any assurances that the breadth of our granted patents will be sufficient to stop a competitor from developing and commercializing a product, including a biosimilar product that would be competitive with one or more of our product candidates. Furthermore, any successful challenge to these patents or any other patents owned by or licensed to us after patent issuance could deprive us of rights necessary for the successful commercialization of any of our product candidates. Further, if we encounter delays in regulatory approvals, the period of time during which we could market a product candidate under patent protection could be reduced.

The patent prosecution process is expensive and time-consuming. We may not be able to prepare, file and prosecute all necessary or desirable patent applications at a commercially reasonable cost or in a timely manner or in all jurisdictions. It is also possible that we may fail to identify patentable aspects of inventions made in the course of development and commercialization activities before it is too late to obtain patent protection on them. We may not be able to obtain or maintain patent applications and patents due to the subject matter claimed in such patent applications and patents being in the public domain. In some cases, the work of certain academic researchers in the gene therapy field has entered the public domain, which may preclude our ability to obtain patent protection for certain inventions relating to such work. Although we enter into nondisclosure and confidentiality agreements with parties who have access to confidential or patentable aspects of our research and development output, such as our employees, corporate collaborators, outside scientific collaborators, contract manufacturers, consultants, advisors and other third parties, any of these parties may breach these agreements and disclose such output before a patent application is filed, thereby jeopardizing our ability to seek patent protection. Consequently, we would not be able to prevent any third party from using any technology that is in the public domain to compete with our product candidates. In addition, as the licensee of patents from Cornell University and UCSD, we have less control over the prosecution and enforcement of those patents than we would if we owned the patents. While we do have typical rights with respect to those patents under university license agreements, our ability to enforce those patents to maintain exclusivity in our markets may be limited by the terms of our agreements with Cornell University and UCSD. In addition, to the extent the federal government provided research funding to the licensor university for any technology licensed under the license agreements, then if the federal government elects to exercise any of its overriding rights which may apply as a result of provision of such funding, we may be subject to changes in market exclusivity or other material business requirements or constraints. Moreover, depending on the terms of any future in-licenses to which we may become a party, we may not have the right to control the preparation, filing and prosecution of patent applications, or to maintain the patents, covering technology in-licensed from third parties. Therefore, these patents and patent applications may not be prosecuted and enforced in a manner consistent with the best interests of our business.

The patent position of biotechnology and pharmaceutical companies generally is highly uncertain, involves complex legal and factual questions and has, in recent years, been the subject of much litigation. As a result, the issuance, scope, validity, enforceability and commercial value of any patent rights are highly uncertain. Our owned and licensed pending and future patent applications may not result in issued patents which protect our technology or product candidates, effectively prevent others from commercializing competitive technologies and product candidates or otherwise provide any competitive advantage. In fact, patent applications may not issue as patents at all. Even if patent applications we license or own currently or in the future issue as patents, they may not issue in a form that will provide us with any meaningful protection, prevent competitors or other third parties from competing with us, or otherwise provide us with any competitive advantage. Any patents that we hold or in-license may be challenged, narrowed, circumvented, or invalidated by third parties. Consequently, we do not know whether any of our technologies and product candidates will be protectable or remain protected by valid and enforceable patents. In addition, our existing patents and any future patents we obtain may not be sufficiently broad to prevent others from using our technology or from developing competing technologies and products, and the coverage claimed in a patent application can be significantly reduced before the patent is issued, and its scope can be reinterpreted after issuance. Any failure to obtain, maintain or defend our patents and other intellectual property could have a material adverse effect on our business, financial conditions, results of operations and prospects.

We cannot be certain that we are the first to invent the inventions covered by pending patent applications and, if we are not, we may be subject to priority or entitlement disputes. We may be required to disclaim part or all of the term of certain patents or all of the term of certain patent applications. There may be prior art of which we are not aware that may affect the validity or enforceability of a patent claim. There also may be prior art of which we are aware, but which we do not believe affects the validity or enforceability of a claim, which may, nonetheless, ultimately be found to affect the validity or enforceability of a claim. Since patent applications in the United States and other countries are confidential for a period of time after filing, at any moment in time, we cannot be certain that we were in the past or will be in the future the first to file any patent application related to our product candidates. For example, some patent applications in the United States may be maintained in secrecy until the patents are issued. Further, publications in the scientific literature often lag behind actual discoveries. Consequently, we cannot be certain that others have not filed patent applications for technology covered by our owned and in-licensed issued patents or our pending applications, or that we or, if applicable, a licensor, were the first to invent or first to file an application for the technology.

It is possible that defects of form in the preparation or filing of our patents or patent applications may exist, or may arise in the future, for example, with respect to proper priority claims, inventorship, claim scope, or requests for patent term adjustments. If there are material defects in the form, preparation, prosecution, or enforcement of our patents or patent applications, such patents may be invalid and/or unenforceable, and such applications may never result in valid, enforceable patents. Any of these outcomes could impair our ability to prevent competition from third parties, which may have an adverse impact on our business.

In addition to the protection provided by our patent estate, we rely on trade secret protection and confidentiality agreements to protect proprietary know-how that is not amenable to patent protection. Although we generally require all of our employees to assign their inventions to us, and all of our employees, consultants, advisors and any third parties who have access to our proprietary know-how, information, or technology to enter into confidentiality agreements, we cannot provide any assurances that all such agreements have been duly executed, or that our trade secrets and other confidential proprietary information will not be disclosed. In addition, while we have undertaken reasonable efforts to ensure such agreements are enforceable and that employees and third parties comply with their obligations thereunder, these agreements may be found insufficient by a court of law or may be breached, or we may not enter into sufficient agreements with such individuals in the first instance, in either case potentially resulting in the unauthorized use or disclosure of our trade secrets and other intellectual property, including to our competitors, which could cause us to lose any competitive advantage resulting from this intellectual property. Individuals not subject to invention assignment agreements may make adverse ownership claims to our current and future intellectual property. Moreover, our competitors may independently develop knowledge, methods and know-how equivalent to our trade secrets. Competitors could purchase our products, if approved, and replicate some or all of the competitive advantages we derive from our development efforts for technologies on which we do not have patent protection. If any of our trade secrets were to be lawfully obtained or independently developed by a competitor, we would have no right to prevent them, or those to whom they communicate it, from using that technology or information to compete with us. If any of our trade secrets were to be disclosed to or independently developed by a competitor, our competitive position would be harmed.

Enforcing a claim that a third-party entity illegally obtained and is using any of our trade secrets is expensive and time-consuming, and the outcome is unpredictable, and we may not be able to obtain adequate remedies for such breaches.

We also seek to preserve the integrity and confidentiality of our data and trade secrets by working to maintain the physical security of our premises and physical and electronic security of our information technology systems. Our confidentiality agreements may, however, be breached, and we may not have adequate remedies for any breach. Our and other applicable security measures may also not be able to prevent security breaches and other compromises of the security of our trade secrets or other data. Also, if the steps taken to maintain our trade secrets are deemed inadequate, we may have insufficient recourse against third parties for misappropriating the trade secret. In addition, others may independently discover our trade secrets and proprietary information. For example, the FDA is considering whether to make additional information publicly available on a routine basis, including information that we may consider to be trade secrets or other proprietary information, and it is not clear at the present time how the FDA’s disclosure policies may change in the future. If we are unable to prevent material disclosure of the non-patented intellectual property related to our technologies to third parties, and there is no guarantee that we will have any such enforceable trade secret protection, we may not be able to establish or maintain a competitive advantage in our market, which could materially adversely affect our business, results of operations and financial condition.

Patent terms may be inadequate to protect our competitive position on our products for an adequate amount of time, and if we do not obtain protection under the Hatch-Waxman Amendments and similar non-United States legislation for extending the term of patents covering each of our product candidates, our business may be materially harmed.

Given the amount of time required for the development, testing and regulatory review of new product candidates, patents protecting such candidates might expire before or shortly after such product candidates are commercialized. Depending upon the timing, duration and conditions of FDA marketing approval of our product candidates, one or more of our United States patents may be eligible for limited patent term extension under the Drug Price Competition and Patent Term Restoration Act of 1984, referred to as the Hatch-Waxman Amendments, and similar legislation in the European Union. The Hatch-Waxman Amendments permit a patent term extension of up to five years for a patent covering an approved product as compensation for effective patent term lost during product development and the FDA regulatory review process. A patent term extension cannot extend the remaining term of a patent beyond a total of 14 years from the date of product approval. Only one patent may be extended, and only those claims covering the approved drug, a method for using it, or a method for manufacturing it may be extended. However, we may not receive an extension if we fail to apply within applicable deadlines, fail to apply prior to expiration of relevant patents or otherwise fail to satisfy applicable requirements. Moreover, the length of the extension could be less than we request. If we are unable to obtain patent term extension or the term of any such extension is less than we request, the period during which we can enforce our patent rights for that product will be shortened and our competitors may obtain approval to market competing products sooner. As a result, our revenue from applicable products could be reduced and could have a material adverse effect on our business.

We in-license key intellectual property necessary for the development of each of our current product candidates. If we fail to comply with our obligations in our current and future intellectual property licenses with third parties, resulting in the termination of such licenses, we could lose rights that are important to our business.

We are heavily reliant upon licenses to certain patent rights and proprietary technology for the development of each of our current product candidates. In particular, we in-license key patents and patent applications from Adverum related to LX2006, we in-license patent applications and know-how from Cornell University related to our LX2006, LX1001, LX1020 and LX1021 product candidates, and we in-license patent applications and know-how from UCSD related to our LX2020, LX2021 and LX2022 product candidates. Our license agreements impose diligence and milestone and royalty payment obligations on us, and also contain certain development requirements. If we fail to comply with our obligations, our licensors may have the right to terminate our licenses, in which event we will not be able to develop, manufacture or market any product using the intellectual property under any such terminated agreement and may face other penalties. Such an occurrence would materially adversely affect our business prospects.

Certain of our licenses may not provide us with exclusive rights to use the licensed intellectual property and technology, or may not provide us with exclusive rights to use such intellectual property and technology in all relevant fields of use and in all territories in which we may wish to develop or commercialize our technology and product candidates in the future. In addition, the intellectual property rights licensed to us by our licensors, including certain intellectual property licensed by Cornell University UCSD, and Adverum, at least in some respects, may be used by such licensors or licensed to third parties, and such third parties may have certain enforcement rights with respect to such intellectual property. Thus, patents licensed to us could be put at risk of being invalidated or interpreted narrowly in litigation filed by or against our licensors or another licensee or in administrative proceedings brought by or against our licensors or another licensee in response to such litigation or for other reasons. As a result, we may not be able to prevent competitors or other third parties from developing and commercializing competitive products, including in territories covered by our licenses.

Licenses to additional third-party technology and materials that may be required for our development programs may not be available in the future or may not be available on commercially reasonable terms, or at all, which could have a material adverse effect on our business and financial condition. In such events, we may be required to expend significant time and resources to redesign our technology, product candidates, or the methods for manufacturing them or to develop or license replacement technology, all of which may not be feasible on a technical or commercial basis. If we are unable to do so, we may be unable to develop or commercialize the affected technology or product candidates. Even if we are able to obtain such additional licenses, they may be non-exclusive thereby giving our competitors and other third parties access to the same technology licensed to us.

If we or our licensors fail to adequately protect our licensed intellectual property, our ability to commercialize our product candidates and technology could suffer. Although we have oversight rights, Cornell University and UCSD generally control the prosecution, maintenance and enforcement of our in-licensed patents and patent applications. Therefore, we cannot be certain that the prosecution, maintenance and enforcement of these patent rights will be in a manner consistent with the best interests of our business, or in compliance with applicable laws and regulations, or will result in valid and enforceable patents and other intellectual property rights. It is possible that our licensors’ infringement proceedings or defense activities may be less vigorous than had we conducted them ourselves or may not be conducted in accordance with our best interests. If we or our licensors fail to maintain such patents or patent applications, or if we or our licensor lose rights to those patents or patent applications, the rights we have licensed may be reduced or eliminated and our right to develop and commercialize any of our product candidates that are the subject of such licensed rights could be adversely affected. In addition to the foregoing, the risks associated with patent rights that we license from third parties will also apply to patent rights we may own in the future.

Further, if we fail to comply with our development obligations under our license agreements, we may lose our patent rights with respect to such agreement on a territory-by-territory basis, which would affect our patent rights worldwide. In spite of our efforts, our current and future licensors might conclude that we have materially breached our obligations under our license agreements and might therefore terminate such license agreements, thereby removing or limiting our ability to develop and commercialize products and technology covered by these license agreements. Disputes may also arise between us and our licensors regarding intellectual property subject to a license agreement, including:

• the scope of rights granted under the license agreement and other interpretation-related issues;
• our financial and other obligations under the license agreement;
• whether and the extent to which our technology and processes infringe on intellectual property of the licensor that is not subject to the licensing agreement;
• our right to sublicense patent and other rights to third parties under collaborative development relationships;
• our diligence obligations with respect to the use of the licensed technology in relation to our development and commercialization of our product candidates and what activities satisfy those diligence obligations;
• the inventorship or ownership of inventions and know-how resulting from the joint creation or use of intellectual property by our licensors and us and our partners; and
• the priority of invention of patented technology.

If disputes over intellectual property that we have licensed prevent or impair our ability to maintain our current licensing arrangements on acceptable terms, we may be unable to successfully develop and commercialize the affected technology or product candidates. In addition, if any such disputes result in the termination of our intellectual property licenses, this could result in the loss of our ability to develop and commercialize our lead product candidates, or we could lose other significant rights, experience significant delays in the development and commercialization of our other product candidates, or incur liability for damages, any of which could have a material adverse effect on our business, financial condition, results of operations and prospects. In addition, we may seek to obtain additional licenses from our licensors and, in connection with obtaining such licenses, we may agree to amend our existing licenses in a manner that may be more favorable to the licensors, including by agreeing to terms that could enable third parties, including our competitors, to receive licenses to a portion of the intellectual property that is subject to our existing licenses and to compete with our product candidates.

Some of our future agreements with certain of our third-party research partners may provide that improvements developed in the course of our relationship may be owned solely by either us or our third-party research partner. If we determine that rights to such improvements owned solely by a third-party research partner or other third party with whom we collaborate are necessary to commercialize our therapeutic product candidates or maintain our competitive advantage, we may need to obtain a license from such third party in order to use the improvements and continue developing, manufacturing or marketing our drug candidates. We may not be able to obtain such a license on an exclusive basis, on commercially reasonable terms, or at all, which could prevent us from commercializing our product candidates or allow our competitors or others the chance to access technology that is important to our business.

Termination of our current or any future license agreements would reduce or eliminate our rights under these agreements and may result in our having to negotiate new or reinstated agreements with less favorable terms or cause us to lose our rights under these agreements, including our rights to important intellectual property or technology. Any of the foregoing could prevent us from commercializing our other product candidates, which could have a material adverse effect on our operating results and overall financial condition.

In addition, intellectual property rights that we in-license in the future may be sublicenses under intellectual property owned by third parties, in some cases through multiple tiers. The actions of our licensors may therefore affect our rights to use our sublicensed intellectual property, even if we are in compliance with all of the obligations under our license agreements. Should our licensors or any of the upstream licensors fail to comply with their obligations under the agreements pursuant to which they obtain the rights that are sublicensed to us, or should such agreements be terminated or amended, our ability to develop and commercialize our product candidates may be materially harmed.

In addition, a third party may in the future bring claims that our performance under our license agreements, including our sponsoring of clinical trials, interferes with such third party’s rights under its agreement with one of our licensors. If any such claim were successful, it may adversely affect our rights and ability to advance our product candidates as clinical candidates or subject us to liability for monetary damages, any of which would have an adverse effect on our business, financial condition, results of operations and prospects.

We are generally also subject to all of the same risks with respect to protection of intellectual property that we license as we are for intellectual property that we own, which are described above and below. If we or our licensors fail to adequately protect this intellectual property, our ability to commercialize products could suffer. We may not be successful in obtaining or maintaining necessary rights to product components and processes for our development pipeline through acquisitions and in-licenses.

Presently, we have obtained rights to certain intellectual property rights through licenses from third parties to develop, manufacture and commercialize our lead product candidates and other potential product candidates in our pipeline. Because the commercialization of our product candidates may require the use of additional intellectual property rights held by third parties, the growth of our business likely will depend, in part, on our ability to acquire or license these intellectual property rights. Our product candidates also require specific formulations and manufacturing processes to work effectively and efficiently, and some of these rights are held by others.

We may be unable to acquire or in-license any compositions, methods of use, processes or other third-party intellectual property rights from third parties that we identify as necessary, important or more expedient to further our business operations. In addition, even if we are able to obtain such licenses, we may fail to obtain any of these licenses at a reasonable cost or on reasonable terms, which would harm our business. Were that to happen, we may need to cease use of the product candidates and technologies covered by those third-party intellectual property rights and may need to seek to develop alternative approaches that do not infringe, misappropriate or violate those intellectual property rights, which may entail additional costs and development delays if we are able to develop such alternatives, or which may not be feasible. Even if we are able to obtain a license, it may be non-exclusive, which means that our competitors may also receive access to the same technologies licensed to us. The licensing and acquisition of third-party intellectual property rights is a competitive practice, and companies that may be more established, or have greater resources than we do, may also be pursuing strategies to license or acquire third-party intellectual property rights that we may consider necessary or attractive in order to commercialize our product candidates. More established companies may have a competitive advantage over us due to their larger size and cash resources or greater clinical development and commercialization capabilities. In addition, companies that perceive us to be a competitor may be unwilling to assign or license rights to us. There can be no assurance that we will be able to successfully complete such negotiations and ultimately acquire the rights to the intellectual property surrounding the additional product candidates that we may seek to acquire. We also may be unable to license or acquire third-party intellectual property rights on terms that would allow us to make an appropriate return on our investment.

If we are unable to successfully obtain rights to required third-party intellectual property or maintain the existing intellectual property rights we have licensed, we may be required to expend significant time and resources to redesign our product candidates, or to develop or license replacement technology, all of which may not be feasible on a technical or commercial basis, and we may have to abandon development of our product candidates, any of which could have a material adverse effect on our business, financial condition, results of operations and prospects.

Our intellectual property licenses with third parties may be subject to disagreements over contract interpretation, which could narrow the scope of our rights to the relevant intellectual property or technology or increase our financial or other obligations to our licensors.

We currently depend, and will continue to depend, on our license agreements, including the license agreements with Cornell University and Adverum related to LX2006, with Cornell University related to our LX1001, LX1020 and LX1021 product candidates, and with UCSD related to LX2020, LX2021 and LX2022 product candidates. The agreements under which we currently license intellectual property or technology from third parties are complex, and certain provisions in such agreements may be susceptible to multiple interpretations. The resolution of any contract interpretation disagreement that may arise could narrow what we believe to be the scope of our rights to the relevant intellectual property or technology, or increase what we believe to be our financial or other obligations under the relevant agreement, either of which could have a material adverse effect on our business, financial condition, results of operations and prospects.

If any of our licenses or material relationships or any in-licenses upon which our licenses are based are terminated or breached, we may:

• lose our rights to develop and market our products;
• lose patent protection for our products;
• experience significant delays in the development or commercialization of our products;
• not be able to obtain any other licenses on acceptable terms, if at all; or
• incur liability for damages.

These risks apply to any agreements that we may enter into in the future for our products or for any future product candidates. If we experience any of the foregoing, it could have a material adverse effect on our business, financial condition, results or operations and prospects.

We cannot be certain that any of our or licensed pending patent applications or our future owned or licensed patent applications will result in issued patent claims covering such aspects of our product candidates.

Composition-of-matter patents on the active pharmaceutical ingredient, or API, in prescription drug products are generally considered to be the strongest form of intellectual property protection for drug products because those types of patents provide protection without regard to any particular method of use or manufacture or formulation of the API used. Although we intend to file patent applications in the future that cover these product candidates, we cannot be certain that our future owned or licensed patent applications will cover our current or future product candidates.

Method-of-use patents protect the use of a product for the specified method and formulation patents cover formulations of the API. These types of patents do not prevent a competitor or other third party from developing or marketing an identical product for an indication that is outside the scope of the patented method or from developing a different formulation that is outside the scope of the patented formulation. Moreover, with respect to method-of-use patents, even if competitors or other third parties do not actively promote their product for our targeted indications or uses for which we may obtain patents, physicians may recommend that patients use these products off-label, or patients may do so themselves. Although off-label use may infringe or contribute to the infringement of method-of-use patents, the practice is common, and this type of infringement is difficult to prevent or prosecute. In addition, there are numerous publications and other prior art that may be relevant to our owned or in-licensed method-of-use patents and patent applications and may be used to challenge the validity of these owned or in-licensed patents and patent applications in litigation or other intellectual property-related proceedings. If these types of challenges are successful, our owned or in-licensed patents and patent applications may be narrowed or found to be invalid, and we may lose valuable intellectual property rights. Any of the foregoing could have a material adverse effect on our business, financial conditions, prospects and results of operations.

The strength of patents in the biotechnology and pharmaceutical field involves complex legal and scientific questions and can be uncertain. The patent applications that we own or in-license may fail to result in issued patents with claims that cover our product candidates or uses thereof in the United States or in other countries. Even if patents do successfully issue, the issuance of a patent is not conclusive as to its inventorship, scope, validity or enforceability and third parties may challenge the validity, enforceability or scope of our owned and licensed patents in courts or patent offices in the United States and abroad, which may result in those patents being narrowed, invalidated or held unenforceable. Furthermore, even if they are unchallenged, our owned and licensed patents and pending patent applications, if issued, may not adequately protect our intellectual property or prevent competitors or others from designing around our patent claims to circumvent our owned or licensed patents by developing similar or alternative technologies or therapeutics in a non-infringing manner. If the breadth or strength of protection provided by the patents and patent applications we own or license with respect to our product candidates is not sufficient to impede such competition or is otherwise threatened, it could dissuade companies from collaborating with us to develop, and threaten our ability to commercialize, our product candidates. Any of the foregoing could have a material adverse effect on our business, financial condition, results of operations and prospects.

We may be involved in lawsuits to protect or enforce our patents, which could be expensive, time-consuming and unsuccessful.

Competitors may infringe the patents for which we have applied. To counter infringement or unauthorized use, we may be required to file infringement claims, which can be expensive and time-consuming. If we initiate legal proceedings against a third party to enforce a patent covering one of our product candidates, the defendant could counterclaim that the patent covering our product or product candidate is invalid and/or unenforceable. In patent litigation in the United States, counterclaims alleging invalidity and/or unenforceability are common, and there are numerous grounds upon which a third party can assert invalidity or unenforceability of a patent. In an infringement proceeding, a court may decide that the patent claims we are asserting are invalid and/or unenforceable, or may refuse to stop the other party from using the technology at issue on the grounds that our patent claims do not cover the technology in question. Third parties may also raise similar claims before administrative bodies in the United States or abroad, even outside the context of litigation. Such mechanisms include re-examination, post-grant review, inter partes review and equivalent proceedings in foreign jurisdictions (for example, opposition proceedings). Such proceedings could result in revocation of or amendment to our patents in such a way that they no longer cover our product candidates. The outcome following legal assertions of invalidity and unenforceability is unpredictable. With respect to the validity question, for example, we cannot be certain that there is no invalidating prior art, of which we, our patent counsel and the patent examiner were unaware during prosecution. If a defendant were to prevail on a legal assertion of invalidity and/or unenforceability, we would lose at least part, and perhaps all, of the patent protection on our product candidates. An adverse result in any litigation or defense proceedings could put one or more of our patents at risk of being invalidated or interpreted narrowly, could put our patent applications at risk of not issuing and could have a material adverse impact on our business.

Interference proceedings provoked by third parties or brought by us may be necessary to determine the priority of inventions with respect to our patent applications. An unfavorable outcome could require us to cease using the related technology or force us to take a license under the patent rights of the prevailing party, if available. Furthermore, our business could be harmed if the prevailing party does not offer us a license on commercially reasonable terms. Our defense of litigation or interference proceedings may fail and, even if successful, may result in substantial costs and distract our management and other employees. We may not be able to prevent misappropriation of our intellectual property rights, particularly in countries where the laws may not protect those rights as fully as in the United States.

Even if we establish infringement of any of our patents by a competitive product, a court may decide not to grant an injunction against further infringing activity, thus allowing the competitive product to continue to be marketed by the competitor. It is difficult to obtain an injunction in U.S. litigation and a court could decide that the competitor should instead pay us a “reasonable royalty” as determined by the court, and/or other monetary damages. A reasonable royalty or other monetary damages may or may not be an adequate remedy. Loss of exclusivity and/or competition from a related product would have a material adverse impact on our business.

For certain of our in-licensed patent rights, such as patent rights in-licensed from Cornell University and Adverum, we may not have the right to file a lawsuit for infringement and may have to rely on a licensor to enforce these rights for us. If we are not able to directly assert our licensed patent rights against infringers or if a licensor does not vigorously prosecute any infringement claims on our behalf, we may have difficulty competing in certain markets where such potential infringers conduct their business, and our commercialization efforts may suffer as a result.

In addition, we or our licensors, as the case may be, may not be able to detect infringement against our owned or in-licensed patents, which may be especially difficult for manufacturing processes or formulation patents. Even if we or our licensors detect infringement by a third party of our owned or in-licensed patents, we or our licensors, as the case may be, may choose not to pursue litigation against or settlement with the third party. If we or our licensors later sue such third party for patent infringement, the third party may have certain legal defenses available to it that otherwise would not be available but for the delay between when the infringement was first detected and when the suit was brought. These legal defenses may make it impossible for us or our licensors to enforce our owned or in-licensed patents, as the case may be, against that third party.

Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation, there is a risk that some of our confidential information could be compromised by disclosure during this type of litigation. There could also be public announcements of the results of hearings, motions, or other interim proceedings or developments. If securities analysts or investors perceive these results to be negative, it could have a material adverse effect on the price of our common stock.

Third parties may initiate legal proceedings alleging that we are infringing their intellectual property rights, the outcome of which would be uncertain.

As our current and future product candidates progress toward commercialization, the possibility of a patent infringement claim against us increases. We cannot provide any assurance that our current and future product candidates do not infringe other parties’ patents or other proprietary rights, and competitors or other parties may assert that we infringe their proprietary rights in any event. We may become party to, or threatened with, adversarial proceedings or litigation regarding intellectual property rights with respect to our current and future product candidates, including interference or derivation proceedings before the USPTO, or oppositions and other proceedings in foreign jurisdictions. We may be exposed to, or threatened with, future litigation by third parties having patent or other intellectual property rights alleging that our product candidates, manufacturing methods, formulations, administration methods and/or proprietary technologies infringe, misappropriate or otherwise violate their intellectual property rights.

Numerous issued patents and pending patent applications that are owned by third parties exist in the fields in which we are developing our product candidates. As the biotechnology and pharmaceutical industries expand and more patents are issued, the risk increases that our product candidates may give rise to claims of infringement of the patent rights of others. Moreover, it is not always clear to industry participants, including us, the claim scope that may issue from pending patent applications owned by third parties or which patents cover various types of drugs, products or their methods of use or manufacture. Thus, because of the large number of patents issued and patent applications filed in our fields, there may be a risk that third parties, including our competitors, may allege they have patent rights encompassing our product candidates, technologies or methods and that we are employing their proprietary technology without authorization.

If we were sued for patent infringement, we would need to demonstrate that the relevant product or methods of using the product either do not infringe the patent claims of the relevant patent or that the patent claims are invalid or unenforceable, and we may not be able to do this. In order to successfully challenge the validity of any such United States patent in federal court, we would need to overcome a presumption of validity. As this burden is high and requires us to present clear and convincing evidence as to the invalidity of any such United States patent claim, there is no assurance that a court of competent jurisdiction would agree with us and invalidate the claims of any such United States patent. Moreover, given the vast number of patents in our field of technology, we cannot be certain that we do not infringe existing patents or that we will not infringe patents that may be granted in the future.

While we may decide to initiate proceedings to challenge the validity of these or other patents in the future, we may be unsuccessful, and courts or patent offices in the United States and abroad could uphold the validity of any such patent. Furthermore, because patent applications can take many years to issue and may be confidential for 18 months or more after filing, and because pending patent claims can be revised before issuance, there may be applications now pending which may later result in issued patents that may be infringed by the manufacture, use or sale of our product candidates. Regardless of when filed, we may fail to identify relevant third-party patents or patent applications, or we may incorrectly conclude that a third-party patent is invalid or not infringed by our product candidates or activities. If a patent holder believes that one of our product candidates infringes its patent, the patent holder may sue us even if we have received patent protection for our technology. Moreover, we may face patent infringement claims from non-practicing entities that have no relevant drug revenue and against whom our own patent portfolio may thus have no deterrent effect. If a patent infringement suit were threatened or brought against us, we could be forced to stop or delay research, development, manufacturing or sales of the drug or product candidate that is the subject of the actual or threatened suit.

If any third-party patents are held by a court of competent jurisdiction to be valid and enforceable and to cover any of our technology or product candidates, including the manufacturing process of our product candidates, constructs or molecules used in or formed during the manufacturing process, or any final product itself, we could be forced, including by court order, to cease developing, manufacturing or commercializing the infringing product. Alternatively, we may be required to obtain a license from such third party in order to use the infringing technology and continue developing, manufacturing or marketing the infringing product. If we were required to obtain a license to continue to manufacture or market the affected product, we may be required to pay substantial royalties or grant cross-licenses to our patents. We cannot, however, assure that any such license will be available on acceptable terms, if at all. Ultimately, we could be prevented from commercializing a product, or be forced to cease some aspect of our business operations as a result of claims of patent infringement or violation of other intellectual property rights. Further, the outcome of intellectual property litigation is subject to uncertainties that cannot be adequately quantified in advance, including the demeanor and credibility of witnesses and the identity of any adverse party. This is especially true in intellectual property cases that may turn on the testimony of experts as to technical facts upon which experts may reasonably disagree. Furthermore, we may not be able to obtain any required license on commercially reasonable terms or at all. Even if we were able to obtain a license, it could be non-exclusive, thereby giving our competitors access to the same technologies licensed to us; alternatively, or additionally, it could include terms that impede or destroy our ability to compete successfully in the commercial marketplace. In addition, we could be found liable for significant monetary damages, including treble damages and attorneys’ fees if we are found to have willfully infringed a patent. A finding of infringement could prevent us from commercializing a product or force us to cease some of our business operations, which could harm our business. Claims that we have misappropriated the confidential information or trade secrets of third parties could have a similar negative impact on our business. Furthermore, because of the substantial amount of discovery required in connection with intellectual property litigation or administrative proceedings, there is a risk that some of our confidential information could be compromised by disclosure. In addition, any uncertainties resulting from the initiation and continuation of any litigation could have material adverse effect on our ability to raise additional funds or otherwise have a material adverse effect on our business, results of operations, financial condition and prospects.

The cost to us in defending or initiating any litigation or other proceeding relating to patent or other proprietary rights, even if resolved in our favor, could be substantial, and litigation would divert our management’s attention. Some of our competitors may be able to sustain the costs of complex patent litigation more effectively than we can because they have substantially greater resources. Uncertainties resulting from the initiation and continuation of patent litigation or other proceedings could delay our research and development efforts and limit our ability to continue our operations.

We may become subject to claims that we and our employees, consultants, or independent contractors have wrongfully used or disclosed confidential information or trade secrets of third parties.

We employ individuals who were previously employed at other biotechnology or biopharmaceutical companies. Although we require, evidenced by written agreements, that all of our employees, consultants and advisors not use the proprietary information or know-how of others in their work for us, we may be subject to claims that we or our employees, consultants, or independent contractors have inadvertently or otherwise used or disclosed confidential information of our employees’ former employers or other third parties. We may also be subject to claims that former employers or other third parties have an ownership interest in our future patents. Litigation may be necessary to defend against these claims, and there is no guarantee of success in defending these claims.

Even if we are successful in defending against these types of claims, litigation or other legal proceedings relating to intellectual property claims may cause us to incur significant expenses and could distract our technical and management personnel from their normal responsibilities. In addition, there could be public announcements of the results of hearings, motions or other interim proceedings or developments, and, if securities analysts or investors perceive these results to be negative, that perception could have a substantial adverse effect on the price of our common stock. This type of litigation or proceeding could substantially increase our operating losses and reduce our resources available for development activities. Some of our competitors may be able to sustain the costs of this type of litigation or proceedings more effectively than we can because of their substantially greater financial resources. Uncertainties resulting from the initiation and continuation of intellectual property litigation or other intellectual property related proceedings could adversely affect our ability to compete in the marketplace.

For additional information regarding our legal proceedings, see Note 11 to the condensed financial statements included in Part I, Item 1 of this Quarterly Report on Form 10-Q.

We may be subject to claims challenging the inventorship or ownership of our future patents and other intellectual property.

We may also be subject to claims that former employees, collaborators, or other third parties have an ownership interest in our patent applications, our future patents, or other intellectual property. We may be subject to ownership disputes in the future arising, for example, from conflicting obligations of consultants or others who are involved in developing our product candidates and platform discovery. Although it is our policy to require our employees and contractors who may be involved in the conception or development of intellectual property to execute agreements assigning such intellectual property to us, we may be unsuccessful in executing such an agreement with each party who, in fact, conceives or develops intellectual property that we regard as our own, and we cannot be certain that our agreements with such parties will be upheld in the face of a potential challenge, or that they will not be breached, for which we may not have an adequate remedy. The assignment of intellectual property rights may not be self-executing, or the assignment agreements may be breached, and litigation may be necessary to defend against these and other claims challenging inventorship or ownership. If we fail in defending any such claims, in addition to paying monetary damages, we may lose valuable intellectual property rights, such as exclusive ownership of, or right to use, valuable intellectual property. Such an outcome could have a material adverse effect on our business. Even if we are successful in defending against such claims, litigation could result in substantial costs and be a distraction to management and other employees.

Reliance on third parties requires us to share our trade secrets, which increases the possibility that a competitor will discover them or that our trade secrets will be misappropriated or disclosed.

If we rely on third parties to manufacture or commercialize our product candidates, or if we collaborate with additional third parties for the development of such product candidates, we must, at times, share trade secrets with them. We may also conduct joint research and development programs that may require us to share trade secrets under the terms of our research and development partnerships or similar agreements. We seek to protect our proprietary technology in part by entering into confidentiality agreements and, if applicable, material transfer agreements, consulting agreements or other similar agreements with our advisors, employees, third-party contractors and consultants prior to beginning research or disclosing proprietary information. These agreements typically limit the rights of the third parties to use or disclose our confidential information, including our trade secrets. Despite the contractual provisions employed when working with third parties, the need to share trade secrets and other confidential information increases the risk that such trade secrets become known by our competitors, are inadvertently incorporated into the technology of others, or are disclosed or used in violation of these agreements. Given that our proprietary position is based, in part, on our know-how and trade secrets, a competitor’s discovery of our trade secrets or other unauthorized use or disclosure could have an adverse effect on our business and results of operations.

In addition, these agreements typically restrict the ability of our advisors, employees, third-party contractors and consultants to publish data potentially relating to our trade secrets. Despite our efforts to protect our trade secrets, we may not be able to prevent the unauthorized disclosure or use of our technical know-how or other trade secrets by the parties to these agreements. Moreover, we cannot guarantee that we have entered into such agreements with each party that may have or have had access to our confidential information or proprietary technology and processes. Monitoring unauthorized uses and disclosures is difficult, and we do not know whether the steps we have taken to protect our proprietary technologies will be effective. If any of the collaborators, scientific advisors, employees, contractors and consultants who are parties to these agreements breaches or violates the terms of any of these agreements, we may not have adequate remedies for any such breach or violation, and we could lose our trade secrets as a result. Moreover, if confidential information that is licensed or disclosed to us by our partners, collaborators, or others is inadvertently disclosed or subject to a breach or violation, we may be exposed to liability to the owner of that confidential information. Enforcing a claim that a third party illegally obtained and is using our trade secrets, like patent litigation, is expensive and time consuming, and the outcome is unpredictable. In addition, courts outside the United States are sometimes less willing to protect trade secrets.

Intellectual property rights do not necessarily address all potential threats to our competitive advantage.

The degree of future protection afforded by our intellectual property rights is uncertain because intellectual property rights have limitations, and may not adequately protect our business, or permit us to maintain our competitive advantage. The following examples are illustrative:

• others may be able to make or use capsids, nucleic acids and vectors that are similar to the biological compositions of our products that are the same as or similar to our product candidates but that are not covered by the claims of owned or in-licensed patents;

• others may independently develop similar or alternative technologies or duplicate any of our technologies;

• it is possible that others may circumvent our owned or in-licensed patents;

• others, including inventors or developers of our owned or in-licensed patented technologies who may become involved with competitors, may independently develop similar technologies that function as alternatives or replacements for any of our technologies without infringing our intellectual property rights;

• it is possible that our owned or in-licensed patents or patent applications omit individual(s) who should be listed as inventor(s) or include individual(s) who should not be listed as inventor(s), which may cause these patents or patents issuing from these patent applications to be held invalid or unenforceable;

• we or our licensors or our other collaboration partners might not have been the first to conceive and reduce to practice the inventions covered by the patents or patent applications that we own, license or will own or license;

• we or our licensors or our other collaboration partners might not have been the first to file patent applications covering certain of the patents or patent applications that we or they own or have obtained a license, or will own or will have obtained a license;

• we or our licensors may fail to meet obligations to the U.S. government with respect to in-licensed patents and patent applications funded by U.S. government grants, leading to the loss of patent rights;

• it is possible that our pending patent applications will not result in issued patents;

• we may not be able to generate sufficient data to support full patent applications that protect the entire breadth of developments in one or more of our programs;

• no patent protection may be available with regard to formulation or method of use;

• the claims of our owned or in-licensed issued patents or patent applications, if and when issued, may not cover our product candidates;

• it is possible that there are prior public disclosures that could invalidate our or our licensors’ patents;

• it is possible that there are unpublished applications or patent applications maintained in secrecy that may later issue with claims covering our products or technology similar to ours;

• issued patents that we own or exclusively license may not provide us with any competitive advantage, or may be held invalid or unenforceable, as a result of legal challenges by our competitors;

• we may not exclusively license our patents and, therefore, may not have a competitive advantage if such patents are licensed to others;

• our competitors might conduct research and development activities in countries where we do not have patent rights, or in countries where research and development safe harbor laws exist, and then use the information learned from such activities to develop competitive products for sale in our major commercial markets;

• the laws of other countries may not protect our or our licensors’, as the case may be, proprietary rights to the same extent as the laws of the United States;

• there may be significant pressure on the U.S. government and international governmental bodies to limit the scope of patent protection both inside and outside the United States for disease treatments that prove successful, as a matter of public policy regarding worldwide health concerns;

• countries other than the United States may, under certain circumstances, force us or our licensors to grant a license under our patents to a competitor, thus allowing the competitor to compete with us in that jurisdiction or forcing us to lower the price of our drug in that jurisdiction;

• we have engaged in scientific collaborations in the past and will continue to do so in the future and our collaborators may develop adjacent or competing products that are outside the scope of our patents;

• we may not successfully commercialize the product candidates, if approved, before our relevant patents expire;

• we may not develop additional proprietary technologies for which we can obtain patent protection;

• it is possible that product candidates or technologies we develop may be covered by third parties’ patents or other exclusive rights;

• ownership, validity or enforceability of our or our licensors’ patents or patent applications may be challenged by third parties; and

• the patents of third parties or pending or future applications of third parties, if issued, may have an adverse effect on our business.

We may have limited geographical protection with respect to certain patents and we may not be able to protect our intellectual property rights throughout the world.

Filing and prosecuting patent applications and defending patents covering our product candidates in all countries throughout the world would be prohibitively expensive. Competitors may use our technologies in jurisdictions where we have not obtained patent protection to develop their own products and, further, may export otherwise infringing products to territories where we have patent protection, but enforcement rights are not as strong as that in the United States or Europe. These products may compete with our product candidates, and our future patents or other intellectual property rights may not be effective or sufficient to prevent them from competing.

In addition, we may decide to abandon national and regional patent applications before they are granted. The examination of each national or regional patent application is an independent proceeding. As a result, patent applications in the same family may issue as patents in some jurisdictions, such as in the United States, but may issue as patents with claims of different scope or may even be refused in other jurisdictions. It is also quite common that depending on the country, the scope of patent protection may vary for the same product candidate or technology.

While we intend to protect our intellectual property rights in our expected significant markets, we cannot ensure that we will be able to initiate or maintain similar efforts in all jurisdictions in which we may wish to market our product candidates. Accordingly, our efforts to protect our intellectual property rights in such countries may be inadequate, which may have an adverse effect on our ability to successfully commercialize our product candidates in all of our expected significant foreign markets. If we encounter difficulties in protecting, or are otherwise precluded from effectively protecting, the intellectual property rights important for our business in such jurisdictions, the value of these rights may be diminished, and we may face additional competition from others in those jurisdictions.

The laws of some jurisdictions do not protect intellectual property rights to the same extent as the laws or rules and regulations in the United States and Europe and many companies have encountered significant difficulties in protecting and defending such rights in such jurisdictions. The legal systems of certain countries, particularly certain developing countries, do not favor the enforcement of patents, trade secrets and other intellectual property rights, which could make it difficult for us to stop the infringement of our future patents or marketing of competing products in violation of our proprietary rights generally. Proceedings to enforce our patent rights in other jurisdictions, whether or not successful, could result in substantial costs and divert our efforts and attention from other aspects of our business, could put our future patents at risk of being invalidated or interpreted narrowly and our patent applications at risk of not issuing as patents, and could provoke third parties to assert claims against us. We may not prevail in any lawsuits that we initiate, and the damages or other remedies awarded, if any, may not be commercially meaningful. Accordingly, our efforts to enforce our intellectual property rights around the world may be inadequate to obtain a significant commercial advantage from the intellectual property that we develop or license.

Some countries also have compulsory licensing laws under which a patent owner may be compelled to grant licenses to third parties. In addition, some countries limit the enforceability of patents against government agencies or government contractors. In those countries, the patent owner may have limited remedies, which could materially diminish the value of such patents. If we are forced to grant a license to third parties with respect to any patents relevant to our business, our competitive position may be impaired.

Obtaining and maintaining our patent protection depends on compliance with various procedural, document submission, fee payment and other requirements imposed by government patent agencies, and our patent protection could be reduced or eliminated for non-compliance with these requirements.

Periodic maintenance fees, renewal fees, annuity fees and various other government fees on patents and/or applications will be due to be paid to the USPTO and various government patent agencies outside of the United States over the lifetime of our patents and/or applications and any patent rights we may obtain in the future. Furthermore, the USPTO and various non-United States government patent agencies require compliance with several procedural, documentary, fee payment and other similar provisions during the patent application process. In many cases, an inadvertent lapse of a patent or patent application can be cured by payment of a late fee or by other means in accordance with the applicable rules. There are situations, however, in which non-compliance can result in abandonment or lapse of the patents or patent applications, resulting in partial or complete loss of patent rights in the relevant jurisdiction. In such an event, potential competitors might be able to enter the market, which could have a material adverse effect on our business.

Changes in patent laws or patent jurisprudence could diminish the value of patents in general, thereby impairing our ability to protect our product candidates.

As is the case with other biotechnology companies, our success is heavily dependent on intellectual property, particularly patents. Obtaining and enforcing patents in the biotechnology and genetic medicine industries involve both technological and legal complexity. Therefore, obtaining and enforcing biotechnology and genetic medicine patents is costly, time-consuming and inherently uncertain. In addition, the Leahy-Smith America Invents Act, or the AIA, which was passed in September 2011, resulted in significant changes to the U.S. patent system.

An important change introduced by the AIA is that, as of March 16, 2013, the United States transitioned from a “first-to-invent” to a “first-to-file” system for deciding which party should be granted a patent when two or more patent applications are filed by different parties claiming the same invention. Under a “first-to-file” system, assuming the other requirements for patentability are met, the first inventor to file a patent application generally will be entitled to a patent on the invention regardless of whether another inventor had made the invention earlier. A third party that files a patent application in the USPTO after that date but before us could therefore be awarded a patent covering an invention of ours even if we made the invention before it was made by the third party. This will require us to be cognizant going forward of the time from invention to filing of a patent application and be diligent in filing patent applications, but circumstances could prevent us from promptly filing patent applications on our inventions.

Among some of the other changes introduced by the AIA are changes that limit where a patentee may file a patent infringement suit and provide opportunities for third parties to challenge any issued patent in the USPTO. This applies to all of our U.S. patents, even those issued before March 16, 2013. Because of a lower evidentiary standard in USPTO proceedings compared to the evidentiary standard in U.S. federal courts necessary to invalidate a patent claim, a third party could potentially provide evidence in a USPTO proceeding sufficient for the USPTO to hold a claim invalid even though the same evidence would be insufficient to invalidate the claim if first presented in a district court action.

Accordingly, a third party may attempt to use the USPTO procedures to invalidate our patent claims that would not have been invalidated if first challenged by the third party as a defendant in a district court action. It is not clear what, if any, impact the AIA will have on the operation of our business. However, the AIA and its implementation could increase the uncertainties and costs surrounding the prosecution of our or our licensors’ patent applications and the enforcement or defense of our or our licensors’ issued patents.

We may become involved in opposition, interference, derivation, inter partes review or other proceedings challenging our or our licensors’ patent rights, and the outcome of any proceedings are highly uncertain. An adverse determination in any such proceeding could reduce the scope of, or invalidate, our owned or in-licensed patent rights, allow third parties to commercialize our technology or products and compete directly with us, without payment to us, or result in our inability to manufacture or commercialize products without infringing third-party patent rights.

In addition, the United States federal government retains certain rights in inventions produced with its financial assistance under the Bayh-Dole Act. The federal government retains a “nonexclusive, nontransferable, irrevocable, paid-up license” for its own benefit. The Bayh-Dole Act also provides federal agencies with “march-in rights.” March-in rights allow the government, in specified circumstances, to require the contractor or successors in title to the patent to grant a “nonexclusive, partially exclusive, or exclusive license” to a “responsible applicant or applicants.” If the patent owner refuses to do so, the government may grant the license itself. Some of our licensed patents are subject to the provisions of the Bayh-Dole Act. If our licensors fail to comply with the regulations of the Bayh-Dole Act, they could lose title to any patents subject to such regulations, which could affect our license rights under the patents and our ability to stop others from using or commercializing similar or identical technology and products, or limit patent protection for our technology and products.

Additionally, the U.S. Supreme Court has ruled on several patent cases in recent years either narrowing the scope of patent protection available in certain circumstances or weakening the rights of patent owners in certain situations, and there are other open questions under patent law that courts have yet to decisively address. In addition to increasing uncertainty with regard to our ability to obtain patents in the future, this combination of events has created uncertainty with respect to the value of patents once obtained. Depending on decisions by Congress, the federal courts and the USPTO, the laws and regulations governing patents could change in unpredictable ways and could weaken our ability to obtain new patents or to enforce our existing patents and patents that we might obtain in the future. In addition, the European patent system is relatively stringent in the type of amendments that are allowed during prosecution, but the complexity and uncertainty of European patent laws has also increased in recent years. Complying with these laws and regulations could limit our ability to obtain new patents in the future that may be important for our business.

If our trademarks and trade names are not adequately protected, then we may not be able to build name recognition in our markets of interest and our business may be adversely affected.

Our current or future trademarks or trade names may be challenged, infringed, circumvented or declared generic or descriptive or determined to be infringing on other marks. We may not be able to protect our rights to these trademarks and trade names or may be forced to stop using these names, which we need for name recognition by potential partners or customers in our markets of interest. During trademark registration proceedings, we may receive rejections of our applications by the USPTO or in other foreign jurisdictions. Although we would be given an opportunity to respond to those rejections, we may be unable to overcome such rejections. In addition, in the USPTO and in comparable agencies in many foreign jurisdictions, third parties are given an opportunity to oppose pending trademark applications and to seek to cancel registered trademarks. Opposition or cancellation proceedings may be filed against our trademarks, and our trademarks may not survive such proceedings. If we are unable to establish name recognition based on our trademarks and trade names, we may not be able to compete effectively and our business may be adversely affected. We may license our trademarks and trade names to third parties, such as distributors. Although these license agreements may provide guidelines for how our trademarks and trade names may be used, a breach of these agreements or misuse of our trademarks and tradenames by our licensees may jeopardize our rights in or diminish the goodwill associated with our trademarks and trade names.

Moreover, any name we have proposed to use with our product candidate in the United States must be approved by the FDA, regardless of whether we have registered it, or applied to register it, as a trademark. Similar requirements exist in Europe. The FDA typically conducts a review of proposed product names, including an evaluation of potential for confusion with other product names. If the FDA (or an equivalent administrative body in a foreign jurisdiction) objects to any of our proposed proprietary product names, we may be required to expend significant additional resources in an effort to identify a suitable substitute name that would qualify under applicable trademark laws, not infringe the existing rights of third parties and be acceptable to the FDA. Furthermore, in many countries, owning and maintaining a trademark registration may not provide an adequate defense against a subsequent infringement claim asserted by the owner of a senior trademark. At times, competitors or other third parties may adopt trade names or trademarks similar to ours, thereby impeding our ability to build brand identity and possibly leading to market confusion. In addition, there could be potential trade name or trademark infringement claims brought by owners of other registered trademarks or trademarks that incorporate variations of our registered or unregistered trademarks or trade names. If we assert trademark infringement claims, a court may determine that the marks we have asserted are invalid or unenforceable, or that the party against whom we have asserted trademark infringement has superior rights to the marks in question. In this case, we could ultimately be forced to cease use of such trademarks.

Risks related to legal and regulatory compliance matters

Our current and future relationships with customers, healthcare providers, including physicians, and third- party payors may be subject, directly or indirectly, to federal and state healthcare fraud and abuse laws, false claims laws, health information privacy and security laws and other healthcare laws and regulations. If we are unable to comply, or have not fully complied, with such laws, we could face substantial penalties.

We are currently or will in the future be subject to healthcare regulation and enforcement by the U.S. federal government and the states in which we will conduct our business once our product candidates are approved by the FDA and commercialized in the United States. In addition to the FDA’s restrictions on marketing of pharmaceutical products, the U.S. healthcare laws and regulations that may affect our ability to operate include: the federal fraud and abuse laws, including the federal anti-kickback and false claims laws; federal data privacy and security laws; and federal transparency laws related to payments and/or other transfers of value made to physicians and other healthcare professionals and teaching hospitals. Many states have similar laws and regulations that may differ from each other and federal law in significant ways, thus complicating compliance efforts. For example, states have anti-kickback and false claims laws that may be broader in scope than analogous federal laws and may apply regardless of payor. In addition, state laws regarding the privacy and security of health information may differ from each other and may not be preempted by federal law. Moreover, several states have enacted legislation requiring pharmaceutical manufacturers to, among other things, establish marketing compliance programs, file periodic reports with the state, make periodic public disclosures on sales and marketing activities, report information related to drug pricing, require the registration of sales representatives, and prohibit certain other sales and marketing practices. These laws may adversely affect our sales, marketing and other activities with respect to any product candidate for which we receive approval to market in the United States by imposing administrative and compliance burdens on us. It is possible that governmental authorities will conclude that our current or future business practices may not comply with current or future statutes, regulations or case law involving applicable fraud and abuse or other healthcare laws and regulations. If our operations are found to be in violation of any of these laws or any other governmental regulations that may apply to us, we may be subject to significant penalties, including, without limitation, civil, criminal and administrative penalties, damages, fines, disgorgement, individual imprisonment, exclusion from participating in federal and state funded healthcare programs, such as Medicare and Medicaid, additional reporting requirements and oversight if we become subject to a corporate integrity agreement or similar agreement to resolve allegations of non-compliance with these laws, contractual damages, diminished profits and future earnings, reputational harm and the curtailment or restructuring of our operations, any of which could harm our business.

The risk of being found in violation of these laws is increased by the fact that many of them have not been fully interpreted by the regulatory authorities or the courts, and their provisions are open to a variety of interpretations. Efforts to ensure that our business arrangements with third parties will comply with applicable healthcare laws and regulations will involve substantial costs. Any action against us for violation of these laws, even if we successfully defend against it, could cause us to incur significant legal expenses and divert our management’s attention from the operation of our business. The shifting compliance environment and the need to build and maintain robust and expandable systems to comply with multiple jurisdictions with different compliance and/or reporting requirements increases the possibility that a healthcare company may run afoul of one or more of the requirements.

Even if we obtain FDA or EMA approval for any of our product candidates in the United States or European Union, we may never obtain approval for or commercialize any of them in any other jurisdiction, which would limit our ability to realize their full market potential.

In order to market any products in any particular jurisdiction, we must establish and comply with numerous and varying regulatory requirements on a country-by-country basis regarding safety and efficacy.

Approval by the FDA in the United States or the EMA in the European Union does not ensure approval by regulatory authorities in other countries or jurisdictions. However, the failure to obtain approval in one jurisdiction may negatively impact our ability to obtain approval elsewhere. In addition, clinical trials conducted in one country may not be accepted by regulatory authorities in other countries, and regulatory approval in one country does not guarantee regulatory approval in any other country.

Approval processes vary among countries and can involve additional product testing and validation and additional administrative review periods. Seeking foreign regulatory approval could result in difficulties and increased costs for us and require additional preclinical studies or clinical trials which could be costly and time consuming.

Regulatory requirements can vary widely from country to country and could delay or prevent the introduction of our products in those countries. We do not have any product candidates approved for sale in any jurisdiction, including in international markets. If we fail to comply with regulatory requirements in international markets or to obtain and maintain required approvals, or if regulatory approvals in international markets are delayed, our target market will be reduced and our ability to realize the full market potential of any product we develop will be unrealized.

Even if we receive regulatory approval of our product candidates, we will be subject to ongoing regulatory obligations and continued regulatory review, which may result in significant additional expense, and we may be subject to penalties if we fail to comply with regulatory requirements or experience unanticipated problems with our product candidates.

Any product candidate for which we obtain marketing approval will be subject to ongoing regulatory requirements for, among other things, manufacturing processes, submission of post-approval clinical data and safety information, labeling, packaging, distribution, adverse event reporting, storage, recordkeeping, export, import, advertising, promotional activities and product tracking and tracing. These requirements include submissions of safety and other post-marketing information and reports, establishment registration and drug listing requirements, applicable tracking and tracing requirements, continued compliance with cGMP requirements relating to manufacturing, quality control, quality assurance and corresponding maintenance of records and documents, requirements regarding the distribution of samples to physicians and recordkeeping and cGCP requirements for any clinical trials that we conduct post-approval.

Any regulatory approvals that we receive for our product candidates or any future product candidates may also be subject to a REMS, limitations on the approved indicated uses for which the product may be marketed or to the conditions of approval, or requirements that we conduct potentially costly post-marketing testing, including Phase 4 trials and surveillance to monitor the quality, safety and efficacy of the product. An unsuccessful post- marketing study or failure to complete such a study could result in the withdrawal of marketing approval. We will further be required to immediately report any serious and unexpected adverse events and certain quality or production problems with our products to regulatory authorities along with other periodic reports.

The FDA and EMA closely regulate the post-approval marketing and promotion of genetic therapy medicines to ensure they are marketed only for the approved indications and in accordance with the provisions of the approved labeling. However, companies may share truthful and not misleading information that is otherwise consistent with a product’s FDA approved labeling. The FDA imposes stringent restrictions on manufacturers’ communications regarding off-label use and if we market our products for uses beyond their approved diseases, we may be subject to enforcement action for off-label marketing. Violations of the FDCA, relating to the promotion of prescription drugs for unapproved uses may lead to enforcement actions and investigations alleging violations of federal and state health care fraud and abuse laws, as well as state consumer protection laws. The holder of an approved BLA must submit new or supplemental applications and obtain prior approval for certain changes to the approved product, product labeling, or manufacturing process. A company that is found to have improperly promoted off-label uses of their products may be subject to significant civil, criminal and administrative penalties.

In addition, later discovery of previously unknown adverse events or other problems with our products, manufacturers or manufacturing processes, including adverse events of unanticipated severity or frequency, or with our third-party manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may yield various results, including:

• restrictions on manufacturing such products;

• restrictions on the labeling or marketing of a product;

• restrictions on product distribution or use;

• refusal to allow entry into supply contracts, including government contracts;

• requirements to conduct post-marketing studies or clinical trials;

• warning or untitled letters, or holds on clinical trials;

• withdrawal of the products from the market;

• refusal to approve pending applications or supplements to approved applications that we submit;

• recall of products;

• fines, restitution or disgorgement of profits or revenues;

• suspension or withdrawal of marketing approvals;

• refusal to permit the import or export of our products;

• product seizure or detention; or

• injunctions or the imposition of administrative, civil or criminal penalties or monetary fines.

The FDA’s policies, and the policies of foreign regulatory agencies, may change and additional government regulations may be enacted that could prevent, limit or delay regulatory approval of our product candidates.

We also cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative or executive action, either in the United States or abroad. For example, executive orders or other actions could impose significant burdens on, or otherwise materially delay, the FDA’s ability to engage in routine oversight activities such as implementing statutes through rulemaking, issuance of guidance, and review and approval of marketing applications. If such executive actions were to impose restrictions on the FDA’s ability to engage in oversight and implementation activities in the normal course, our business could be negatively impacted. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained which would adversely affect our business, prospects and ability to achieve or sustain profitability.

Any government investigation of alleged violations of law could require us to expend significant time and resources in response and could generate negative publicity. The occurrence of any event or penalty described above may inhibit our ability to commercialize our current product candidates or any future product candidates and harm our business, financial condition, results of operations and prospects.

Enacted and future healthcare legislation may increase the difficulty and cost for us to progress our clinical programs and obtain marketing approval of and commercialize our product candidates and may affect the prices we may set.

In the United States, the European Union and other jurisdictions, there have been, and we expect there will continue to be, a number of legislative and regulatory changes and proposed changes to the healthcare system that could affect our future results of operations. In particular, there have been and continue to be a number of initiatives at the U.S. federal and state levels that seek to reduce healthcare costs and improve the quality of healthcare.

The continuing efforts of the government, insurance companies, managed care organizations and other payers of healthcare services to contain or reduce costs of healthcare may adversely affect:

• the demand for any of our product candidates, if approved;
• the ability to set a price that we believe is fair for any of our product candidates, if approved;
• our ability to generate revenues and achieve or maintain profitability;
• the level of taxes that we are required to pay; and
• the availability of capital.

Legislative and regulatory proposals have been made to expand post-approval requirements and restrict sales and promotional activities for pharmaceutical and biologic products. We cannot be sure whether additional legislative changes will be enacted, or whether FDA regulations, guidance or interpretations will be changed, or what the impact of such changes on the marketing approvals of our product candidates, if any, may be. In addition, increased scrutiny by Congress of the FDA’s approval process may significantly delay or prevent marketing approval, as well as subject us to more stringent product labeling and post-marketing testing and other requirements.

Moreover, payment methodologies may be subject to changes in healthcare legislation and regulatory initiatives. For example, CMS may develop new payment and delivery models, such as bundled payment models. In addition, recently there has been heightened governmental scrutiny over the manner in which manufacturers set prices for their marketed products, which has resulted in several U.S. presidential executive orders, Congressional inquiries and proposed and enacted federal legislation designed to, among other things, bring more transparency to drug pricing, reduce the cost of prescription drugs under Medicare, and review the relationship between pricing and manufacturer patient programs. In April 2025, the President issued an executive order and an accompanying fact sheet focused on lowering drug prices, but it is unclear what actions will be implemented by the Department of Health and Human Services, CMS, and FDA under the new leadership, and how those actions will impact our industry and our business. We expect that additional U.S. federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that the U.S. federal government will pay for healthcare products and services, which could result in reduced demand for our product candidates or additional pricing pressures and could negatively affect our customers and accordingly, our financial operations.

Individual states in the United States have also increasingly passed legislation and implemented regulations designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. Legally mandated price controls on payment amounts by third-party payors or other restrictions could harm our business, results of operations, financial condition and prospects. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers will be included in their prescription drug and other healthcare programs. This could reduce the ultimate demand for our product candidates or put pressure on our product pricing.

In the European Union, similar political, economic and regulatory developments may affect our ability to profitably commercialize our product candidates, if approved. In addition to continuing pressure on prices and cost containment measures, legislative developments at the European Union or member state level may result in significant additional requirements or obstacles that may increase our operating costs. The delivery of healthcare in the European Union, including the establishment and operation of health services and the pricing and reimbursement of medicines, is almost exclusively a matter for national, rather than European Union, law and policy. National governments and health service providers have different priorities and approaches to the delivery of health care and the pricing and reimbursement of products in that context. In general, however, the healthcare budgetary constraints in most European Union member states have resulted in restrictions on the pricing and reimbursement of medicines by relevant health service providers. Coupled with ever-increasing European Union and national regulatory burdens on those wishing to develop and market products, this could prevent or delay marketing approval of our product candidates, restrict or regulate post-approval activities and affect our ability to commercialize our product candidates, if approved.

In markets outside of the United States and the European Union, reimbursement and healthcare payment systems vary significantly by country, and many countries have instituted price ceilings on specific products and therapies.

We cannot predict the likelihood, nature or extent of government regulation that may arise from future legislation or administrative action in the United States, the European Union or any other jurisdiction. If we or any third parties we may engage are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we or such third parties are not able to maintain regulatory compliance, our product candidates may lose any regulatory approval that may have been obtained and we may not achieve or sustain profitability.

Changes in federal funding, layoffs, government shutdown, staff departures, lapse in government appropriations, and other policies and executive order impacting the normal operations of the FDA and other government agencies could hinder their ability to hire and retain key leadership and other personnel, or otherwise prevent new products and services from being developed or commercialized in a timely manner, any of which could negatively impact our business.

The ability of the FDA to review and approve new products can be affected by a variety of factors, including government budget and funding levels, the current government shutdown, ability to hire and retain key personnel, accept the payment of user fees, and statutory, regulatory and policy changes. Average review times at the agency have fluctuated in recent years as a result. In addition, government funding of other government agencies that fund research and development activities is subject to the political process, which is inherently fluid and unpredictable. Changes in the leadership of the FDA and other federal agencies under the current administration, including return-to-office policy, hiring freeze, layoffs, and other policies implemented by the Department of Government Efficiency, may lead to changes in the operations of the FDA, which may have a material impact on the industry and our clinical development plans.

Disruptions at the FDA and other agencies may also slow the time necessary for new drugs to be reviewed and/or approved by necessary government agencies, which would adversely affect our business. Additionally, changes in the FDA leadership, regulatory actions and other actions under the current administration, may result in delays in regulatory approval. Our business depends upon the ability of the FDA to accept and review our potential regulatory filings. If a prolonged government shutdown occurs or if a significant number of federal employees are laid off or leave federal agencies, it could significantly impact the ability of the FDA to timely review and process our regulatory submissions, which could have a material adverse effect on our ability to advance clinical development of our product candidates, delay our clinical development timelines, and increase the costs of clinical development process.

If we are unable to establish sales, marketing and distribution capabilities either on our own or in collaboration with third parties, we may not be successful in commercializing our product candidates or realizing the synergies in the target diseases of our programs, even if they are approved.

We do not have any infrastructure for the sales, marketing or distribution of our products, and the cost of establishing and maintaining such an organization may exceed the cost-effectiveness of doing so. We expect to build a focused sales, distribution and marketing infrastructure to market our product candidates in the United States and European Union, if approved. There are significant expenses and risks involved with establishing our own sales, marketing and distribution capabilities, including our ability to hire, retain and appropriately incentivize qualified individuals, generate sufficient sales leads, provide adequate training to sales and marketing personnel, and effectively manage a geographically dispersed sales and marketing team. Any failure or delay in the development of our internal sales, marketing and distribution capabilities could delay any product launch, which would adversely impact the commercialization of our product candidates. Additionally, if the commercial launch of our product candidates for which we recruit a sales force and establish marketing capabilities is delayed or does not occur for any reason, we would have prematurely or unnecessarily incurred these commercialization expenses. This may be costly, and our investment would be lost if we cannot retain or reposition our sales and marketing personnel.

We may not have the resources in the foreseeable future to allocate to the sales and marketing of our product candidates in certain international markets. Therefore, our future sales in these markets will largely depend on our ability to enter into and maintain collaborative relationships for such capabilities, the collaborator’s strategic interest in the product and such collaborator’s ability to successfully market and sell the product. We may pursue collaborative arrangements regarding the sale and marketing of LX2006 or LX2020, if approved, for certain markets overseas; however, we cannot assure that we will be able to establish or maintain such collaborative arrangements, or if able to do so, that they will have effective sales forces.

If we are unable to build our own sales force or negotiate a collaborative relationship for the commercialization of LX2006, LX2020 or LX1001, or any of our other product candidates, if approved, we may be forced to delay the potential commercialization of LX2006, or LX2020 or any of our other product candidates or reduce the scope of our sales or marketing activities for LX2006 or LX2020 or any of our other product candidates. If we elect to increase our expenditures to fund commercialization activities internationally, we will need to obtain additional capital, which may not be available to us on acceptable terms, or at all. We could enter into arrangements with collaborative partners at an earlier stage than otherwise would be ideal and we may be required to relinquish rights to LX2006 or LX2020 or any of our other product candidates or otherwise agree to terms unfavorable to us, any of which may have an adverse effect on our business, operating results and prospects.

If we are unable to establish adequate sales, marketing and distribution capabilities, either on our own or in collaboration with third parties, we will not be successful in commercializing LX2006, or LX2020 or any of our other product candidates, if approved, and may not become profitable and may incur significant additional losses. We will be competing with many companies that currently have extensive and well-funded marketing and sales operations. Without an internal team or the support of a third party to perform marketing and sales functions, we may be unable to compete successfully against these more established companies.

If we obtain approval to commercialize any products outside of the United States or the European Union, a variety of risks associated with international operations could adversely affect our business.

If LX2006, LX2020 or any of our other product candidates are approved for commercialization, we may seek to enter into agreements with third parties to market them in certain jurisdictions outside the United States and the European Union. We expect that we would be subject to additional risks related to international pharmaceutical operations, including:

• different regulatory requirements for drug and biologic approvals and rules governing drug and biologic commercialization in foreign countries;

• reduced protection for intellectual property rights;

• foreign reimbursement, pricing and insurance regimes;

• unexpected changes in tariffs, trade barriers and regulatory requirements;

• economic weakness, including inflation, or political instability in particular foreign economies and markets;

• foreign currency fluctuations, which could result in increased operating expenses and reduced revenues, and other obligations incident to doing business in another country;

• business interruptions resulting from geopolitical actions, including war and terrorism or natural disasters including earthquakes, typhoons, floods and fires, or from economic or political instability;

• greater difficulty with enforcing our contracts;

• potential noncompliance with the U.S. Foreign Corrupt Practices Act, or the FCPA, the U.K. Bribery Act 2010 and similar anti-bribery and anticorruption laws in other jurisdictions; and

• production shortages resulting from any events affecting raw material supply or manufacturing capabilities abroad.

In addition, there are complex regulatory, tax, labor and other legal requirements imposed by individual countries in Europe with which we will need to comply. If we are unable to successfully manage the challenges of international expansion and operations, our business and operating results could be harmed.

If we fail to comply with environmental, health and safety laws and regulations, we could become subject to fines or penalties or incur costs that could harm our business.

We are subject to numerous environmental, health and safety laws and regulations, including those governing laboratory procedures and the handling, use, storage, treatment and disposal of hazardous materials and wastes. From time to time and in the future, our operations may involve the use of hazardous and flammable materials, including chemicals and biological materials, and may also produce hazardous waste products. Even if we contract with third parties for the disposal of these materials and waste products, we cannot completely eliminate the risk of contamination or injury resulting from these materials. In the event of contamination or injury resulting from the use or disposal of our hazardous materials, we could be held liable for any resulting damages, and any liability could exceed our resources. We also could incur significant costs associated with civil or criminal fines and penalties for failure to comply with such laws and regulations.

We maintain workers’ compensation insurance to cover us for costs and expenses we may incur due to injuries to our employees, but this insurance may not provide adequate coverage against potential liabilities. However, we do not maintain insurance for environmental liability or toxic tort claims that may be asserted against us.

In addition, we may incur substantial costs in order to comply with current or future environmental, health and safety laws and regulations. Environmental laws and regulations may impair our research, development or production efforts. In addition, failure to comply with these laws and regulations may result in substantial fines, penalties or other sanctions.

We are subject to a variety of privacy, data protection, and cybersecurity laws, rules, regulations, policies, industry standards and contractual obligations, and our failure to comply with them could harm our business.

We maintain and otherwise process a large quantity of sensitive information, including confidential business and personal information in connection with the conduct of our clinical trials and related to our employees and others, and we are subject to laws and regulations governing the privacy and security of such information. In the United States, numerous federal and state privacy and cybersecurity laws and regulations govern the collection, use, disclosure and protection of personal information, including federal and state health information privacy laws, federal and state security breach notification laws and federal and state consumer protection laws. The legislative and regulatory landscape for privacy, data protection and cybersecurity continues to evolve, and there has been an increasing focus on privacy, data protection and cybersecurity issues, which may affect our business and is expected to increase our compliance costs and exposure to liability. In the United States, numerous federal and state laws and regulations could apply to our operations or the operations of our partners, including state and federal data breach notification laws, state health information privacy and cybersecurity laws and federal and state consumer protection laws and regulations that govern the collection, use, disclosure and protection of health-related and other personal information. Among these regulations are: Section 5 of the Federal Trade Commission Act, which prohibits unfair or deceptive commercial practices; new rules adopted by the SEC in July 2023, which require public companies to disclose material cybersecurity incidents they experience and to disclose on an annual basis material information regarding their cybersecurity risk management, strategy, and governance; and the HIPAA, as amended by HITECH, and the regulations promulgated thereunder.

We may obtain health and other data from third parties, including research institutions from which we obtain clinical trial data, that are subject to privacy and security requirements under HIPAA, and depending on the facts and circumstances, we could be subject to significant penalties if we obtain, use or disclose individually identifiable health information in a manner that is not authorized or permitted by HIPAA.

In the European Economic Area, or the EEA, and the United Kingdom, or the UK, the collection, use, disclosure, transfer or other processing of personal data, including clinical trial data, of individuals is governed by the General Data Protection Regulation, or European Union GDPR (with regard to the EEA), and UK GDPR (with regard to the UK), as well as applicable national data protection legislation and requirements. In this document, “GDPR” refers to both the European Union GDPR and the UK GDPR, unless specified otherwise. The GDPR is wide ranging in scope and imposes numerous requirements on companies that process personal data, including requirements relating to processing health and other sensitive data, obtaining consent of the individuals to whom the personal data relates, providing information to individuals regarding data processing activities, implementing safeguards to protect the security and confidentiality of personal data, providing notification of data breaches, and taking certain measures when engaging third-party processors. The GDPR imposes substantial fines for breaches and violations (up to the greater of €20 million (£17.5 million for the UK) or 4% of our consolidated annual worldwide gross revenue), and confers a private right of action on data subjects and consumer associations to lodge complaints with supervisory authorities, seek judicial remedies and obtain compensation for damages resulting from violations of the GDPR.

The GDPR also includes restrictions on cross-border data transfers of personal data to countries outside the EEA and the UK that are not considered by the European Commission or UK government as providing “adequate” protection to personal data, or third countries, including the United States, unless a valid GDPR transfer mechanism (for example, the European Commission approved Standard Contractual Clauses, or SCCs, and the UK International Data Transfer Agreement/Addendum, or UK IDTA) has been put in place. Where relying on the SCCs or UK IDTA for data transfers, we may also be required to carry out transfer impact assessments to assess whether the recipient is subject to local laws which allow public authority access to personal data. The international transfer obligations under the EEA and UK data protection regimes require significant effort and cost, and may result in us needing to make strategic considerations around where EEA and UK personal data is transferred and which service providers we can utilize for processing EEA and UK personal data.

The UK government also introduced a Data Protection and Digital Information Bill, or the UK Bill, into the UK legislative process. The aim of the UK Bill is to reform the UK’s data protection regime following Brexit. If passed, the final version of the UK Bill may reduce the similarities between the UK and EEA data protection regime and threaten the European Commission's determination that the UK provides "adequate" protection to personal data. The European Commission’s adequacy determination for the UK is subject to renewal in 2025, with the European Commission proposing to change the determination date to December 27, 2025. The UK’s proposal to modify its data protection regime may impact this adequacy determination. Any loss by the UK of its adequacy determination by the European Commission may lead to additional compliance costs and could increase our overall risk. The respective provisions and enforcement of the European Union GDPR and UK GDPR may further diverge in the future and create additional regulatory challenges and uncertainties.

Compliance with these and any other applicable privacy, data protection and cybersecurity laws and regulations is a rigorous and time-intensive process, and we may be required to put in place additional mechanisms ensuring compliance with new and evolving laws and regulations. Further, many privacy, data protection, and cybersecurity regimes are evolving and are inconsistent across jurisdictions. If we fail, or are alleged to fail, to comply with any such laws or regulations, we may face regulatory inquiries, investigations, and other proceedings, private claims and litigation, and significant fines and penalties that could adversely affect our business, financial condition and results of operations. In addition, states are constantly adopting new laws or amending existing laws, requiring attention to frequently changing regulatory requirements. For example, California enacted the California Consumer Privacy Act, or CCPA, which took effect on January 1, 2020, became enforceable on July 1, 2020 and has been dubbed the first “GDPR-like” law in the United States. The CCPA gives California residents expanded rights to access and delete their personal information, opt out of certain personal information sharing and receive detailed information about how their personal information is used by requiring covered companies to provide new disclosures to California consumers (as that term is broadly defined) and provide such consumers new ways to opt out of certain sales of personal information. The CCPA provides for civil penalties for violations, as well as a private right of action for data breaches that is expected to increase data breach litigation. Further, the California Privacy Rights Act, or CPRA, which became effective as of January 1, 2023, amended the CCPA and imposes additional privacy obligations on companies doing business in California, including additional consumer rights processes, limitations on data uses, new audit requirements for higher risk data and opt outs for certain uses of sensitive data. The amendments introduced by the CPRA also created a new California Privacy Protection Agency to implement and enforce this legislation, and it is anticipated that this development could result in increased privacy and information security enforcement. Although the CCPA, as amended by the CPRA, currently exempts certain health-related information, including clinical trial data, the CCPA may increase our compliance costs and potential liability if we expand our operations into California. Similar broad consumer privacy laws have been enacted in Colorado, Connecticut, Delaware, Florida, Indiana, Iowa, Kentucky, Maryland, Minnesota, Montana, Nebraska, New Hampshire, New Jersey, Oregon, Rhode Island, Tennessee, Texas, Utah and Virginia and have been proposed in numerous other states and at the federal level. If passed, these bills may provide for various requirements that would make compliance challenging, particularly in light of certain conflicting and otherwise various requirements in the state privacy laws that have been enacted.

In addition to these consumer privacy laws, the state of Washington has enacted health-focused privacy legislation, the My Health, My Data Act, which became effective in March 2024. This law imposes strict requirements on the collection, use and processing of certain health-related information that is not subject to HIPAA. This law also provides for a private right of action. Other states are considering bills with similar requirements. The Washington law and, if passed, the other state bills, will add additional complexity to our compliance obligations.

With the GDPR, CCPA and other laws, regulations and other obligations relating to privacy and data protection imposing new and relatively burdensome obligations, and with substantial uncertainty over the interpretation and application of these and other obligations, we may face challenges in addressing their requirements and making necessary changes to our policies and practices and may incur significant costs and expenses in an effort to do so. We do not currently have formal data privacy policies and procedures in place and have not completed formal assessments of whether we are in compliance with all applicable data privacy laws and regulations. It is possible that both existing and new laws, regulations, and other actual or asserted obligations to which we are or may be subject may be interpreted and applied in manners inconsistent with our existing or future privacy, data protection and cybersecurity practices. Any failure or perceived failure by us to comply with our current or future obligations relating to privacy, data protection or cybersecurity, or any actual or perceived failure by any third party with which we work, such as third-party CMOs, CROs, manufacturers, contractors, consultants, collaborators, vendors, or service providers, to comply with our applicable policies or other applicable obligations, may result in governmental investigations, enforcement actions, or other proceedings, litigation, claims, or public statements against us and could result in significant liability, cause harm to our brand and reputation, and otherwise materially and adversely affect our reputation and business.

We may be subject to various governmental export control and trade sanctions laws and regulations that could impair our ability to compete in international markets or subject us to liability if we violate these controls.

Our product candidates may be subject to export control and import laws and regulations, including the U.S. Export Administration Regulations administered by the U.S. Department of Commerce and U.S. Customs laws and regulations and our product candidates and activities may be subject to various economic and trade sanctions regulations administered by the U.S. Treasury Department’s Office of Foreign Assets Controls, or collectively, Trade Controls. As such, a license may be required to export or re-export our product candidate, or provide related services, to certain countries and end-users, and for certain end-uses. The process for obtaining necessary licenses may be time-consuming or unsuccessful, potentially causing delays in sales or losses of sales opportunities and these licenses may not be issued. Compliance with applicable regulatory requirements regarding the export or import of our product candidates may create delays in the introduction of our product candidates in international markets or, in some cases, prevent the export of our product candidates to some countries altogether. Furthermore, U.S. export control laws and economic sanctions prohibit the shipment of certain product candidates and services to countries, territories, governments and persons targeted by U.S. sanctions.

Trade Controls are complex and dynamic regimes and monitoring and ensuring compliance can be challenging. Although we have procedures in place designed to ensure our compliance with Trade Controls, any failure to comply could subject us to both civil and criminal penalties, including substantial fines, possible incarceration of responsible individuals for willful violations, possible loss of our export or import privileges, and reputational harm. Although we have no knowledge that our activities have resulted in violations of Trade Controls, there is no certainty that all of our employees, agents, suppliers, manufacturers, contractors or collaborators, or those of our affiliates, will comply with all applicable export and import control and sanctions laws and regulations, particularly given the high level of complexity of these laws. Any failure by us or our partners to comply with applicable laws and regulations could have negative consequences for us, including reputational harm, government investigations, penalties, fines, settlements, investigations, criminal sanctions against us, our officers, or our employees, the closing down of facilities, including those of our suppliers and manufacturers, requirements to obtain export licenses, cessation of business activities in sanctioned countries, implementation of additional compliance programs, and prohibitions on the conduct of our business.

We are subject to U.S. and certain foreign anti-corruption laws and regulations. We could face liability and other serious consequences for violations.

We are subject to anti-corruption laws and regulations, including the FCPA, the U.S. domestic bribery statute contained in 18 U.S.C. § 201, the U.S. Travel Act and will be subject to local and national anti-bribery laws in the countries in which we may conduct activities in the future. Anti-corruption laws are interpreted broadly and generally prohibit companies and their employees, agents, representatives, contractors and other third-party intermediaries from offering, promising, giving, or authorizing others to give anything of value, either directly or indirectly through third parties, to any person in the public or private sector to obtain or retain business. The FCPA also requires public companies to make and keep books and records that accurately and fairly reflect the transactions of the corporation and to devise and maintain an adequate system of internal accounting controls.

Our business is heavily regulated and therefore involves significant interaction with public officials, including officials of non-United States governments. Additionally, in many other countries, the healthcare providers who prescribe pharmaceuticals are employed by their government, and therefore will be considered foreign officials for purposes of the FCPA. We also expect to rely on third parties for research, preclinical studies and clinical trials and/or to obtain necessary permits, licenses, patent registrations and other marketing approvals on our behalf outside of the United States. We can be held liable for the corrupt or other illegal activities of our employees, agents, representatives, CROs, contractors and other third-party intermediaries, even if we do not explicitly authorize or have actual knowledge of such activities.

There is no certainty that all of our employees, agents, representatives, contractors or third-party intermediaries will comply with all applicable anti-corruption laws. Allegations concerning or violations of these laws and regulations could result in whistleblower complaints, fines, settlements, investigations, criminal or civil sanctions, adverse media coverage or suspension or debarment from government contracts, all of which could damage our reputation, our brand, our international expansion efforts, our ability to attract and retain employees, and our business, prospects, operating results and financial condition. Responding to any investigation or action will likely result in a materially significant diversion of management’s attention and resources and significant defense costs and other professional fees.

Risks related to employee matters and managing our growth

Our future success depends on our ability to attract and retain key executives and advisors and to attract, retain and motivate qualified personnel.

We are highly dependent on the management, development, clinical, financial and business development expertise of our executive officers, particularly R. Nolan Townsend, our Chief Executive Officer and a member of our board of directors, Eric Adler, M.D., our Chief Medical Officer and Head of Research, Jose Manuel Otero, our Chief Technical Officer, Louis Tamayo, our Chief Financial Officer, Jenny R. Robertson, our Chief Legal Officer, Sandi See Tai, M.D., our Chief Development Officer, as well as on the scientific expertise of our founder, Ronald G. Crystal, M.D., Professor and Chairman of Weill Cornell Medicine’s Department of Genetic Medicine. Each of our executive officers may currently terminate their employment with us at any time and we do not have an employment contract with Dr. Crystal. We do not maintain “key person” insurance for any of our executives or employees.

Recruiting and retaining qualified executives, scientists and clinical personnel and, if we progress the development of our product pipeline toward scaling up for commercialization, manufacturing and sales and marketing personnel, will also be critical to our success. The loss of the services of our executive officers or other key employees, or our inability to recruit certain executives, could impede the achievement of our development and commercialization objectives and seriously harm our ability to successfully implement our business strategy. Furthermore, recruiting executive officers, or replacing executive officers and key employees may be difficult and may take an extended period of time because of the limited number of individuals in our industry with the breadth of skills and experience required to successfully develop, gain regulatory approval of and commercialize gene therapy products.

Competition to hire from this limited pool is intense, and we have experienced and may continue to experience challenges filling certain executive roles. We may be unable to hire, train, retain or motivate key personnel on acceptable terms given the competition among numerous pharmaceutical and biotechnology companies for similar personnel. We also experience competition for the hiring of scientific and clinical personnel from universities and research institutions. In addition, we rely on consultants and advisors, including scientific and clinical advisors, to assist us in formulating our development and commercialization strategy. Our consultants and advisors may be employed by employers other than us and may have commitments under consulting or advisory contracts with other entities that may limit their availability to us. If we are unable to continue to attract and retain high quality personnel, our ability to pursue our growth strategy will be limited.

We expect to expand our clinical development, manufacturing and regulatory capabilities and potentially implement sales, marketing and distribution capabilities, and as a result, we may encounter difficulties in managing our growth, which could disrupt our operations.

As of September 30, 2025, we had 61 full-time employees. As our development progresses, we expect to experience significant growth in the number of our employees and the scope of our operations, particularly in the areas of clinical product development, regulatory affairs and, if any of our product candidates receives marketing approval, sales, marketing and distribution. To manage our anticipated future growth, we must continue to implement and improve our managerial, operational and financial systems, expand our facilities and continue to recruit and train additional qualified personnel. Due to our limited financial resources and the limited experience of our management team in managing a company with such anticipated growth, we may not be able to effectively manage the expansion of our operations or recruit and train additional qualified personnel. Our choice to focus on multiple therapeutic areas may negatively affect our ability to develop adequately the specialized capability and expertise necessary for operations. The expansion of our operations may lead to significant costs and may divert our management and business development resources. Any inability to manage growth could delay the execution of our business plans or disrupt our operations.

Our employees, independent contractors, consultants, collaborators, principal investigators, CROs, suppliers and vendors may be improperly classified and may engage in misconduct or other improper activities, including non-compliance with regulatory standards and requirements.

We endeavor to properly classify our employees as exempt or non-exempt with respect to wage and hour laws (including, but not limited to, for purposes of minimum wage, overtime and applicable meal and rest periods), and we monitor and evaluate such classifications. Although there are no current, pending, or threatened claims or investigations against us asserting that any employees have been incorrectly classified as exempt, the possibility nevertheless exists that certain job roles could be deemed to have been incorrectly classified as exempt. In addition, we endeavor to classify our workforce properly, and we monitor and evaluate such classifications. Although there are no current, pending, or threatened claims or investigations against us asserting that any independent contractors have been incorrectly classified, the possibility nevertheless exists that certain contractors could be deemed to be employees.

We are exposed to the risk that our employees, independent contractors, consultants, collaborators, principal investigators, CROs, suppliers and vendors may engage in fraudulent conduct or other illegal activity. Misconduct by these parties could include intentional, reckless and/or negligent conduct that violates FDA regulations, including those laws requiring the reporting of true, complete and accurate information to the FDA, manufacturing standards, federal and state healthcare laws and regulations, and laws that require the true, complete and accurate reporting of financial information or data. In particular, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations intended to prevent fraud, kickbacks, self-dealing and other abusive practices. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs and other business arrangements. Misconduct by these parties could also involve the improper use of individually identifiable information, including, without limitation, information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. Although we have adopted a code of business conduct and ethics, it is not always possible to identify and deter misconduct, and the precautions we take to detect and prevent this activity may not be effective in controlling unknown or unmanaged risks or losses or in protecting us from governmental investigations or other actions or lawsuits stemming from a failure to be in compliance with such laws or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business, including the imposition of significant civil, criminal and administrative penalties, including, without limitation, damages, fines, disgorgement, imprisonment, exclusion from participation in government healthcare programs, such as Medicare and Medicaid, additional reporting requirements and oversight if we become subject to a corporate integrity agreement or similar agreement to resolve allegations of non-compliance with these laws, and the curtailment or restructuring of our operations.

The administrator of the 2023 Plan is authorized to exercise its discretion to reprice stock options and stock appreciation rights, and if a repricing occurs, there may be adverse consequences to our business.

The administrator of the 2023 Plan, which is our compensation committee, is authorized, subject to the consent of any award holder whose award is materially impaired by such action, to reduce the exercise price of a stock option or stock appreciation right; to cancel a stock option or stock appreciation right in exchange for a different award, cash or other consideration; or to take any other action that is treated as a repricing under generally accepted accounting principles, or each such action, a repricing.

We have no current expectation that a repricing will occur. However, if the administrator were to implement a repricing without seeking prior stockholder approval, certain proxy advisory firms and/or institutional investors may express a lack of support for the repricing, and proxy advisory firms may recommend an “against” or “withhold” vote for members of our compensation committee or our board of directors. In addition, if we are required to hold an advisory vote on named executive officer compensation (known as a “say on pay” vote) at the time of, or subsequent to, any such repricing, it is likely, based on their current policies, that proxy advisory firms would issue an “against” recommendation on our say on pay proposal. Defending against negative recommendations with respect to our directors and/or say on pay proposal would require management attention, and could be costly and time-consuming.

If our stockholders agree with proxy advisory firms’ recommendations, we may need to make changes to our compensation and corporate governance practices, and perhaps the composition of our board of directors and its committees, potentially leading to business disruptions and a negative impact on our stock price. Even absent negative reactions from proxy advisory firms and institutional investors, we may be required to recognize a compensation expense and the repricing will require management’s time and attention and the payment of administrative costs and attorney and accounting firm fees. As such, a repricing could cause a negative impact on our stock price, and adverse consequences to our business.

Risks related to ownership of our common stock and our status as a public company

The trading price of the shares of our common stock may be volatile, and purchasers of our common stock could incur substantial losses.

The trading price of our common stock is likely to be highly volatile and could be subject to wide fluctuations in response to various factors, some of which are beyond our control, including limited trading volume. The stock market in general and the market for biopharmaceutical companies in particular have experienced extreme volatility that has often been unrelated to the operating performance of particular companies. As a result of this volatility, investors may not be able to sell their common stock at or above the price paid for the shares. The trading price for our common stock may be influenced by many factors, including those discussed in this “Risk Factors” section and elsewhere in this Quarterly Report on Form 10-Q and:

• the reporting of unfavorable preclinical and clinical results;

• the commencement, enrollment or results of our clinical trials of LX2006, LX2020 or any future clinical trials we may conduct, or changes in the development status of our product candidates;

• any delay in our regulatory filings for LX2006, LX2020 or any other product candidate we may develop, and any adverse development or perceived adverse development with respect to the applicable regulatory authority’s review of such filings, including without limitation the FDA’s issuance of a “refusal to file” letter or a request for additional information;

• adverse results from, delays in or termination of clinical trials;

• adverse regulatory decisions, including failure to receive regulatory approval of our product candidates;

• unanticipated serious safety concerns related to the use of LX2006, LX2020 or any other product candidates;

• changes in financial estimates by us or by any equity research analysts who might cover our stock;

• conditions or trends in our industry;

• changes in the market valuations of similar companies;

• regulatory or legal developments in the U.S. and other countries;

• stock trading price and volume fluctuations of comparable companies and, in particular, those that operate in the biopharmaceutical industry;

• publication of research reports about us or our industry or positive or negative recommendations or withdrawal of research coverage by securities analysts;

• announcements by us or our competitors of significant acquisitions, strategic partnerships or divestitures;

• our relationships with our collaborators;

• announcements of investigations or regulatory scrutiny of our operations or lawsuits filed against us;

• investors’ general perception of our company and our business;

• recruitment or departure of key personnel;

• overall performance of the equity markets;

• trading volume of our common stock;

• disputes or other developments relating to proprietary rights, including patents, litigation matters and our ability to obtain patent protection for our technologies;

• significant lawsuits, including patent or stockholder litigation or employee or independent contractor litigation;

• changes in the structure of healthcare payment systems;

• unfavorable geopolitical and economic conditions; and

• other events or factors, many of which are beyond our control.

The global economy, including credit and financial markets and the banking sector, has experienced extreme volatility and disruptions, including, among other things, severely diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, increases in unemployment rates, supply chain shortages, increases in inflation rates, bank failures, higher interest rates, changing foreign trade policies and uncertainty about economic stability. For example, the ongoing wars in Ukraine and Israel have created volatility in the global capital markets and may have further global economic consequences, including disruptions of the global supply chain and energy markets. Any such volatility and disruptions may have adverse consequences on us or the third parties on whom we rely. In addition, investor concerns regarding the U.S. or international financial systems and governmental stability, including as a result of recent tariffs announcements and increased volatility in the credit and equity markets, may impair our ability to raise additional capital or enter into opportunistic strategic partnerships or acquisitions in a timely manner or on favorable terms, or at all. The deterioration of the equity and credit markets may also make any necessary debt or equity financings more costly or more dilutive. Increased inflation rates can adversely affect us by increasing our costs, including labor and employee benefit costs. In addition, higher inflation and macro turmoil and uncertainty could also adversely affect our buyers and sellers, which could reduce demand for our products. These factors may negatively affect the trading price of our common stock, regardless of our actual operating performance.

In addition, in the past, stockholders have initiated class action lawsuits against pharmaceutical and biotechnology companies following periods of volatility in the trading prices of these companies’ stock. This risk is especially relevant for us because biopharmaceutical companies have experienced significant stock price volatility in recent years. Such litigation, if instituted against us, could cause us to incur substantial costs and divert management’s attention and resources, which could harm our business.

If equity research analysts do not publish research or reports, or publish unfavorable research or reports, about us, our business or our market, our stock price and trading volume could decline.

The trading market for our common stock is influenced by the research and reports that equity research analysts publish about us and our business. As a newly public company, we have only limited research coverage by equity research analysts. Equity research analysts may elect not to provide research coverage of our common stock, and such lack of research coverage may adversely affect the trading price of our common stock. While we currently have equity research analyst coverage, we will not have any control over the analysts or the content and opinions included in their reports. The price of our stock could decline if one or more equity research analysts downgrade our stock or issue other unfavorable commentary or research. If one or more equity research analysts cease coverage of our company or fail to publish reports on us regularly, demand for our stock could decrease, which in turn could cause our stock price or trading volume to decline.

We are an “emerging growth company” and a “smaller reporting company” and, as a result of the reduced disclosure and governance requirements applicable to emerging growth companies and smaller reporting companies, our common stock may be less attractive to investors.

We are an “emerging growth company” as defined in the JOBS Act, and we intend to take advantage of some of the exemptions from reporting requirements that are applicable to other public companies that are not emerging growth companies, including:

• not being required to comply with the auditor attestation requirements in the assessment of our internal control over financial reporting;
• not being required to comply with any requirement that may be adopted by the Public Company Accounting Oversight Board regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements;
• reduced disclosure obligations regarding executive compensation in our periodic reports, proxy statements and registration statements; and
• not being required to hold a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved.

We cannot predict if investors will find our common stock less attractive because we will rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be more volatile. We may take advantage of these reporting exemptions until we are no longer an emerging growth company. We will remain an emerging growth company until the last day of the fiscal year ending after the fifth anniversary of our IPO, or, if earlier, (i) the last day of the fiscal year in which we have total annual gross revenue of at least $1.235 billion, (ii) the date on which we are deemed to be a large accelerated filer, which means the market value of our common stock that is held by non-affiliates exceeds $700 million as of the prior June 30, or (iii) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three-year period.

In addition, we have elected to take advantage of the extended transition period to comply with new or revised accounting standards and to adopt certain of the reduced disclosure requirements available to emerging growth companies. As a result of the accounting standards election, we will not be subject to the same implementation timing for new or revised accounting standards as other public companies that are not emerging growth companies, which may make comparison of our financials to those of other public companies more difficult. As a result of these elections, the information that we provide in this Quarterly Report may be different than the information investors may receive from other public companies in which they hold equity interests. In addition, it is possible that some investors will find our common stock less attractive as a result of these elections, which may result in a less active trading market for our common stock and higher volatility in our trading price.

Even after we no longer qualify as an emerging growth company, we may, under certain circumstances, still qualify as a “smaller reporting company,” which would allow us to take advantage of many of the same exemptions from disclosure requirements, including reduced disclosure obligations regarding executive compensation in our periodic reports and proxy statements.

Because we do not anticipate paying any cash dividends on our common stock in the foreseeable future, capital appreciation, if any, will be your sole source of gains and you may never receive a return on your investment.

You should not rely on an investment in our common stock to provide dividend income. We have not declared or paid cash dividends on our common stock to date. We currently intend to retain our future earnings, if any, to fund the development and growth of our business. As a result, capital appreciation, if any, of our common stock will be your sole source of gain for the foreseeable future. Investors seeking cash dividends should not purchase our common stock.

Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware and the federal district courts of the United States of America will be the exclusive forums for substantially all disputes between us and our stockholders, which could limit our stockholders’ ability to obtain a favorable judicial forum for disputes with us or our directors, officers or employees.

Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware is the exclusive forum for the following types of actions or proceedings under Delaware statutory or common law:

• any derivative action or proceeding brought on our behalf;
• any action asserting a breach of fiduciary duty;
• any action asserting a claim against us arising under the Delaware General Corporation Law, or DGCL, our amended and restated certificate of incorporation, or our amended and restated bylaws;
• any claim or cause of action seeking to interpret, apply, enforce or determine the validity of our restated certificate or our amended and restated bylaws;
• any claim or cause of action as to which the DGCL confers jurisdiction on the Court of Chancery of the state of Delaware; and
• any action asserting a claim against us that is governed by the internal-affairs doctrine.

This provision would not apply to suits brought to enforce a duty or liability created by the Exchange Act. Furthermore, Section 22 of the Securities Act creates concurrent jurisdiction for federal and state courts over all such Securities Act actions. Accordingly, both state and federal courts have jurisdiction to entertain such claims. To prevent having to litigate claims in multiple jurisdictions and the threat of inconsistent or contrary rulings by different courts, among other considerations, our amended and restated certificate of incorporation further provides that the federal district courts of the United States will be the exclusive forum for resolving any complaint asserting a cause of action arising under the Securities Act. While the Delaware courts have determined that such choice of forum provisions are facially valid, a stockholder may nevertheless seek to bring a claim in a venue other than those designated in the exclusive forum provisions. In such instance, we would expect to vigorously assert the validity and enforceability of the exclusive forum provisions of our amended and restated certificate of incorporation. This may require significant additional costs associated with resolving such action in other jurisdictions and there can be no assurance that the provisions will be enforced by a court in those other jurisdictions.

These exclusive forum provisions may result in increased costs for investors to bring a claim. Further, these exclusive forum provisions may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable for disputes with us or our directors, officers, or other employees, which may discourage lawsuits against us and our directors, officers and other employees. If a court were to find either exclusive forum provision in our amended and restated certificate of incorporation to be inapplicable or unenforceable in an action, we may incur further significant additional costs associated with resolving the dispute in other jurisdictions, all of which could seriously harm our business.

Provisions in our corporate charter documents and under Delaware law could make an acquisition of us, which may be beneficial to our stockholders, more difficult and may prevent attempts by our stockholders to replace or remove our current management.

Provisions in our certificate of incorporation and our bylaws may discourage, delay, or prevent a merger, acquisition, or other change in control of our company that stockholders may consider favorable, including transactions in which you might otherwise receive a premium for your shares. These provisions could also limit the price that investors might be willing to pay in the future for shares of our common stock, thereby depressing the trading price of our common stock. In addition, because our board of directors is responsible for appointing the members of our management team, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for stockholders to replace members of our board of directors. Among other things, these provisions:

• establish a classified board of directors such that only a portion of our directors stand for election at any given annual stockholder meeting;
• allow the authorized number of our directors to be changed from time to time by our shareholders or our board of directors;
• limit the manner in which stockholders can remove directors from our board of directors;
• establish requirements for stockholder proposals that can be acted on at stockholder meetings;
• require that stockholder actions must be effected at a duly called stockholder meeting and allow actions by our stockholders by written consent, with certain requirements;
• limit who may call stockholder meetings; and
• authorize our board of directors to issue preferred stock without stockholder approval, which could be used to institute a “poison pill” that would work to dilute the stock ownership of a potential hostile acquirer, effectively preventing acquisitions that have not been approved by our board of directors.

Moreover, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the DGCL, which prohibits a person who owns in excess of 15% of our outstanding voting stock from merging or combining with us for a period of three years after the date of the transaction in which the person acquired in excess of 15% of our outstanding voting stock, unless the merger or combination is approved in a prescribed manner.

General risks

Unstable market and economic conditions may have serious adverse consequences on our business and financial condition.

The global economy, including credit and financial markets, has experienced extreme volatility and disruptions recently, including, among other things, recent tariff announcements, diminished liquidity and credit availability, declines in consumer confidence, declines in economic growth, supply chain shortages, increases in inflation rates, higher interest rates, and uncertainty about economic stability. The Federal Reserve has raised interest rates multiple times in response to concerns about inflation and it may raise them again. Higher interest rates, coupled with reduced government spending and volatility in financial markets, may increase economic uncertainty and affect consumer spending. Similarly, the ongoing military conflicts in Ukraine and the Middle East and increasing tensions between China and Taiwan have created extreme volatility in the global capital markets and may have further global economic consequences, including disruptions of the global supply chain. Any such volatility and disruptions may adversely affect our business or the third parties on whom we rely. If the equity and credit markets deteriorate, including as a result of new tariffs, political unrest or war, it may make any necessary debt or equity financing more difficult to complete, more costly, and more dilutive. Failure to secure any necessary financing in a timely manner and on favorable terms could have a material adverse effect on our growth strategy, financial performance and share price and could require us to delay or abandon development or commercialization plans. In addition, there is a risk that one or more of our service providers, manufacturers or other partners would not survive or be able to meet their commitments to us under such circumstances, which could directly affect our ability to attain our operating goals on schedule and on budget. We have experienced and may in the future experience disruptions as a result of such macroeconomic conditions, including delays or difficulties in initiating or expanding clinical trials and manufacturing sufficient quantities of materials. Any one or a combination of these events could have a material and adverse effect on our results of operations and financial condition.

If we fail to maintain proper and effective internal controls, our ability to produce accurate financial statements on a timely basis could be impaired.

We are subject to the reporting requirements of the Exchange Act, the Sarbanes-Oxley Act of 2002, or the Sarbanes-Oxley Act, and the rules and regulations of Nasdaq Stock Market. The Sarbanes-Oxley Act requires, among other things, that we maintain effective disclosure controls and procedures and internal control over financial reporting. In addition, Section 404 of the Sarbanes-Oxley Act requires our management and independent registered public accounting firm to report on the effectiveness of our internal control over financial reporting. We are also required to disclose changes made in our internal controls and procedures on a quarterly basis. However, for so long as we remain an emerging growth company as defined in the JOBS Act, we intend to take advantage of certain exemptions from various reporting requirements that are applicable companies that are not emerging growth companies, including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act. Once we are no longer an emerging growth company or, if prior to such date we opt to no longer take advantage of the applicable exemption, we will be required to include an opinion from our independent registered public accounting firm on the effectiveness of our internal control over financial reporting. An independent assessment of the effectiveness of our internal controls over financial reporting could detect problems that our management’s assessment might not.

The requirements of these rules and regulations are difficult, time-consuming and costly, and place significant strain on our personnel, systems and resources. Effective internal controls over financial reporting are necessary for us to provide reliable financial reports and, together with adequate disclosure controls and procedures, are designed to prevent fraud. In order to maintain and improve the effectiveness of our disclosure controls and procedures and internal control over financial reporting, we have expended and anticipate we will continue to expend significant resources, including accounting-related costs, and provide significant management oversight. Any failure to implement required new or improved controls, or difficulties encountered in their implementation could cause us to fail to meet our reporting obligations. In addition, if we are unable to continue to meet these requirements, we may not be able to remain listed on the Nasdaq Global Market.

We may identify weaknesses in our system of internal financial and accounting controls and procedures that could result in a material misstatement of our financial statements. Our internal control over financial reporting will not prevent or detect all errors and all fraud. A control system, no matter how well designed and operated, can provide only reasonable, not absolute, assurance that the control system’s objectives will be met. Because of the inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that misstatements due to error or fraud will not occur or that all control issues and instances of fraud will be detected. If we fail to identify material weaknesses in our internal control over financial reporting, if we are not able to comply with the requirements of Section 404 of the Sarbanes-Oxley Act in a timely manner, or if we are unable to maintain proper and effective internal controls, we may not be able to produce timely and accurate financial statements. If that were to happen, the trading price of our stock could decline and we could be subject to sanctions or investigations by the stock exchange on which our common stock is listed, the Securities and Exchange Commission, or the SEC, or other regulatory authorities.

Our ability to utilize our net operating loss carryforwards and research tax credits to offset future taxable income may be subject to limitations.

As of December 31, 2024, we had approximately $106.4 million of U.S. federal net operating loss carryforwards, or NOLs, $212.7 million of U.S. state and local NOLs, and $10.7 million of federal tax credits. U.S. federal NOLs generated in taxable years beginning after December 31, 2017, do not expire and may be carried forward indefinitely, but the deductibility of such NOLs is limited to no more than 80% of current year taxable income. Our U.S. state and local NOLs begin to expire in 2040 and our federal research tax credits begin to expire in 2040.

In addition, under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, or the Code, if a corporation undergoes an “ownership change,” which is generally defined as a greater than 50% change, by value, in its equity ownership by certain stockholders over a rolling three-year period, the corporation’s ability to use its pre-change NOLs and certain other pre-change tax attributes (such as research tax credits) to offset its post-change taxable income or taxes may be limited. If we undergo an ownership change, and our ability to use our pre-change NOLs and other pre-change tax attributes (such as tax credits) to offset our post-change income or taxes is limited, it may harm our future results of operations by effectively increasing our future tax obligations. U.S. state and local NOLs may be similarly limited. In addition, at the U.S. state and local level, there may be periods during which the use of NOLs is suspended or otherwise limited, which could accelerate or permanently increase U.S. state and local taxes owed.

Irrespective of the above, our ability to utilize our NOLs and research tax credits to offset future taxable income or taxes is conditioned on our attaining profitability and generating taxable income. We do not know if and when we will generate sufficient taxable income to utilize our NOLs and research tax credits.

Changes in tax laws or regulations that are applied adversely to us or our customers may materially harm our business.

New tax laws, statutes, rules, regulations, or ordinances could be enacted at any time. Further, existing tax laws, statutes, rules, regulations, or ordinances could be interpreted differently, changed, repealed, or modified at any time. Any such enactment, interpretation, change, repeal, or modification could adversely affect us, possibly with retroactive effect. For example, the IRA enacted a 15% minimum tax on the adjusted financial statement income of certain large U.S. corporations for taxable years beginning after December 31, 2022, as well as a 1% excise tax on stock repurchases made by public corporations after December 31, 2022. Further, the Tax Cuts and Jobs Act of 2017, or the Tax Act, enacted many significant changes in U.S. federal tax laws, some of which were further modified by the Coronavirus Aid, Relief, and Economic Security Act, or the CARES Act, and may be modified in the future by the current or a future presidential administration. Among other changes, the Tax Act amended the Code to require that certain research and experimental expenditures be capitalized and amortized over five years if incurred in the United States or fifteen years if incurred in foreign jurisdictions for taxable years beginning after December 31, 2021. If the capitalization and amortization requirement is not deferred, repealed, or otherwise modified, it may increase our cash taxes and effective tax rate. In addition, it is uncertain if and to what extent various states will conform to the IRA, the Tax Act, the CARES Act, or any future U.S. federal tax laws. Changes in corporate tax rates, the realization of net deferred tax assets relating to our operations, the taxation of foreign earnings, and the deductibility of expenses could have a material impact on the value of our deferred tax assets, result in significant one-time charges, and increase our future U.S. tax expenses.

Our business and operations would suffer in the event of system failures, cyberattacks or a deficiency in our or our CMOs’, CROs’, manufacturers’, contractors’, consultants’ or collaborators’ cybersecurity.

In the ordinary course of our business, we and third parties with whom we conduct business, including third-party CMOs, CROs, manufacturers, contractors (including sites performing our clinical trials), consultants, and collaborators, collect and store sensitive data, including intellectual property, clinical trial data, proprietary and confidential business information, and personal data and personal information of our clinical trial subjects, employees, and others. The secure maintenance, transmission, and other processing of this information is critical to our operations.

Despite the implementation of security measures, our internal systems, as well as those of third parties on which we rely, are vulnerable to damage from, among other things, computer viruses, ransomware and other forms of malware, unauthorized access, natural disasters, terrorism, war, telecommunication and electrical failures, system malfunctions, cyberattacks or cyber-intrusions, email attachment compromise, denial of service attacks, phishing attacks, and unauthorized or otherwise improper acts or omissions by persons inside our organization, or persons with access to systems inside our organization. Any such event could lead to the prevention of access to, loss, destruction, alteration, disclosure, or dissemination of, or damage or unauthorized access to or other processing of, our data (including trade secrets or other confidential information, intellectual property, proprietary business information and personal data) or other data that is processed or maintained on our behalf, and cause disruptions to our operations, which could lead to a material disruption of our product candidate development programs. For example, the loss, corruption or unavailability of preclinical study or clinical trial data from completed, ongoing or planned trials could result in delays in our regulatory approval efforts and significantly increase our costs to recover or reproduce the data.

More generally, despite the implementation of security measures in an effort to protect our systems and data, we cannot ensure that our information technology and infrastructure or any of our relevant policies or measures will prevent breakdowns or disruptions of, or breaches or incidents impacting, our systems or those of third parties on which we rely, or other cybersecurity incidents that lead to loss, destruction, unavailability, or unauthorized alteration, dissemination or other processing of, or damage or unauthorized access to, our data, including personal data, our other assets, or other data processed or maintained on our behalf, that could delay clinical development of our product candidates and have a material adverse effect upon our reputation, business, operations or financial condition. To our knowledge, we have not experienced any security breach to date that has had a material impact on our business or operations, but we and the third parties with whom we conduct business have faced, and we anticipate continuing to face, cybersecurity risks, including risks of security breaches and incidents. Risks of security breaches and incidents and other types of system disruptions, particularly through cyberattacks or cyber intrusions, including by hackers, foreign governments, cyber terrorists, and associated actors, have increased generally as the number, intensity, and sophistication of attempted attacks and intrusions from around the world have increased. Geopolitical conflicts and tensions may also increase such risks.

Any security breach or incident resulting in any loss, destruction, unavailability, alteration, disclosure, dissemination, or other processing of, or damage or unauthorized access to, our data, systems or applications, or inappropriate disclosure or other processing of confidential or proprietary information or personal data, , or any other event resulting in unauthorized access to, or disclosure or processing of, such information, or for it to be believed or reported that any of the foregoing has occurred, could lead to us facing regulatory inquiries and proceedings, incurring material legal claims and proceedings, and incurring material damage to our reputation. Any such event could also disrupt our operations, lead to delays in the further development of our product candidates, cause a loss of confidence in us and our ability to conduct clinical trials, compel us to comply with federal and state breach notification laws and foreign law equivalents, subject us to mandatory corrective action, and subject us to material liability under applicable laws, rules, regulations and standards, which could result in significant legal and financial exposure and reputational damage that could have a material adverse effect on our business, operations, and financial condition.

Notifications and follow-up actions related to a security breach or other security incident could impact our reputation and cause us to incur significant costs, including significant legal expenses and remediation costs. We expect to incur significant costs in an effort to detect and prevent security incidents, and we may face increased costs and requirements to expend substantial resources in the event of an actual or perceived security incident. However, we cannot guarantee that we will be able to detect or prevent any such incidents, or that we can remediate any such incidents in an effective or timely manner. Our efforts to improve security and protect data from compromise may also identify previously undiscovered instances of data breaches or other cybersecurity incidents. Any security breach or incident resulting in any loss, destruction, or alteration of, damage or unauthorized access to, or unauthorized or otherwise inappropriate disclosure, dissemination, or other processing of, our data, including personal data, or other information that is processed or maintained on our behalf, any significant damage to or disruption of our systems, or any perception that any of these has occurred, could expose us to litigation and governmental investigations and inquiries, lead to delays in further development and commercialization of our product candidates, and subject us to significant fines, penalties and other liabilities.

Our insurance policies may not be adequate to compensate us for the potential losses arising from any failure or other disruption of, security breach of, or incident impacting, our systems or third-party systems where information important to our business operations is stored or otherwise processed, or any other unauthorized disclosure of information. In addition, such insurance may not be available to us in the future on economically reasonable terms, or at all. Further, our insurance may not cover all claims made against us and could have high deductibles in any event, and defending a suit, regardless of its merit, could be costly and divert management attention.

We incur increased costs and demands upon management as a result of being a public company.

As a public company listed in the United States, we incur significant additional legal, accounting and other expenses that we did not incur as a private company, including the cost of director and officer liability insurance. These additional costs could negatively affect our financial results. In addition, changing laws, regulations and standards relating to corporate governance and public disclosure, including regulations implemented by the SEC and the Nasdaq Stock Market, may increase legal and financial compliance costs and make some activities more time-consuming. These laws, regulations and standards are subject to varying interpretations and, as a result, their application in practice may evolve over time as new guidance is provided by regulatory and governing bodies. We intend to invest resources to comply with evolving laws, regulations and standards, and this investment may result in increased general and administrative expenses and a diversion of management’s time and attention from revenue-generating activities to compliance activities. If notwithstanding our efforts to comply with new laws, regulations and standards, we fail to comply, regulatory authorities may initiate legal proceedings against us and our business may be harmed.

Failure to comply with these rules might also make it more difficult for us to obtain some types of insurance, including director and officer liability insurance, and we might be forced to accept reduced policy limits and coverage or incur substantially higher costs to obtain the same or similar coverage. The impact of these events could also make it more difficult for us to attract and retain qualified persons to serve on our board of directors, on committees of our board of directors, or as members of senior management.

Our disclosure controls and procedures may not prevent or detect all errors or acts of fraud.

We are subject to certain reporting requirements of the Exchange Act. Our disclosure controls and procedures are designed to reasonably assure that information required to be disclosed by us in reports we file or submit under the Exchange Act is accumulated and communicated to management, recorded, processed, summarized, and reported within the time periods specified in the rules and forms of the SEC. We believe that any disclosure controls and procedures or internal controls and procedures, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met.

These inherent limitations include the realities that judgments in decision-making can be faulty, and that breakdowns can occur because of simple error or mistake. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or by an unauthorized override of the controls. Accordingly, because of the inherent limitations in our control system, misstatements or insufficient disclosures due to error or fraud may occur and not be detected.

Item 2. Unregistered Sales of Equity Securities and Use of Proceeds.

Recent Sales of Unregistered Securities; Use of Proceeds

We did not issue any unregistered equity securities during the three months ended September 30, 2025.

Purchases of Equity Securities by the Issuer

None.

Item 3. Defaults Upon Senior Securities.

None.

Item 4. Mine Safety Disclosures.

Not Applicable.

Item 5. Other Information.

Adoption of Inducement Plan

On November 4, 2025, our board of directors adopted the Lexeo Therapeutics, Inc. 2025 Inducement Equity Incentive Plan, or the Inducement Plan, and, subject to the adjustment provisions of the Inducement Plan, reserved 2,000,000 shares of our common stock for issuance pursuant to equity awards granted under the Inducement Plan.

The Inducement Plan was adopted without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq Listing Rules. The Inducement Plan provides for the grant of equity-based awards, including nonstatutory stock options, stock appreciation rights, restricted stock, restricted stock units, performance awards and other awards, and its terms are substantially similar to our 2023 Equity Incentive Plan, including with respect to treatment of equity awards in the event of a “Corporate Transaction” as defined under the Inducement Plan, but with such other terms and conditions intended to comply with the Nasdaq inducement award exception.

In accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules, awards under the Inducement Plan may only be made to individuals not previously employees or non-employee directors of the Company (or following such individuals’ bona fide period of non-employment with the Company), as an inducement material to the individuals’ entry into employment with the Company.

A copy of the Inducement Plan and related form agreements under the Inducement Plan are attached as Exhibit 10.5 hereto and incorporated by reference herein. The above description of the Inducement Plan does not purport to be complete and is qualified in its entirety by reference to such exhibit.

Item 6. Exhibits.

The following exhibits are filed as part of this report:

Exhibit<br><br>Number	Description	Form	File No.	Number	Filing Date
3.1	Amended and Restated Certificate of Incorporation of the Registrant (as amended and currently in effect)	8-K	001-41855	3.1	November 7, 2023
3.2	Amended and Restated Bylaws of the Registrant (as amended and currently in effect)	8-K	001-41855	3.2	November 7, 2023
4.1	Form of Pre-Funded Warrant	8-K	001-41855	4.1	October 17, 2025
10.1	Form of Securities Purchase Agreement dated, October 16, 2025, by and among the Company and the Purchaser	8-K	001-41855	10.1	October 17, 2025
10.2	Form of Registration Rights Agreement dated, October 16, 2025, by and among the Company and the Purchaser	8-K	001-41855	10.2	October 17, 2025
10.3*+	Employment Agreement, as amended on September 14, 2025, by and between the Company and R. Nolan Townsend
10.4*+	Employment Agreement, as amended on September 14, 2025, by and between the Company and Jose Manuel Otero
10.5*+	2025 Inducement Equity Incentive Plan and related form agreements
10.6*+	Employment Agreement, as amended on September 14, 2025, by and between the Company and Louis Tamayo
10.7*+	Transition and Separation Agreement, by and between the Company and Kyle Rasbach, effective August 13, 2025
10.8*†	Amendment No. 4, effective March 5, 2025, to the First License Agreement, dated May 28, 2020, by and between LEXEO Therapeutics, LLC and Cornell University
10.9*†	Amendment No. 3, effective April 1, 2024, to the Second License Agreement, dated May 28, 2020, by and between LEXEO Therapeutics, LLC and Cornell University
10.10*†	Amendment No. 1, effective August 8, 2024 to the License Agreement, dated October 4, 2021, by and between LEXEO Therapeutics, Inc. and the Regents of the University of California
10.11*†	Amendment No. 2, effective May 28, 2025 to the License Agreement, dated October 4, 2021, by and between LEXEO Therapeutics, Inc. and the Regents of the University of California
10.12*†	Amendment No. 1, effective June 4, 2025, to the License Agreement, dated August 6, 2020, by and between Stelios Therapeutics, Inc. and the Regents of the University of California
10.13*†	Amendment No. 1, effective May 30, 2025, to the License Agreement, dated April 23, 2020, by and between Stelios Therapeutics, Inc. (as successor-in-interest to ARVC Therapeutics, Inc.) and the Regents of the University of California
31.1*	Certification of Principal Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
---	---
31.2*	Certification of Principal Financial and Accounting Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32.1*#	Certification of Principal Executive Officer and Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
32.2*#	Certification of Principal Financial and Accounting Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS	Inline XBRL Instance Document-the Instance Document does not appear in the Interactive Data File because XBRL tags are embedded within the Inline XBRL document.
101.SCH	Inline XBRL Taxonomy Extension Schema Document
101.CAL	Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF	Inline XBRL Taxonomy Extension Definition Linkbase Document
101.LAB	Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE	Inline XBRL Taxonomy Extension Presentation Linkbase Document
104	Cover Page Interactive Data File (formatted as inline XBRL with applicable taxonomy extension information contained in Exhibits 101)

* Filed herewith.

• Indicates management contract or compensatory plan.

† Portions of this exhibit (indicated by [***]) have been omitted because the registrant has determined that the information is both not material and is the type that the Registrant treats as private or confidential.

The information in Exhibits 32.1 and 32.2 shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act or the Exchange Act (including this Quarterly Report), unless the Registrant specifically incorporates the foregoing information into those documents by reference.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	LEXEO THERAPEUTICS, INC.
November 5, 2025	By:	/s/ R. Nolan Townsend
		R. Nolan Townsend
		Chief Executive Officer and Director<br>(Principal Executive Officer)
November 5, 2025	By:	/s/ Louis Tamayo
---	---	---
		Louis Tamayo
		Chief Financial Officer<br><br>(Principal Financial and Accounting Officer)

EX-10.3

Exhibit 10.3

EMPLOYMENT AGREEMENT

for

R. NOLAN TOWNSEND

This Employment Agreement (the “Agreement”) is made between Lexeo Therapeutics, Inc. (the “Company”) and R. Nolan Townsend (the “Executive”) (collectively, the “Parties”).

WHEREAS, the Company desires for Executive to provide services to the Company, and wishes to provide Executive with certain compensation and benefits in return for such employment services; and

WHEREAS, Executive wishes to be employed by the Company and to provide personal services to the Company in return for certain compensation and benefits;

NOW, THEREFORE, in consideration of the mutual promises and covenants contained herein and for other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Parties hereto agree as follows:

1. Employment by the Company.

1.1 Position. On or about January 1, 2020, Executive commenced employment with the Company as the Company’s Chief Executive Officer. The Company intends for the Executive to continue serving as the Company’s Chief Executive Officer on the terms and conditions set forth in this Agreement, which shall take effect on October 1, 2023. During the term of Executive’s employment with the Company, Executive will devote Executive’s best efforts and substantially all of Executive’s business time and attention to the business of the Company, except for approved time off permitted by the Company’s general employment policies.

1.2 Duties and Location. Executive shall perform such duties incident to the position(s) held by Executive, including without limitation such duties and responsibilities as may be assigned to Executive by the Board of Directors (the “Board”), to whom Executive will report. Executive’s principal place of employment shall be the Company’s New York City office, but Executive will be permitted to work remotely from home or from other business locations relevant to the execution of his duties and responsibilities. The Company may modify Executive’s job title and duties as it deems necessary and appropriate in light of the Company’s needs and interests from time to time.

1.3 Policies and Procedures. The employment relationship between the Parties shall be governed by the general employment policies and practices of the Company, except that when the terms of this Agreement differ from or are in conflict with the Company’s general employment policies or practices, this Agreement shall control.

1.4 Indemnification. The Executive shall be provided indemnification coverage under the Company’s D&O liability insurance policies to the same extent as directors and other executive officers of the Company.

2. Compensation.

2.1 Salary. For services to be rendered hereunder, Executive shall receive a base salary at the rate of Five Hundred Seventy-Five Thousand Dollars ($575,000) per year (the “Base Salary”), subject to standard payroll deductions and withholdings and payable in accordance with the Company’s regular payroll schedule. The Base Salary is subject to periodic review and modification by the Board (or the Compensation Committee of the Board), from time to time, at its sole discretion.

2.2 Annual Cash Bonus. Executive will be eligible for an annual discretionary cash bonus of up to Fifty-Five Percent (55%) of Executive’s Base Salary (the “Annual Bonus”). Whether Executive receives an Annual Bonus for any given year, and the amount of any such Annual Bonus, will be determined by the Board (or the Compensation Committee of the Board) in its sole discretion based upon the Company’s performance and Executive’s achievement of individual objectives and milestones to be determined on an annual basis. Any Annual Bonus that is awarded will be paid within the first ninety (90) days of the calendar year following the applicable bonus year. Executive will not be eligible for, and will not earn, any Annual Bonus if Executive’s employment terminates for any reason, or if Executive or the Company has given notice of the termination of Executive’s employment, before the payment date.

3. Standard Company Benefits. Executive shall be entitled to participate in all employee benefit programs for which Executive is eligible under the terms and conditions of the benefit plans that may be in effect from time to time and provided by the Company to its employees, subject to the eligibility criteria, rules, plan provisions and regulations applicable to such plans, except to the extent that participation in such plans or programs would result in duplication of benefits provided hereunder. The Company reserves the right to cancel or change the benefit plans or programs it offers to its employees at any time, in its sole discretion.

4. Expenses. The Company will reimburse Executive for reasonable travel, entertainment or other expenses incurred by Executive in furtherance or in connection with the performance of Executive’s duties hereunder, subject to, and in accordance with, the Company’s expense reimbursement policy as in effect from time to time.

5. Termination of Employment; Severance

5.1 At-Will Employment. Executive’s employment relationship is at-will. Either Executive or the Company may terminate the employment relationship at any time, with or without cause or advance notice.

5.2 Termination Based on Death or Disability. In the event of the Executive’s death, the Executive’s employment with the Company shall terminate automatically. The Company, in its discretion, shall have the right to terminate the Executive’s employment because of the Executive’s Disability during the Employment Period, subject to applicable law. For purposes of this Agreement, “Disability” means that the Executive has been unable, for 60 consecutive days, or for any period aggregating 90 business days in any consecutive 180 day period, as the case may be, to perform a substantial portion of the Executive’s duties under this Agreement, as a result of physical or mental impairment, illness or injury, as determined by a medical doctor reasonably selected by the Company and approved by the Executive, such approval not to be unreasonably withheld, delayed or conditioned. Such determination shall be deemed to be conclusive for all purposes of this Section 5.2. In connection with the foregoing, the Executive shall cooperate with such medical doctor, including without limitation, by submitting to such medical tests and examinations as may be requested by the medical doctor. A termination of the Executive’s employment by the Company for Disability shall be communicated to the Executive by written notice upon the expiration of the applicable period and shall be effective on the 30th day after receipt of such notice by the Executive (the “Disability Effective Date”), unless the Executive returns to satisfactory full-time performance of the Executive’s previous duties before the Disability Effective Date. In the event the Executive’s employment is terminated due to death or Disability, the Company shall have no further obligations to the Executive hereunder, except the Company shall pay to the Executive (or, in the event of death, to the Executive’s estate) any (i) Base Salary earned or payable but unpaid to the Executive through the Date of Termination, (ii) reimbursable business expenses incurred but unpaid through the Date of Termination (subject to Company’s applicable expense policies, including submission of all required documentation), (iii) any Annual Bonus earned in the calendar year immediately preceding the calendar year of the Date of Termination to the extent that such Annual Bonus is unpaid as of the Date of Termination, to be paid at the same time as if no such termination occurred, (iv) payment for any accrued by unused vacation time from the year of the Date of Termination , and (v) any other amounts or benefits required by applicable law.

5.3 Termination Without Cause; Resignation for Good Reason.

(i) The Company may terminate Executive’s employment with the Company at any time without Cause (as defined below). Further, Executive may resign at any time for Good Reason (as defined below).

(ii) In the event Executive’s employment with the Company is terminated by the Company without Cause, or Executive resigns for Good Reason, then provided such termination constitutes a “separation from service” (as defined under Treasury Regulation Section 1.409A-1(h), without regard to any alternative definition thereunder, a “Separation from Service”), and provided that Executive remains in compliance with the terms of this Agreement, the Company shall provide Executive with the following severance benefits:

(a) The Company shall pay Executive, as severance, fifteen (15) months of Executive’s base salary in effect as of the date of Executive’s employment termination, subject to standard payroll deductions and withholdings (the “Severance”). The Severance will be paid in a single lump sum on or about the Company’s first regular payroll date following the 60th day after Executive’s Separation from Service.

(b) Provided Executive timely elects continued coverage under COBRA, the Company shall pay Executive’s COBRA premiums to continue Executive’s coverage (including coverage for eligible dependents, if applicable) (“COBRA Premiums”) through the period (the “COBRA Premium Period”) starting on Executive’s Separation from Service and ending on the earliest to occur of: (i) fifteen (15) months following Executive’s Separation from Service; (ii) the date Executive becomes eligible for group health insurance coverage through a new employer; or (iii) the date Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination. In the event Executive becomes covered under another employer’s group health plan or otherwise ceases to be eligible for COBRA during the COBRA Premium Period, Executive must immediately notify the Company of such event. Notwithstanding the foregoing, if the Company determines, in its sole discretion, that it cannot pay the COBRA Premiums without a substantial risk of violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company instead shall pay to Executive, on the first day of each calendar month, a fully taxable cash payment equal to the applicable COBRA premiums for that month (including premiums for Executive and Executive’s eligible dependents who have elected and remain enrolled in such COBRA coverage), subject to applicable tax withholdings (such amount, the “Special Cash Payment”), for the remainder of the COBRA Premium Period. Executive may, but is not obligated to, use such Special Cash Payments toward the cost of COBRA premiums.

5.4 Termination for Cause; Resignation Without Good Reason; Death or Disability.

(i) The Company may terminate Executive’s employment with the Company at any time for Cause. Further, Executive may resign at any time without Good Reason. Executive’s employment with the Company may also be terminated due to Executive’s death or disability.

(ii) If Executive resigns without Good Reason, or the Company terminates Executive’s employment for Cause, or upon Executive’s death or disability, then (i) Executive will no longer vest in the Option and any other stock options held by the Executive, (ii) all payments of compensation by the Company to Executive hereunder will terminate immediately (except as to amounts already earned), and (c) Executive will not be entitled to any severance benefits, including (without limitation) the Severance, COBRA Premiums, Special Cash Payments, unless required by law.

5.5 Termination in Connection with Change in Control. If the Company terminates Executive’s employment no more than three (3) months prior to a Change in Control (as defined herein) or within twelve (12) months after a Change in Control, Executive shall be entitled to receive the following severance benefit:

(i) The Company shall pay Executive, as severance, eighteen (18) months of Executive’s base salary in effect as of the date of Executive’s employment termination, subject to standard payroll deductions and withholdings (the “CIC Severance”). The CIC Severance will be paid in equal installments on the Company’s regular payroll schedule over the eighteen (18) month period following Executive’s Separation from Service; provided, however, that no payments will be made prior to the 60th day following Executive’s Separation from Service. On the 60th day following Executive’s Separation from Service, the Company will pay Executive in a lump sum the Severance that Executive would have received on or prior to such date under the standard payroll schedule but for the delay while waiting for the 60th day in compliance with Code Section 409A, with the balance of the Severance being paid as originally scheduled.

(ii) Provided Executive timely elects continued coverage under COBRA, the Company shall pay Executive’s COBRA premiums to continue Executive’s coverage (including coverage for eligible dependents, if applicable) (“CIC COBRA Premiums”) through the period (the “CIC COBRA Premium Period”) starting on Executive’s Separation from Service and ending on the earliest to occur of: (a) eighteen (18) months following Executive’s Separation from Service; (b) the date Executive becomes eligible for group health insurance coverage through a new employer; or (c) the date Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination. In the event Executive becomes covered under another employer’s group health plan or otherwise ceases to be eligible for COBRA during the CIC COBRA Premium Period, Executive must immediately notify the Company of such event. Notwithstanding the foregoing, if the Company determines, in its sole discretion, that it cannot pay the CIC COBRA Premiums without a substantial risk of violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company instead shall pay to Executive, on the first day of each calendar month, a fully taxable cash payment equal to the applicable COBRA premiums for that month (including premiums for Executive and Executive’s eligible dependents who have elected and remain enrolled in such COBRA coverage), subject to applicable tax withholdings (such amount, the “CIC Special Cash Payment”), for the remainder of the CIC COBRA Premium Period. Executive may, but is not obligated to, use such CIC Special Cash Payments toward the cost of COBRA premiums.

(iii) The Company shall pay Executive, as further severance, a lump sum amount equal to one and a half times his full bonus target for the calendar year in which the Change in Control occurs (the “CIC Bonus Payment”), to be paid no later than thirty (30) days following Executive’s Separation from Service.

(iv) The Company shall accelerate the vesting of any shares, options, or other equity grants then unvested and outstanding as of the Executive’s Separation from Service, such that Executive will thereafter be 100% vested in any shares, options, or other equity grants awarded by the Company to Executive during Executive’s employment with the Company (the “Vesting Acceleration”).

6. Conditions to Receipt of Severance, COBRA Premiums, and Special Cash Payments. The receipt of the Severance, CIC Severance, COBRA Premiums, CIC COBRA Premiums, Special Cash Payments, CIC Special Cash Payments, CIC Bonus Payment, and Vesting Acceleration (collectively, the “Severance Benefits”) will be subject to Executive signing and not revoking a separation agreement and release of claims in a form satisfactory to the Company (the “Separation Agreement”) within a time period specified by the Company, in its sole discretion. No Severance Benefits will be paid or provided until the Separation Agreement becomes effective. Executive shall also resign from all positions and terminate any relationships as an employee, advisor, officer or director with the Company and any of its affiliates, each effective on the date of termination.

7. Section 409A. It is intended that all of the severance benefits and other payments payable under this Agreement satisfy, to the greatest extent possible, the exemptions from the application of Code Section 409A provided under Treasury Regulations 1.409A-1(b)(4), 1.409A-1(b)(5) and 1.409A-1(b)(9), and this Agreement will be construed to the greatest extent possible as consistent with those provisions, and to the extent not so exempt, this Agreement (and any definitions hereunder) will be construed in a manner that complies with Section 409A. For purposes of Code Section 409A (including, without limitation, for purposes of Treasury Regulation Section 1.409A-2(b)(2)(iii)), Executive’s right to receive any installment payments under this Agreement (whether severance payments, reimbursements or otherwise) shall be treated as a right to receive a series of separate payments and, accordingly, each installment payment hereunder shall at all times be considered a separate and distinct payment. Notwithstanding any provision to the contrary in this Agreement, if Executive is deemed by the Company at the time of Executive’s Separation from Service to be a “specified employee” for purposes of Code Section 409A(a)(2)(B)(i), and if any of the payments upon Separation from Service set forth herein and/or under any other agreement with the Company are deemed to be “deferred compensation”, then to the extent delayed commencement of any portion of such payments is required in order to avoid a prohibited distribution under Code Section 409A(a)(2)(B)(i) and the related adverse taxation under Section 409A, such payments shall not be provided to Executive prior to the earliest of (i) the expiration of the six-month period measured from the date of Executive’s Separation from Service with the Company, (ii) the date of Executive’s death or (iii) such earlier date as permitted under Section 409A without the imposition of adverse taxation. Upon the first business day following the expiration of such applicable Code Section 409A(a)(2)(B)(i) period, all payments deferred pursuant to this Paragraph shall be paid in a lump sum to Executive, and any remaining payments due shall be paid as otherwise provided herein or in the applicable agreement. No interest shall be due on any amounts so deferred.

8. Definitions.

(i) Cause. For purposes of this Agreement, “Cause” for termination will mean: (a) Executive’s conviction for, or entry of a guilty plea or plea of nolo contendere for, any felony or crime involving dishonesty; (b) Executive’s participation in any fraud against the Company; (c) material breach of Executive’s duties to the Company; (d) persistent unsatisfactory performance of Executive’s job duties after written notice from the Board and a reasonable opportunity to cure (if deemed curable); (e) Executive’s intentional damage to any property of the Company; (f) Executive’s intentional violation of Company policy that causes harm to the Company’s reputation or prospects; (g) Executive’s material breach of any written agreement with the Company; and (h) conduct by Executive involving moral turpitude, corruption, dishonesty, or other conduct that harms the Company’s reputation or prospects.

(ii) Good Reason. For purposes of this Agreement, Executive shall have “Good Reason” for resignation from employment with the Company if any of the following actions are taken by the Company without Executive’s prior written consent: (a) a material reduction in Executive’s base salary, which the parties agree is a reduction of at least 10% of Executive’s base salary (unless pursuant to a salary reduction program applicable generally to the Company’s similarly situated executive employees); (b) a material reduction in Executive’s duties (including responsibilities and/or authorities), provided, however, that a change in job position shall not be deemed a “material reduction” in and of itself unless Executive’s new duties are materially reduced from the prior duties; or (c) relocation of Executive’s principal place of employment to a place that increases Executive’s one-way commute by more than sixty (60) miles as compared to Executive’s then-current principal place of employment immediately prior to such relocation. In order to resign for Good Reason, Executive must provide written notice to the Board within 30 days after the first occurrence of the event giving rise to Good Reason setting forth the basis for Executive’s resignation, allow the Company at least 30 days from receipt of such written notice to cure such event, and if such event is not reasonably cured within such period, Executive must resign from all positions Executive then holds with the Company not later than 90 days after the expiration of the cure period.

(iii) Change in Control. For purposes of this Agreement, “Change in Control” shall have the meaning set forth in the Lexeo Therapeutics, Inc. 2023 Equity Incentive Plan.

9. Proprietary Information Obligations.

9.1 Confidential Information Agreement. As a condition of employment, Executive shall execute and abide by the Company’s standard form of Employee Confidential Information And Inventions Assignment Agreement (the “Confidentiality Agreement”).

9.2 Third-Party Agreements and Information. Executive represents and warrants that Executive’s employment by the Company does not conflict with any prior employment or consulting agreement or other agreement with any third party, and that Executive will perform Executive’s duties to the Company without violating any such agreement. Executive represents and warrants that Executive does not possess confidential information arising out of prior employment, consulting, or other third party relationships, that would be used in connection with Executive’s employment by the Company, except as expressly authorized by that third party. During Executive’s employment by the Company, Executive will use in the performance of Executive’s duties only information which is generally known and used by persons with training and experience comparable to Executive’s own, common knowledge in the industry, otherwise legally in the public domain, or obtained or developed by the Company or by Executive in the course of Executive’s work for the Company. Executive expressly acknowledges that he will not use any confidential or proprietary information of a third-party in connection with the performance of his duties to the Company.

10. Outside Activities During Employment.

10.1 Non-Company Business. Except with the prior written consent of the Board, Executive will not during the term of Executive’s employment with the Company undertake or engage in any other employment, occupation or business enterprise, other than ones in which Executive is a passive investor. In any event, Executive may: (i) engage in civic and not-for-profit activities; (ii) engage in activities in connection with personal investments; (iii) serve, following receiving consent from the Board (which shall not unreasonably be withheld), on board of directors positions for up to two (2) corporations, and (iv) serve as an advisor, or as a member of an advisory board, following receiving consent from the Board (which shall not unreasonably be withheld), on up to two (2) organizations; so long as such activities do not materially interfere with the performance of Executive’s duties hereunder.

10.2 No Adverse Interests. Executive agrees not to acquire, assume or participate in, directly or indirectly, any position, investment or interest known to be adverse or antagonistic to the Company, its business or prospects, financial or otherwise. This does not prohibit the Executive from purchasing any publicly listed securities or funds which hold publicly listed securities.

11. Dispute Resolution. To ensure the timely and economical resolution of disputes that may arise in connection with Executive’s employment with the Company, Executive and the Company agree that any and all disputes, claims, or causes of action arising from or relating to the enforcement, breach, performance, negotiation, execution, or interpretation of this Agreement, the Confidential Information Agreement, or Executive’s employment, or the termination of Executive’s employment, including but not limited to all statutory claims, with the exception of discrimination and harassment claims, will be resolved pursuant to the Federal Arbitration Act, 9 U.S.C. §1-16 (the “FAA”), and to the fullest extent permitted by law, by final, binding and confidential arbitration by a single arbitrator conducted in New York, New York by Judicial Arbitration and Mediation Services Inc. (“JAMS”) under the then applicable JAMS rules appropriate to the relief being sought (the applicable rules are available at the following web addresses: (i) https://www.jamsadr.com/rules-employment-arbitration/ and (ii) https://www.jamsadr.com/rules-comprehensive-arbitration/); provided, however, this arbitration provision not apply to any action or claim that cannot be subject to mandatory arbitration as a matter of law, including, without limitation, claims involving allegations of sexual harassment and discrimination, to the extent such claims are not permitted by applicable law(s) to be submitted to mandatory arbitration and the applicable law(s) are not preempted by the FAA or otherwise invalid (collectively, the “Excluded Claims”). A hard copy of the rules will be provided to Executive upon request. A hard copy of the rules will be provided to Executive upon request. By agreeing to this arbitration procedure, both Executive and the Company waive the right to resolve any such dispute through a trial by jury or judge or administrative proceeding. In addition, all claims, disputes, or causes of action under this section, whether by Executive or the Company, must be brought in an individual capacity, and shall not be brought as a plaintiff (or claimant) or class member in any purported class or representative proceeding, nor joined or consolidated with the claims of any other person or entity. The Arbitrator may not consolidate the claims of more than one person or entity, and may not preside over any form of representative or class proceeding. To the extent that the preceding sentences regarding class claims or proceedings are found to violate applicable law or are otherwise found unenforceable, any claim(s) alleged or brought on behalf of a class shall proceed in a court of law rather than by arbitration. The Company acknowledges that Executive will have the right to be represented by legal counsel at any arbitration proceeding. Questions of whether a claim is subject to arbitration under this Agreement) shall be decided by a federal court in the State of New York. However, procedural questions which grow out of the dispute and bear on the final disposition are matters for the arbitrator. The arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by law; (b) issue a written arbitration decision, to include the arbitrator’s essential findings and conclusions and a statement of the award; and (c) be authorized to award any or all remedies that Executive or the Company would be entitled to seek in a court of law. Executive and the Company shall equally share all JAMS’ arbitration fees. To the extent JAMS does not collect or Executive otherwise does not pay to JAMS an equal share of all JAMS’ arbitration fees for any reason, and the Company pays JAMS Executive’s share, Executive acknowledges and agrees that the Company shall be entitled to recover from Executive half of the JAMS arbitration fees invoiced to the parties (less any amounts Executive paid to JAMS) in a federal or state court of competent jurisdiction. Except as modified in the Confidential Information Agreement, each party is responsible for its own attorneys’ fees. Nothing in this Agreement is intended to prevent either Executive or the Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Any awards or orders in such arbitrations may be entered and enforced as judgments in the federal and state courts of any competent jurisdiction. To the extent a New York federal court determines that any applicable law prohibits mandatory arbitration of Excluded Claims, if Executive intends to bring multiple claims, including one or more Excluded Claims, the Excluded Claim(s) may be publicly filed with a court, while any other claims will remain subject to mandatory arbitration.

12. Section 280G Matters.

12.1 If any payment or benefit Executive will or may receive from the Company or otherwise (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but for this Section, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment provided pursuant to this Agreement (a “Payment”) shall be equal to the Reduced Amount. The “Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax, or (y) the largest portion, up to and including the total, of the Payment, whichever amount (i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state, and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in Executive’s receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction Method”) that results in the greatest economic benefit for Executive. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction Method”).

12.2 Notwithstanding any provision of this Section 12 to the contrary, if the Reduction Method or the Pro Rata Reduction Method would result in any portion of the Payment being subject to taxes pursuant to Section 409A that would not otherwise be subject to taxes pursuant to Section 409A, then the Reduction Method and/or the Pro Rata Reduction Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the greatest economic benefit for Executive as determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without Cause), shall be reduced (or eliminated) before Payments that are not contingent on future events; and (C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A shall be reduced (or eliminated) before Payments that are not deferred compensation within the meaning of Section 409A.

12.3 The Company shall appoint a nationally-recognized accounting, consulting or law firm to make the determinations required by this Section 12. The Company shall bear all expenses with respect to the determinations by such firm required to be made hereunder.

12.4 If Executive receives a Payment for which the Reduced Amount was determined pursuant to clause (x) of and the Internal Revenue Service determines thereafter that some portion of the Payment is subject to the Excise Tax, Executive agrees to promptly return to the Company a sufficient amount of the Payment (after reduction pursuant to clause (x) of Section 12(i)) so that no portion of the remaining Payment is subject to the Excise Tax. For the avoidance of doubt, if the Reduced Amount was determined pursuant to clause (y) of Section 12(i), Executive shall have no obligation to return any portion of the Payment pursuant to the preceding sentence.

13. General Provisions.

13.1 Notices. Any notices provided must be in writing and will be deemed effective upon the earlier of personal delivery (including personal delivery by fax) or the next day after sending by overnight carrier, to the Company at its primary office location and to Executive at the address as listed on the Company payroll.

13.2 Severability. Whenever possible, each provision of this Agreement will be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Agreement is held to be invalid, illegal or unenforceable in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality or unenforceability will not affect any other provision or any other jurisdiction, but this Agreement will be reformed, construed and enforced in such jurisdiction to the extent possible in keeping with the intent of the parties.

13.3 Waiver. Any waiver of any breach of any provisions of this Agreement must be in writing to be effective, and it shall not thereby be deemed to have waived any preceding or succeeding breach of the same or any other provision of this Agreement.

13.4 Complete Agreement. This Agreement, together with the Confidentiality Agreement, constitutes the entire agreement between Executive and the Company with regard to this subject matter and is the complete, final, and exclusive embodiment of the Parties’ agreement with regard to this subject matter. This Agreement supersedes and replaces all previous agreements between the Parties concerning the terms and conditions of Executive’s employment, including but not limited to the Employment Agreement between Executive and Company dated on or about January 1, 2020. This Agreement is entered into without reliance on any promise or representation, written or oral, other than those expressly contained herein, and it supersedes any other such promises, warranties or representations. It is entered into without reliance on any promise or representation other than those expressly contained herein, and it cannot be modified or amended except in a writing signed by a duly authorized officer of the Company.

13.5 Amendments and Waivers. This Agreement cannot be changed, modified or amended, and no provision or requirement hereof may be waived, without the consent in writing of the Executive and the Company. The failure of a party at any time or times to require performance of any provision hereof shall in no manner affect the right of such party at a later time to enforce the same. No waiver by a party of the breach of any term or covenant contained in this Agreement, whether by conduct or otherwise, in any one or more instances, shall be deemed to be, or construed as, a further or continuing waiver of any such breach, or a waiver of the breach of any other term or covenant in this Agreement.

13.6 Counterparts. This Agreement may be executed in separate counterparts, any one of which need not contain signatures of more than one party, but all of which taken together will constitute one and the same Agreement.

13.7 Headings. The headings of the paragraphs hereof are inserted for convenience only and shall not be deemed to constitute a part hereof nor to affect the meaning thereof.

13.8 Successors and Assigns. This Agreement is intended to bind and inure to the benefit of and be enforceable by Executive and the Company, and their respective successors, assigns, heirs, executors and administrators, except that Executive may not assign any of his duties hereunder and he may not assign any of his rights hereunder without the written consent of the Company, which shall not be withheld unreasonably.

13.9 Tax Withholding and Indemnification. All payments and awards contemplated or made pursuant to this Agreement will be subject to withholdings of applicable taxes in compliance with all relevant laws and regulations of all appropriate government authorities. Executive acknowledges and agrees that the Company has neither made any assurances nor any guarantees concerning the tax treatment of any payments or awards contemplated by or made pursuant to this Agreement. Executive has had the opportunity to retain a tax and financial advisor and fully understands the tax and economic consequences of all payments and awards made pursuant to the Agreement.

13.10 Choice of Law. All questions concerning the construction, validity and interpretation of this Agreement will be governed by the laws of the State of New York.

IN WITNESS WHEREOF, the Parties have executed this Agreement on the day and year written below.

LEXEO THERAPEUTICS, INC.:
By:	/s/ Steven Altschuler
	Steven Altschuler
	Chairman of the Board
	Date: September 28, 2023
	R. NOLAN TOWNSEND
By:	/s/ R. Nolan Townsend
	Chief Executive Officer
	Date: September 28, 2023

CORRECTION TO

EMPLOYMENT AGREEMENT

THIS CORRECTION TO EMPLOYMENT AGREEMENT (this “Correction”) corrects the employment agreement made between Lexeo Therapeutics, Inc. (the “Company”) and R. Nolan Townsend (the “Executive”) dated September 28, 2023 (the “Employment Agreement”). This Correction is effective as of the effective date of the Employment Agreement (the “Effective Date”). Capitalized terms used herein but not defined shall have the meanings given to such terms in the Employment Agreement.

WHEREAS, the Company and Executive have agreed to amend Section 5.5 of the Employment Agreement in order to correct the termination provisions in connection with change in control.

NOW, THEREFORE, in consideration of the mutual promises and covenants set forth herein, and other good and valuable consideration, receipt of which is hereby acknowledged, the parties to this Correction hereby agree that the Employment Agreement shall be amended as follows:

• Amendment to Section 5.5. As of the Effective Date, the first paragraph of Section 5.5 of the Employment Agreement is hereby amended and restated as follows:

“5.5 Termination in Connection with Change in Control. If the Company terminates

Executive’s employment without Cause, or Executive resigns for Good Reason, no more than three (3) months prior to a Change in Control (as defined herein) or within twelve (12) months after a Change in Control, Executive shall be entitled to receive the following severance benefit (in lieu of, and not in addition to, the benefits described in Section 5.3):”

• Miscellaneous.
• No Other Amendment. Except as modified by this Correction, the Employment Agreement shall remain in full force and effect in all respects without any modification.
• Subsequent Adjustments to Compensation Terms. Any adjustments to Executive’s compensation terms (including but not limited to base salary and bonus) implemented subsequent to the date of the Employment Agreement will be unaffected by the Correction and will remain in effect notwithstanding this Correction.
• At Will. Nothing in this Correction shall modify the at-will nature of the employment relationship.
• Successors and Assigns. The terms and conditions of this Correction shall inure to the benefit of and be binding upon the respective successors and assigns of the parties. Nothing in this Correction, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and assigns any rights, remedies, obligations, or liabilities under or by reason of this Correction, except as expressly provided in this Correction.
• Arbitration: Choice of Laws. This Correction shall be governed in all respects by the dispute resolution provisions of the Employment Agreement (including, without limitation, provisions regarding mandatory arbitration and governing law).
• Titles and Subtitles. The titles and subtitles used in this Correction are used for convenience only and are not to be considered in construing or interpreting this Correction.
• Counterparts. This Correction may be executed in any number of counterparts, each of which shall be enforceable against the parties that execute such counterparts, and all of which together shall constitute one instrument.

IN WITNESS WHEREOF, the parties hereto have executed this Correction as of the date set forth

above.

Lexeo Therapeutics, Inc.:		Executive:
By:
Signature:	/s/ Jenny R. Robertson	Signature:	/s/ R. Nolan Townsend
Name:	Jenny R. Robertson	Name:	R. Nolan Townsend
Title:	Chief Legal Officer

EX-10.4

Exhibit 10.4

EMPLOYMENT AGREEMENT

for

JOSE MANUEL OTERO, PH.D.

This Employment Agreement (the “Agreement”) is made between Lexeo Therapeutics, Inc. (the “Company”) and Jose Manuel Otero, Ph.D. (the “Executive”) (collectively, the “Parties”).

Whereas, the Company desires for Executive to provide services to the Company, and wishes to provide Executive with certain compensation and benefits in return for such employment services; and

Whereas, Executive wishes to be employed by the Company and to provide personal services to the Company in return for certain compensation and benefits;

Now, Therefore, in consideration of the mutual promises and covenants contained herein and for other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Parties hereto agree as follows:

• Employment by the Company.

Position. Beginning May 20, 2024, Executive shall serve as the Company’s Chief Technical Officer. During the term of Executive’s employment with the Company, Executive will devote Executive’s best efforts and substantially all of Executive’s business time and attention to the business of the Company, except for approved time off permitted by the Company’s general employment policies.

• Duties and Location. Executive shall perform such duties incident to the position(s) held by Executive, including without limitation such duties and responsibilities as may be assigned to Executive by the Chief Executive Officer (“CEO”), to whom Executive will report. Executive shall work in the Company’s New York City office as needed and requested by the Company, and Executive will be permitted to work remotely from his home office in Connecticut when not in the New York City office. The Company reserves the right, at the Board’s discretion, to reasonably require Executive to perform Executive’s duties at places other than Executive’s primary office location from time to time, and to require reasonable business travel. The Company may modify Executive’s job title and duties as it deems necessary and appropriate in light of the Company’s needs and interests from time to time.
• Policies and Procedures. The employment relationship between the Parties shall be governed by the general employment policies and practices of the Company, except that when the terms of this Agreement differ from or are in conflict with the Company’s general employment policies or practices, this Agreement shall control.
• Indemnification. The Executive shall be provided indemnification coverage under the Company’s D&O liability insurance policies to the same extent as directors and other executive officers of the Company.
• Compensation.
• Salary. For services to be rendered hereunder, Executive shall receive a base salary at the rate of Four Hundred Thirty-Five Thousand Dollars ($435,000) per year (the “Base Salary”), subject to standard payroll deductions and withholdings and payable in accordance with the Company’s regular payroll schedule. The Base Salary is subject to periodic review and modification by the CEO and the Board (or the Compensation Committee of the Board), from time to time, at their sole discretion.

Annual Cash Bonus. Executive will be eligible for an annual discretionary cash bonus of up to Forty Percent (40%) of Executive’s Base Salary (the “Annual Bonus”). Whether Executive receives an Annual Bonus for any given year, and the amount of any such Annual Bonus, will be determined by the CEO and the Board (or the Compensation Committee of the Board) in their sole discretion based upon the Company’s performance and Executive’s achievement of individual objectives and milestones to be determined on an annual basis. Any Annual Bonus that is awarded will be paid within the first ninety (90) days of the calendar year following the applicable bonus year. Executive will not be eligible for, and will not earn, any Annual Bonus if Executive’s employment terminates for any reason, or if Executive or the Company has given notice of the termination of Executive’s employment, before the payment date, except as expressly provided for in Section 5.5 herein.

• Equity Awards. Subject to the approval of the Company’s Compensation Committee of the Board of Directors (the “Committee”), you will be granted a mix of equity awards as follows:

• An option to purchase 187,500 shares of the Company’s Common Stock (the “Option”). The Option will vest and become exercisable over 4 years at the rate of 25% of the total number of Option shares on the 1-year anniversary of your start date of employment with the Company and 1/48th of the total number of Option shares on each monthly anniversary thereafter, subject to your continuous service with the Company through each vesting date. The exercise price per share of the Option will be equal to the fair market value per share of the Company’s Common Stock on the date the Option is granted, as determined by the Board in good faith. There is no guarantee that the Internal Revenue Service will agree with this value.

• 31,250 restricted stock units of the Company’s Common Stock (the “RSUs”). The RSUs will vest over a period of approximately 4 years. RSUs for the Company will generally vest on specific dates each quarter for the entire Company. The vesting start date of your RSUs will be the next Company RSU vesting date that occurs after your start date. The RSUs will vest as to 25% of the total number of RSUs on the 1- year anniversary of your RSU vesting start date and 1/16th of the total number of RSU shares on each quarterly date 3-months thereafter, subject to your continuous service with the Company through each vesting date.

• Standard Company Benefits. Executive shall be entitled to participate in all employee benefit programs for which Executive is eligible under the terms and conditions of the benefit plans that may be in effect from time to time and provided by the Company to its employees, subject to the eligibility criteria, rules, plan provisions and regulations applicable to such plans, except to the extent that participation in such plans or programs would result in duplication of benefits provided hereunder. The Company reserves the right to cancel or change the benefit plans or programs it offers to its employees at any time, in its sole discretion.

• Expenses. The Company will reimburse Executive for reasonable travel, entertainment or other expenses incurred by Executive in furtherance or in connection with the performance of Executive’s duties hereunder, subject to, and in accordance with, the Company’s expense reimbursement policy as in effect from time to time.

• Termination of Employment; Severance

• At-Will Employment. Executive’s employment relationship is at-will. Either Executive or the Company may terminate the employment relationship at any time, with or without cause or advance notice.

• Termination Based on Death or Disability. In the event of the Executive’s death, the Executive’s employment with the Company shall terminate automatically. The Company, in its discretion, shall have the right to terminate the Executive’s employment because of the Executive’s Disability during the Employment Period, subject to applicable law. For purposes of this Agreement, “Disability” means that the Executive has been unable, for 60 consecutive days, or for any period aggregating 90 business days in any consecutive 180 day period, as the case may be, to perform a substantial portion of the Executive’s duties under this Agreement, as a result of physical or mental impairment, illness or injury, as determined by a medical doctor reasonably selected by the Company and approved by the Executive, such approval not to be unreasonably withheld, delayed or conditioned. Such determination shall be deemed to be conclusive for all purposes of this Section 5.2. In connection with the foregoing, the Executive shall cooperate with such medical doctor, including without limitation, by submitting to such medical tests and examinations as may be requested by the medical doctor. A termination of the Executive’s employment by the Company for Disability shall be communicated to the Executive by written notice upon the expiration of the applicable period and shall be effective on the 30th day after receipt of such notice by the Executive (the “Disability Effective Date”), unless the Executive returns to satisfactory full-time performance of the Executive’s previous duties before the Disability Effective Date. In the event the Executive’s employment is terminated due to death or Disability, the Company shall have no further obligations to the Executive hereunder, except the Company shall pay to the Executive (or, in the event of death, to the Executive’s estate) any (i) Base Salary earned or payable but unpaid to the Executive through the Date of Termination, (ii) reimbursable business expenses incurred but unpaid through the Date of Termination (subject to Company’s applicable expense policies, including submission of all required documentation), and (iii) any other amounts or benefits required by applicable law.

• Termination Without Cause; Resignation for Good Reason.

• The Company may terminate Executive’s employment with the Company at any time without Cause (as defined below). Further, Executive may resign at any time for Good Reason (as defined below).

• In the event Executive’s employment with the Company is terminated by the Company without Cause, or Executive resigns for Good Reason, then provided such termination constitutes a “separation from service” (as defined under Treasury Regulation Section 1.409A-1(h), without regard to any alternative definition thereunder, a “Separation from Service”), and provided that Executive remains in compliance with the terms of this Agreement, the Company shall provide Executive with the following severance benefits:

• The Company shall pay Executive, as severance, twelve (12) months of Executive’s base salary in effect as of the date of Executive’s employment termination, subject to standard payroll deductions and withholdings (the “Severance”). The Severance will be paid in a single lump sum on or about the Company’s first regular payroll date following the 60th day after Executive’s Separation from Service.

• Provided Executive timely elects continued coverage under COBRA, the Company shall pay Executive’s COBRA premiums to continue Executive’s coverage (including coverage for eligible dependents, if applicable) (“COBRA Premiums”) through the period (the “COBRA Premium Period”) starting on Executive’s Separation from Service and ending on the earliest to occur of: (i) twelve (12) months following Executive’s Separation from Service; (ii) the date Executive becomes eligible for group health insurance coverage through a new employer; or (iii) the date Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination. In the event Executive becomes covered under another employer’s group health plan or otherwise ceases to be eligible for COBRA during the COBRA Premium Period, Executive must immediately notify the Company of such event. Notwithstanding the foregoing, if the Company determines, in its sole discretion, that it cannot pay the COBRA Premiums without a substantial risk of violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company instead shall pay to Executive, on the first day of each calendar month, a fully taxable cash payment equal to the applicable COBRA premiums for that month (including premiums for Executive and Executive’s eligible dependents who have elected and remain enrolled in such COBRA coverage), subject to applicable tax withholdings (such amount, the “Special Cash Payment”), for the remainder of the COBRA Premium Period. Executive may, but is not obligated to, use such Special Cash Payments toward the cost of COBRA premiums.

• Termination for Cause; Resignation Without Good Reason; Death or Disability.

• The Company may terminate Executive’s employment with the Company at any time for Cause. Further, Executive may resign at any time without Good Reason. Executive’s employment with the Company may also be terminated due to Executive’s death or disability.

• If Executive resigns without Good Reason, or the Company terminates Executive’s employment for Cause, or upon Executive’s death or disability, then (i) Executive will no longer vest in the Option and any other stock options held by the Executive, (ii) all payments of compensation by the Company to Executive hereunder will terminate immediately (except as to amounts already earned), and (c) Executive will not be entitled to any severance benefits, including (without limitation) the Severance, COBRA Premiums, Special Cash Payments, unless required by law.

• Termination in Connection with Change in Control. If the Company terminates Executive’s employment no more than three (3) months prior to a Change in Control (as defined herein) or within twelve (12) months after a Change in Control, Executive shall be entitled to receive the following severance benefits:

• The Company shall pay Executive, as severance, twelve (12) months of Executive’s base salary in effect as of the date of Executive’s employment termination, subject to standard payroll deductions and withholdings (the “CIC Severance”). The CIC Severance will be paid in a single lump sum on or about the Company’s first regular payroll date following the 60th day after Executive’s Separation from Service.

• Provided Executive timely elects continued coverage under COBRA, the Company shall pay Executive’s COBRA premiums to continue Executive’s coverage (including coverage for eligible dependents, if applicable) (“CIC COBRA Premiums”) through the period (the “CIC COBRA Premium Period”) starting on Executive’s Separation from Service and ending on the earliest to occur of: (i) twelve (12) months following Executive’s Separation from Service; (ii) the date Executive becomes eligible for group health insurance coverage through a new employer; or (iii) the date Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination. In the event Executive becomes covered under another employer’s group health plan or otherwise ceases to be eligible for COBRA during the CIC COBRA Premium Period, Executive must immediately notify the Company of such event. Notwithstanding the foregoing, if the Company determines, in its sole discretion, that it cannot pay the CIC COBRA Premiums without a substantial risk of violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company instead shall pay to Executive, on the first day of each calendar month, a fully taxable cash payment equal to the applicable COBRA premiums for that month (including premiums for Executive and Executive’s eligible dependents who have elected and remain enrolled in such COBRA coverage), subject to applicable tax withholdings (such amount, the “CIC Special Cash Payment”), for the remainder of the CIC COBRA Premium Period. Executive may, but is not obligated to, use such CIC Special Cash Payments toward the cost of COBRA premiums.

• The Company shall pay Executive, as further severance, a lump sum amount equal to her full bonus target for the calendar year in which the Change in Control occurs (the “CIC Bonus Payment”), to be paid no later than thirty (30) days following Executive’s Separation from Service.

• The Company shall accelerate the vesting of any shares, options, or other equity grants then unvested and outstanding as of the Executive’s Separation from Service, such that Executive will thereafter be 100% vested in any shares, options, or other equity grants awarded by the Company to Executive during Executive’s employment with the Company (the “Vesting Acceleration”).

• Conditions to Receipt of Severance, COBRA Premiums, and Special Cash Payments. The receipt of the Severance, CIC Severance, COBRA Premiums, CIC COBRA Premiums, Special Cash Payments, CIC Special Cash Payments, CIC Bonus Payment, and Vesting Acceleration (collectively, the “Severance Benefits”) will be subject to Executive signing and not revoking a separation agreement and release of claims in a form satisfactory to the Company (the “Separation Agreement”) within a time period specified by the Company, in its sole discretion. No Severance Benefits will be paid or provided until the Separation Agreement becomes effective. Executive shall also resign from all positions and terminate any relationships as an employee, advisor, officer or director with the Company and any of its affiliates, each effective on the date of termination.

• Section 409A. It is intended that all of the severance benefits and other payments payable under this Agreement satisfy, to the greatest extent possible, the exemptions from the application of Code Section 409A provided under Treasury Regulations 1.409A-1(b)(4), 1.409A-1(b)(5) and 1.409A-1(b)(9), and this Agreement will be construed to the greatest extent possible as consistent with those provisions, and to the extent not so exempt, this Agreement (and any definitions hereunder) will be construed in a manner that complies with Section 409A. For purposes of Code Section 409A (including, without limitation, for purposes of Treasury Regulation Section 1.409A-2(b)(2)(iii)), Executive’s right to receive any installment payments under this Agreement (whether severance payments, reimbursements or otherwise) shall be treated as a right to receive a series of separate payments and, accordingly, each installment payment hereunder shall at all times be considered a separate and distinct payment. Notwithstanding any provision to the contrary in this Agreement, if Executive is deemed by the Company at the time of Executive’s Separation from Service to be a “specified employee” for purposes of Code Section 409A(a)(2)(B)(i), and if any of the payments upon Separation from Service set forth herein and/or under any other agreement with the Company are deemed to be “deferred compensation”, then to the extent delayed commencement of any portion of such payments is required in order to avoid a prohibited distribution under Code Section 409A(a)(2)(B)(i) and the related adverse taxation under Section 409A, such payments shall not be provided to Executive prior to the earliest of (i) the expiration of the six-month period measured from the date of Executive’s Separation from Service with the Company, (ii) the date of Executive’s death or (iii) such earlier date as permitted under Section 409A without the imposition of adverse taxation. Upon the first business day following the expiration of such applicable Code Section 409A(a)(2)(B)(i) period, all payments deferred pursuant to this Paragraph shall be paid in a lump sum to Executive, and any remaining payments due shall be paid as otherwise provided herein or in the applicable agreement. No interest shall be due on any amounts so deferred.

• Definitions.

• Cause. For purposes of this Agreement, “Cause” for termination will mean: (a) Executive’s conviction for, or entry of a guilty plea or plea of nolo contendere for, any felony or crime involving dishonesty; (b) Executive’s participation in any fraud against the Company; (c) material breach of Executive’s duties to the Company; (d) persistent unsatisfactory performance of Executive’s job duties after written notice from the Board and a reasonable opportunity to cure (if deemed curable); (e) Executive’s intentional damage to any property of the Company; (f) Executive’s misconduct, or other violation of Company policy that causes harm; (g) Executive’s breach of any written agreement with the Company; and (h) conduct by Executive which in the good faith and reasonable determination of the Board demonstrates gross unfitness to serve, including but not limited to conduct involving moral turpitude, corruption, dishonesty, or other conduct that harms the Company’s reputation or prospects.

• Good Reason. For purposes of this Agreement, Executive shall have “Good Reason” for resignation from employment with the Company if any of the following actions are taken by the Company without Executive’s prior written consent: (a) a material reduction in Executive’s base salary, which the parties agree is a reduction of at least 10% of Executive’s base salary (unless pursuant to a salary reduction program applicable generally to the Company’s similarly situated executive employees); (b) a material reduction in Executive’s duties (including responsibilities and/or authorities), provided, however, that a change in job position shall not be deemed a “material reduction” in and of itself unless Executive’s new duties are materially reduced from the prior duties; or (c) relocation of Executive’s principal place of employment to a place that increases Executive’s one-way commute by more than sixty (60) miles as compared to Executive’s then-current principal place of employment immediately prior to such relocation. In order to resign for Good Reason, Executive must provide written notice to the Board within 30 days after the first occurrence of the event giving rise to Good Reason setting forth the basis for Executive’s resignation, allow the Company at least 30 days from receipt of such written notice to cure such event, and if such event is not reasonably cured within such period, Executive must resign from all positions Executive then holds with the Company not later than 90 days after the expiration of the cure period.

• Change in Control. For purposes of this Agreement, “Change in Control” shall have the meaning set forth in the Lexeo Therapeutics, Inc. 2023 Equity Incentive Plan.

• Proprietary Information Obligations.

• Confidential Information Agreement. As a condition of employment, Executive shall execute and abide by the Company’s standard form of Employee Confidential Information And Inventions Assignment Agreement (the “Confidentiality Agreement”).

• Third-Party Agreements and Information. Executive represents and warrants that Executive’s employment by the Company does not conflict with any prior employment or consulting agreement or other agreement with any third party, and that Executive will perform Executive’s duties to the Company without violating any such agreement. Executive represents and warrants that Executive does not possess confidential information arising out of prior employment, consulting, or other third party relationships, that would be used in connection with Executive’s employment by the Company, except as expressly authorized by that third party. During Executive’s employment by the Company, Executive will use in the performance of Executive’s duties only information which is generally known and used by persons with training and experience comparable to Executive’s own, common knowledge in the industry, otherwise legally in the public domain, or obtained or developed by the Company or by Executive in the course of Executive’s work for the Company. Executive expressly acknowledges that she will not use any confidential or proprietary information of a third-party in connection with the performance of his duties to the Company.

• Outside Activities During Employment.

• Non-Company Business. Except with the prior written consent of the Board, Executive will not during the term of Executive’s employment with the Company undertake or engage in any other employment, occupation or business enterprise, other than ones in which Executive is a passive investor. In any event, Executive may: (i) engage in civic and not- for-profit activities; (ii) engage in activities in connection with personal investments; (iii) serve, following receiving consent from the Board (which shall not unreasonably be withheld), on board of directors positions for up to two (2) organizations, and (iv) serve as an advisor, or as a member of an advisory board, following receiving consent from the Board (which shall not unreasonably be withheld), on up to two (2) organizations; so long as such activities do not materially interfere with the performance of Executive’s duties hereunder.

• No Adverse Interests. Executive agrees not to acquire, assume or participate in, directly or indirectly, any position, investment or interest known to be adverse or antagonistic to the Company, its business or prospects, financial or otherwise. This does not prohibit the Executive from purchasing any publicly listed securities or fundswhich hold publicly listed securities.

• Dispute Resolution. To ensure the timely and economical resolution of disputes that may arise in connection with Executive’s employment with the Company, Executive and the Company agree that any and all disputes, claims, or causes of action arising from or relating to the enforcement, breach, performance, negotiation, execution, or interpretation of this Agreement, the Confidential Information Agreement, or Executive’s employment, or the termination of Executive’s employment, including but not limited to all statutory claims, with the exception of discrimination and harassment claims, will be resolved pursuant to the Federal Arbitration Act, 9 U.S.C. §1-16 (the “FAA”), and to the fullest extent permitted by law, by final, binding and confidential arbitration by a single arbitrator conducted in New York, New York by Judicial Arbitration and Mediation Services Inc. (“JAMS”) under the then applicable JAMS rules appropriate to the relief being sought (the applicable rules are available at the following web addresses: (i) https://www.jamsadr.com/rules-employment-arbitration/ and (ii) https://www.jamsadr.com/rules-comprehensive-arbitration/); provided, however, this arbitration provision not apply to any action or claim that cannot be subject to mandatory arbitration as a matter of law, including, without limitation, claims involving allegations of sexual harassment and discrimination, to the extent such claims are not permitted by applicable law(s) to be submitted to mandatory arbitration and the applicable law(s) are not preempted by the FAA or otherwise invalid (collectively, the “Excluded Claims”). A hard copy of the rules will be provided to Executive upon request. A hard copy of the rules will be provided to Executive upon request. By agreeing to this arbitration procedure, both Executive and the Company waive the right to resolve any such dispute through a trial by jury or judge or administrative proceeding. In addition, all claims, disputes, or causes of action under this section, whether by Executive or the Company, must be brought in an individual capacity, and shall not be brought as a plaintiff (or claimant) or class member in any purported class or representative proceeding, nor joined or consolidated with the claims of any other person or entity. The Arbitrator may not consolidate the claims of more than one person or entity, and may not preside over any form of representative or class proceeding.

To the extent that the preceding sentences regarding class claims or proceedings are found to violate applicable law or are otherwise found unenforceable, any claim(s) alleged or brought on behalf of a class shall proceed in a court of law rather than by arbitration. The Company acknowledges that Executive will have the right to be represented by legal counsel at any arbitration proceeding. Questions of whether a claim is subject to arbitration under this Agreement) shall be decided by a federal court in the State of New York. However, procedural questions which grow out of the dispute and bear on the final disposition are matters for the arbitrator. The arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by law; (b) issue a written arbitration decision, to include the arbitrator’s essential findings and conclusions and a statement of the award; and (c) be authorized to award any or all remedies that Executive or the Company would be entitled to seek in a court of law. Executive and the Company shall equally share all JAMS’ arbitration fees. To the extent JAMS does not collect or Executive otherwise does not pay to JAMS an equal share of all JAMS’ arbitration fees for any reason, and the Company pays JAMS Executive’s share, Executive acknowledges and agrees that the Company shall be entitled to recover from Executive half of the JAMS arbitration fees invoiced to the parties (less any amounts Executive paid to JAMS) in a federal or state court of competent jurisdiction. Except as modified in the Confidential Information Agreement, each party is responsible for its own attorneys’ fees. Nothing in this Agreement is intended to prevent either Executive or the Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Any awards or orders in such arbitrations may be entered and enforced as judgments in the federal and state courts of any competent jurisdiction. To the extent a New York federal court determines that any applicable law prohibits mandatory arbitration of Excluded Claims, if Executive intends to bring multiple claims, including one or more Excluded Claims, the Excluded Claim(s) may be publicly filed with a court, while any other claims will remain subject to mandatory arbitration.

• Section 280G Matters.

• If any payment or benefit Executive will or may receive from the Company or otherwise (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but for this Section, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment provided pursuant to this Agreement (a “Payment”) shall be equal to the Reduced Amount. The “Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax, or (y) the largest portion, up to and including the total, of the Payment, whichever amount (i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state, and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in Executive’s receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction Method”) that results in the greatest economic benefit for Executive. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction Method”).

• Notwithstanding any provision of this Section 12 to the contrary, if the Reduction Method or the Pro Rata Reduction Method would result in any portion of the Payment being subject to taxes pursuant to Section 409A that would not otherwise be subject to taxes pursuant to Section 409A, then the Reduction Method and/or the Pro Rata Reduction Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the greatest economic benefit for Executive as determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without Cause), shall be reduced (or eliminated) before Payments that are not contingent on future events; and (C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A shall be reduced (or eliminated) before Payments that are not deferred compensation within the meaning of Section 409A.

• The Company shall appoint a nationally-recognized accounting, consulting or law firm to make the determinations required by this Section 12. The Company shall bear all expenses with respect to the determinations by such firm required to be made hereunder.

• If Executive receives a Payment for which the Reduced Amount was determined pursuant to clause (x) of and the Internal Revenue Service determines thereafter that some portion of the Payment is subject to the Excise Tax, Executive agrees to promptly return to the Company a sufficient amount of the Payment (after reduction pursuant to clause (x) of Section 12(i)) so that no portion of the remaining Payment is subject to the Excise Tax. For the avoidance of doubt, if the Reduced Amount was determined pursuant to clause (y) of Section 12(i), Executive shall have no obligation to return any portion of the Payment pursuant to the preceding sentence.

• General Provisions.

• Notices. Any notices provided must be in writing and will be deemed effective upon the earlier of personal delivery (including personal delivery by fax) or the next day after sending by overnight carrier, to the Company at its primary office location and to Executive at the address as listed on the Company payroll.

• Severability. Whenever possible, each provision of this Agreement will be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Agreement is held to be invalid, illegal or unenforceable in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality or unenforceability will not affect any other provision or any other jurisdiction, but this Agreement will be reformed, construed and enforced in such jurisdiction to the extent possible in keeping with the intent of the parties.

• Waiver. Any waiver of any breach of any provisions of this Agreement must be in writing to be effective, and it shall not thereby be deemed to have waived any preceding or succeeding breach of the same or any other provision of this Agreement.

• Complete Agreement. This Agreement, together with the Confidentiality Agreement, constitutes the entire agreement between Executive and the Company with regard to this subject matter and is the complete, final, and exclusive embodiment of the Parties’ agreement with regard to this subject matter. This Agreement is entered into without reliance on any promise or representation, written or oral, other than those expressly contained herein, and it supersedes any other such promises, warranties or representations. It is entered into without reliance on any promise or representation other than those expressly contained herein, and it cannot be modified or amended except in a writing signed by a duly authorized officer of the Company.

• Amendments and Waivers. This Agreement cannot be changed, modified or amended, and no provision or requirement hereof may be waived, without the consent in writing of the Executive and the Company. The failure of a party at any time or times to require performance of any provision hereof shall in no manner affect the right of such party at a later time to enforce the same. No waiver by a party of the breach of any term or covenant contained in this Agreement, whether by conduct or otherwise, in any one or more instances, shall be deemed to be, or construed as, a further or continuing waiver of any such breach, or a waiver of the breach of any other term or covenant in this Agreement.

• Counterparts. This Agreement may be executed in separate counterparts, any one of which need not contain signatures of more than one party, but all of which taken together will constitute one and the same Agreement.

• Headings. The headings of the paragraphs hereof are inserted for convenience only and shall not be deemed to constitute a part hereof nor to affect the meaning thereof.

• Successors and Assigns. This Agreement is intended to bind and inure to the benefit of and be enforceable by Executive and the Company, and their respective successors, assigns, heirs, executors and administrators, except that Executive may not assign any of his duties hereunder and he may not assign any of his rights hereunder without the written consent of the Company, which shall not be withheld unreasonably.

• Tax Withholding and Indemnification. All payments and awards contemplated or made pursuant to this Agreement will be subject to withholdings of applicable taxes in compliance with all relevant laws and regulations of all appropriate government authorities. Executive acknowledges and agrees that the Company has neither made any assurances nor any guarantees concerning the tax treatment of any payments or awards contemplated by or made pursuant to this Agreement. Executive has had the opportunity to retain a tax and financial advisor and fully understands the tax and economic consequences of all payments and awards made pursuant to the Agreement.

• Choice of Law. All questions concerning the construction, validity and interpretation of this Agreement will be governed by the laws of the State of New York.

In Witness Whereof, the Parties have executed this Agreement on the day and year written below.

LEXEO THERAPEUTICS, INC.
By:	/s/ R. Nolan Townsend
R. Nolan Townsend
Chief Executive Officer
Date:	4/10/2024
JOSE MANUEL OTERO, PH.D.
/s/ Jose Manuel Otero
Chief Technical Officer
Date:	4/10/2024

CORRECTION TO

EMPLOYMENT AGREEMENT

THIS CORRECTION TO EMPLOYMENT AGREEMENT (this “Correction”) corrects the employment agreement made between Lexeo Therapeutics, Inc. (the “Company”) and Jose Manuel Otero, Ph.D. (the “Executive”) dated April 10, 2024 (the “Employment Agreement”). This Correction is effective as of the effective date of the Employment Agreement (the “Effective Date”). Capitalized terms used herein but not defined shall have the meanings given to such terms in the Employment Agreement.

WHEREAS, the Company and Executive have agreed to amend Section 5.5 of the Employment Agreement in order to correct the termination provisions in connection with change in control.

NOW, THEREFORE, in consideration of the mutual promises and covenants set forth herein, and other good and valuable consideration, receipt of which is hereby acknowledged, the parties to this Correction hereby agree that the Employment Agreement shall be amended as follows:

• Amendment to Section 5.5. As of the Effective Date, the first paragraph of Section 5.5 of the Employment Agreement is hereby amended and restated as follows:

“5.5 Termination in Connection with Change in Control. If the Company terminates

Executive’s employment without Cause, or Executive resigns for Good Reason, no more than three (3) months prior to a Change in Control (as defined herein) or within twelve (12) months after a Change in Control, Executive shall be entitled to receive the following severance benefit (in lieu of, and not in addition to, the benefits described in Section 5.3):”

• Miscellaneous.
• No Other Amendment. Except as modified by this Correction, the Employment Agreement shall remain in full force and effect in all respects without any modification.
• Subsequent Adjustments to Compensation Terms. Any adjustments to Executive’s compensation terms (including but not limited to base salary and bonus) implemented subsequent to the date of the Employment Agreement will be unaffected by the Correction and will remain in effect notwithstanding this Correction.
• At Will. Nothing in this Correction shall modify the at-will nature of the employment relationship.
• Successors and Assigns. The terms and conditions of this Correction shall inure to the benefit of and be binding upon the respective successors and assigns of the parties. Nothing in this Correction, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and assigns any rights, remedies, obligations, or liabilities under or by reason of this Correction, except as expressly provided in this Correction.
• Arbitration: Choice of Laws. This Correction shall be governed in all respects by the dispute resolution provisions of the Employment Agreement (including, without limitation, provisions regarding mandatory arbitration and governing law).
• Titles and Subtitles. The titles and subtitles used in this Correction are used for convenience only and are not to be considered in construing or interpreting this Correction.
• Counterparts. This Correction may be executed in any number of counterparts, each of which shall be enforceable against the parties that execute such counterparts, and all of which together shall constitute one instrument.

IN WITNESS WHEREOF, the parties hereto have executed this Correction as of the date set forth

above.

Lexeo Therapeutics, Inc.:		Executive:
By:
Signature:	/s/ R. Nolan Townsend	Signature:	/s/ Jose Manuel Otero, Ph.D.
Name:	R. Nolan Townsend	Name:	Jose Manuel Otero, Ph.D.
Title:	Chief Executive Officer

EX-10.5

Exhibit 10.5

Lexeo Therapeutics, Inc.

2025 Inducement Equity Incentive Plan

Adopted by the Board of Directors: November 4, 2025

Table of Contents

Page

1. General.	3
2. Shares Subject to the Plan.	3
3. Eligibility and Limitations.	3
4. Options and Stock Appreciation Rights.	4
5. Awards Other Than Options and Stock Appreciation Rights.	6
6. Adjustments upon Changes in Common Stock; Other Corporate Events.	8
7. Administration.	9
8. Tax Withholding	11
9. Miscellaneous.	12
10. Covenants of the Company.	15
11. Additional Rules for Awards Subject to Section 409A.	15
12. Severability.	16
13. Termination of the Plan.	17
14. Definitions.	17

1. General.

(a) Inducement Awards. Each Award under the Plan is intended to qualify as an employment inducement award under the Inducement Listing Rule. All Awards granted under this Plan will be subject to the terms of this Plan.

(b) Plan Purpose. The Company, by means of the Plan, seeks to secure and retain the services of Employees by providing an inducement material to individuals entering into employment with the Company and any Affiliate, including grants to new employees in connection with a merger or acquisition as permitted by Nasdaq Listing Rule 5635(c).

(c) Available Awards. The Plan provides for the grant of the following Awards: (i) Nonstatutory Stock Options; (ii) SARs; (iii) Restricted Stock Awards; (iv) RSU Awards; (v) Performance Awards; and (vi) Other Awards.

(d) Effective Date. The Plan will come into existence on the Effective Date.

2. Shares Subject to the Plan.

(a) Share Reserve. Subject to adjustment in accordance with Section 2(c) and any adjustments as necessary to implement any Capitalization Adjustments, the aggregate number of shares of Common Stock that may be issued pursuant to Awards will not exceed 2,000,000 shares.

(b) [RESERVED]

(c) Share Reserve Operation.

(i) Limit Applies to Common Stock Issued Pursuant to Awards. For clarity, the Share Reserve is a limit on the number of shares of Common Stock that may be issued pursuant to Awards and does not limit the granting of Awards, except that the Company will keep available at all times the number of shares of Common Stock reasonably required to satisfy its obligations to issue shares pursuant to such Awards.

(ii) Actions that Do Not Constitute Issuance of Common Stock and Do Not Reduce Share Reserve. The following actions do not result in an issuance of shares under the Plan and accordingly do not reduce the number of shares subject to the Share Reserve and available for issuance under the Plan: (1) the expiration or termination of any portion of an Award without the shares covered by such portion of the Award having been issued; (2) the settlement of any portion of an Award in cash (i.e., the Participant receives cash rather than Common Stock); (3) the withholding of shares that would otherwise be issued by the Company to satisfy the exercise, strike or purchase price of an Award; or (4) the withholding of shares that would otherwise be issued by the Company to satisfy a tax withholding obligation in connection with an Award.

(iii) Reversion of Previously Issued Shares of Common Stock to Share Reserve. The following shares of Common Stock previously issued pursuant to an Award and accordingly initially deducted from the Share Reserve will be added back to the Share Reserve and again become available for issuance under the Plan: (1) any shares that are forfeited back to or repurchased by the Company because of a failure to meet a contingency or condition required for the vesting of such shares; (2) any shares that are reacquired by the Company to satisfy the exercise, strike or purchase price of an Award; and (3) any shares that are reacquired by the Company to satisfy a tax withholding obligation in connection with an Award.

3. Eligibility and Limitations.

(a) Eligible Award Recipients. Subject to the terms of the Plan, Employees are eligible to receive Awards so long as the following requirements are met:

(i) The Employee was not previously an Employee or Director, or the Employee is to become employed by the Company or any Affiliate following a bona fide period of non-employment (within the meaning of the Inducement Listing Rule); and

(ii) The grant of the Award or Awards is an inducement material to the Employee’s entering into employment with the Company or any Affiliate in accordance with the Inducement Listing Rule.

(b) Specific Award Limitations on Options and SARs. Options and SARs may not be granted to Employees who are providing Continuous Service only to any “parent” of the Company (as such term is defined in Rule 405) unless such Awards comply with the distribution requirements of Section 409A.

4. Options and Stock Appreciation Rights.

Each Option and SAR will have such terms and conditions as determined by the Board. Each Option will be a Nonstatutory Stock Option. Each SAR will be denominated in shares of Common Stock equivalents. The terms and conditions of separate Options and SARs need not be identical; provided, however, that each Option Agreement and SAR Agreement will conform (through incorporation of provisions hereof by reference in the Award Agreement or otherwise) to the substance of each of the following provisions:

(a) Term. No Option or SAR will be exercisable after the expiration of ten years from the date of grant of such Award or such shorter period specified in the Award Agreement.

(b) Exercise or Strike Price. The exercise or strike price of each Option or SAR will not be less than 100% of the Fair Market Value on the date of grant of such Award.

(c) Exercise Procedure and Payment of Exercise Price for Options. In order to exercise an Option, the Participant must provide notice of exercise to the Plan Administrator in accordance with the procedures specified in the Option Agreement or otherwise provided by the Company. The Board has the authority to grant Options that do not permit all of the following methods of payment (or otherwise restrict the ability to use certain methods) and to grant Options that require the consent of the Company to utilize a particular method of payment. The exercise price of an Option may be paid, to the extent permitted by Applicable Law and as determined by the Board, by one or more of the following methods of payment to the extent set forth in the Option Agreement:

(i) by cash or check, bank draft or money order payable to the Company;

(ii) pursuant to a “cashless exercise” program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of the Common Stock subject to the Option, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay the exercise price to the Company from the sales proceeds;

(iii) by delivery to the Company (either by actual delivery or attestation) of shares of Common Stock that are already owned by the Participant free and clear of any liens, claims, encumbrances or security interests, with a Fair Market Value on the date of exercise that does not exceed the exercise price, provided that (1) at the time of exercise the Common Stock is publicly traded, (2) any remaining balance of the exercise price not satisfied by such delivery is paid by the Participant in cash or other permitted form of payment, (3) such delivery would not violate any Applicable Law or agreement restricting the redemption of the Common Stock, (4) any certificated shares are endorsed or accompanied by an executed assignment separate from certificate, and (5) such shares have been held by the Participant for any minimum period necessary to avoid adverse accounting treatment as a result of such delivery;

(iv) by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issuable upon exercise by the largest whole number of shares with a Fair Market Value on the date of exercise that does not exceed the exercise price, provided that (1) such shares used to pay the exercise price will not be exercisable thereafter and (2) any remaining balance of the exercise price not satisfied by such net exercise is paid by the Participant in cash or other permitted form of payment; or

(v) in any other form of consideration that may be acceptable to the Board and permissible under Applicable Law.

(d) Exercise Procedure and Payment of Appreciation Distribution for SARs. In order to exercise any SAR, the Participant must provide notice of exercise to the Plan Administrator in accordance with the SAR Agreement. The appreciation distribution payable to a Participant upon the exercise of a SAR will not be greater than an amount equal to the excess of (i) the aggregate Fair Market Value on the date of exercise of a number of shares of Common Stock equal to the number of Common Stock equivalents that are vested and being exercised under such SAR, over (ii) the strike price of such SAR. Such appreciation distribution may be paid to the Participant in the form of Common Stock or cash (or any combination of Common Stock and cash) or in any other form of payment, as determined by the Board and specified in the SAR Agreement.

(e) Transferability. Options and SARs may not be transferred to third party financial institutions for value. The Board may impose such additional limitations on the transferability of an Option or SAR as it determines. In the absence of any such determination by the Board, the following restrictions on the transferability of Options and SARs will apply, provided that except as explicitly provided herein, neither an Option nor a SAR may be transferred for consideration:

(i) Restrictions on Transfer. An Option or SAR will not be transferable, except by will or by the laws of descent and distribution, and will be exercisable during the lifetime of the Participant only by the Participant; provided, however, that the Board may permit transfer of an Option or SAR in a manner that is not prohibited by applicable tax and securities laws upon the Participant’s request, including to a trust if the Participant is considered to be the sole beneficial owner of such trust (as determined under Section 671 of the Code and applicable state law) while such Option or SAR is held in such trust, provided that the Participant and the trustee enter into a transfer and other agreements required by the Company.

(ii) Domestic Relations Orders. Notwithstanding the foregoing, subject to the execution of transfer documentation in a format acceptable to the Company and subject to the approval of the Board or a duly authorized Officer, an Option or SAR may be transferred pursuant to a domestic relations order.

(f) Vesting. The Board may impose such restrictions on or conditions to the vesting and/or exercisability of an Option or SAR as determined by the Board. Except as otherwise provided in the Award Agreement or other written agreement between a Participant and the Company or an Affiliate, vesting of Options and SARs will cease upon termination of the Participant’s Continuous Service.

(g) Termination of Continuous Service for Cause. Except as explicitly otherwise provided in the Award Agreement or other written agreement between a Participant and the Company or an Affiliate, if a Participant’s Continuous Service is terminated for Cause, the Participant’s Options and SARs will terminate and be forfeited immediately upon such termination of Continuous Service, and the Participant will be prohibited from exercising any portion (including any vested portion) of such Awards on and after the date of such termination of Continuous Service and the Participant will have no further right, title or interest in such forfeited Award, the shares of Common Stock subject to the forfeited Award, or any consideration in respect of the forfeited Award.

(h) Post-Termination Exercise Period Following Termination of Continuous Service for Reasons Other than Cause. Subject to Section 4(i), if a Participant’s Continuous Service terminates for any reason other than for Cause, the Participant may exercise his or her Option or SAR to the extent vested, but only within the following period of time or, if applicable, such other period of time provided in the Award Agreement or other written agreement between a Participant and the Company or an Affiliate; provided, however, that in no event may such Award be exercised after the expiration of its maximum term (as set forth in Section 4(a)):

(i) three months following the date of such termination if such termination is a termination without Cause (other than any termination due to the Participant’s Disability or death);

(ii) 12 months following the date of such termination if such termination is due to the Participant’s Disability;

(iii) 18 months following the date of such termination if such termination is due to the Participant’s death; or

(iv) 18 months following the date of the Participant’s death if such death occurs following the date of such termination but during the period such Award is otherwise exercisable (as provided in (i) or (ii) above).

Following the date of such termination, to the extent the Participant does not exercise such Award within the applicable Post-Termination Exercise Period (or, if earlier, prior to the expiration of the maximum term of such Award), such unexercised portion of the Award will terminate, and the Participant will have no further right, title or interest in the terminated Award, the shares of Common Stock subject to the terminated Award, or any consideration in respect of the terminated Award.

(i) Restrictions on Exercise; Extension of Exercisability. A Participant may not exercise an Option or SAR at any time that the issuance of shares of Common Stock upon such exercise would violate Applicable Law. Except as otherwise provided in the Award Agreement or other written agreement between a Participant and the Company or an Affiliate, if a Participant’s Continuous Service terminates for any reason other than for Cause and, at any time during the last thirty days of the applicable Post-Termination Exercise Period: (i) the exercise of the Participant’s Option or SAR would be prohibited solely because the issuance of shares of Common Stock upon such exercise would violate Applicable Law, or (ii) the immediate sale of any shares of Common Stock issued upon such exercise would violate the Company’s Trading Policy, then the applicable Post-Termination Exercise Period will be extended to the last day of the calendar month that commences following the date the Award would otherwise expire, with an additional extension of the exercise period to the last day of the next calendar month to apply if any of the foregoing restrictions apply at any time during such extended exercise period, generally without limitation as to the maximum permitted number of extensions); provided, however, that in no event may such Award be exercised after the expiration of its maximum term (as set forth in Section 4(a)).

(j) Non-Exempt Employees. No Option or SAR, whether or not vested, granted to an Employee who is a non-exempt employee for purposes of the Fair Labor Standards Act of 1938, as amended, will be first exercisable for any shares of Common Stock until at least six months following the date of grant of such Award. Notwithstanding the foregoing, in accordance with the provisions of the Worker Economic Opportunity Act, any vested portion of such Award may be exercised earlier than six months following the date of grant of such Award in the event of (i) such Participant’s death or Disability, (ii) a Corporate Transaction in which such Award is not assumed, continued or substituted, (iii) a Change in Control, or (iv) such Participant’s retirement (as such term may be defined in the Award Agreement or another applicable agreement or, in the absence of any such definition, in accordance with the Company’s then current employment policies and guidelines). This Section 4(j) is intended to operate so that any income derived by a non-exempt employee in connection with the exercise or vesting of an Option or SAR will be exempt from his or her regular rate of pay.

(k) Whole Shares. Options and SARs may be exercised only with respect to whole shares of Common Stock or their equivalents.

5. Awards Other Than Options and Stock Appreciation Rights.

(a) Restricted Stock Awards and RSU Awards. Each Restricted Stock Award and RSU Award will have such terms and conditions as determined by the Board; provided, however, that each Restricted Stock Award Agreement and RSU Award Agreement will conform (through incorporation of the provisions hereof by reference in the Award Agreement or otherwise) to the substance of each of the following provisions:

(i) Form of Award.

(1) RSAs: To the extent consistent with the Company’s Bylaws, at the Board’s election, shares of Common Stock subject to a Restricted Stock Award may be (i) held in book entry form subject to the Company’s instructions until such shares become vested or any other restrictions lapse, or (ii) evidenced by a certificate, which certificate will be held in such form and manner as determined by the Board. Unless otherwise determined by the Board, a Participant will have voting and other rights as a stockholder of the Company with respect to any shares subject to a Restricted Stock Award.

(2) RSUs: A RSU Award represents a Participant’s right to be issued on a future date the number of shares of Common Stock that is equal to the number of restricted stock units subject to the RSU Award. As a holder of a RSU Award, a Participant is an unsecured creditor of the Company with respect to the Company's unfunded obligation, if any, to issue shares of Common Stock in settlement of such Award and nothing contained in the Plan or any RSU Agreement, and no action taken pursuant to its provisions, will create or be construed to create a trust of any kind or a fiduciary relationship between a Participant and the Company or an Affiliate or any other person. A Participant will not have voting or any other rights as a stockholder of the Company with respect to any RSU Award (unless and until shares are actually issued in settlement of a vested RSU Award).

(ii) Consideration.

(1) RSA: A Restricted Stock Award may be granted in consideration for (A) cash or check, bank draft or money order payable to the Company, or (B) any other form of consideration (including future services) as the Board may determine and permissible under Applicable Law.

(2) RSU: Unless otherwise determined by the Board at the time of grant, a RSU Award will be granted in consideration for the Participant’s services to the Company or an Affiliate, such that the Participant will not be required to make any payment to the Company (other than such services) with respect to the grant or vesting of the RSU Award, or the issuance of any shares of Common Stock pursuant to the RSU Award. If, at the time of grant, the Board determines that any consideration must be paid by the Participant (in a form other than the Participant’s services to the Company or an Affiliate) upon the issuance of any shares of Common Stock in settlement of the RSU Award, such consideration may be paid in any form of consideration as the Board may determine and permissible under Applicable Law.

(iii) Vesting. The Board may impose such restrictions on or conditions to the vesting of a Restricted Stock Award or RSU Award as determined by the Board. Except as otherwise provided in the Award Agreement or other written agreement between a Participant and the Company or an Affiliate, vesting of Restricted Stock Awards and RSU Awards will cease upon termination of the Participant’s Continuous Service.

(iv) Termination of Continuous Service. Except as otherwise provided in the Award Agreement or other written agreement between a Participant and the Company or an Affiliate, if a Participant’s Continuous Service terminates for any reason, (i) the Company may receive through a forfeiture condition or a repurchase right any or all of the shares of Common Stock held by the Participant under his or her Restricted Stock Award that have not vested as of the date of such termination as set forth in the Restricted Stock Award Agreement and (ii) any portion of his or her RSU Award that has not vested will be forfeited upon such termination and the Participant will have no further right, title or interest in the RSU Award, the shares of Common Stock issuable pursuant to the RSU Award, or any consideration in respect of the RSU Award.

(v) Dividends and Dividend Equivalents. Dividends or dividend equivalents may be paid or credited, as applicable, with respect to any shares of Common Stock subject to a Restricted Stock Award or RSU Award, as determined by the Board and specified in the Award Agreement).

(vi) Settlement of RSU Awards. A RSU Award may be settled by the issuance of shares of Common Stock or cash (or any combination thereof) or in any other form of payment, as determined by the Board and specified in the RSU Award Agreement. At the time of grant, the Board may determine to impose such restrictions or conditions that delay such delivery to a date following the vesting of the RSU Award.

(b) Performance Awards. With respect to any Performance Award, the length of any Performance Period, the Performance Goals to be achieved during the Performance Period, the other terms and conditions of such Award, and the measure of whether and to what degree such Performance Goals have been attained will be determined by the Board.

(c) Other Awards. Other forms of Awards valued in whole or in part by reference to, or otherwise based on, Common Stock, including the appreciation in value thereof (e.g., options or stock rights with an exercise price or strike price less than 100% of the Fair Market Value at the time of grant) may be granted either alone or in addition to Awards provided for under Section 4 and the preceding provisions of this Section 5. Subject to the provisions of the Plan, including without limitation the eligibility requirements of Section 3(a), the Board will have sole and complete discretion to determine the Employees to whom and the time or times at which such Other Awards will be granted, the number of shares of Common Stock (or the cash equivalent thereof) to be granted pursuant to such Other Awards and all other terms and conditions of such Other Awards.

6. Adjustments upon Changes in Common Stock; Other Corporate Events.

(a) Capitalization Adjustments. In the event of a Capitalization Adjustment, the Board shall appropriately and proportionately adjust: (i) the class(es) and maximum number of shares of Common Stock subject to the Plan; and (ii) the class(es) and number of securities and exercise price, strike price or purchase price of Common Stock subject to outstanding Awards. The Board shall make such adjustments, and its determination shall be final, binding and conclusive. Notwithstanding the foregoing, no fractional shares or rights for fractional shares of Common Stock shall be created in order to implement any Capitalization Adjustment. The Board shall determine an appropriate equivalent benefit, if any, for any fractional shares or rights to fractional shares that might be created by the adjustments referred to in the preceding provisions of this Section.

(b) Dissolution or Liquidation. Except as otherwise provided in the Award Agreement, in the event of a dissolution or liquidation of the Company, all outstanding Awards (other than Awards consisting of vested and outstanding shares of Common Stock not subject to a forfeiture condition or the Company’s right of repurchase) will terminate immediately prior to the completion of such dissolution or liquidation, and the shares of Common Stock subject to the Company’s repurchase rights or subject to a forfeiture condition may be repurchased or reacquired by the Company notwithstanding the fact that the holder of such Award is providing Continuous Service, provided, however, that the Board may determine to cause some or all Awards to become fully vested, exercisable and/or no longer subject to repurchase or forfeiture (to the extent such Awards have not previously expired or terminated) before the dissolution or liquidation is completed but contingent on its completion.

(c) Corporate Transaction. The following provisions will apply to Awards in the event of a Corporate Transaction unless otherwise provided in the instrument evidencing the Award or any other written agreement between the Company or any Affiliate and the Participant or unless otherwise expressly provided by the Board at the time of grant of an Award.

(i) Awards May Be Assumed. In the event of a Corporate Transaction, any surviving corporation or acquiring corporation (or the surviving or acquiring corporation’s parent company) may assume or continue any or all Awards outstanding under the Plan or may substitute similar awards for Awards outstanding under the Plan (including but not limited to, awards to acquire the same consideration paid to the stockholders of the Company pursuant to the Corporate Transaction), and any reacquisition or repurchase rights held by the Company in respect of Common Stock issued pursuant to Awards may be assigned by the Company to the successor of the Company (or the successor’s parent company, if any), in connection with such Corporate Transaction. A surviving corporation or acquiring corporation (or its parent) may choose to assume or continue only a portion of an Award or substitute a similar award for only a portion of an Award, or may choose to assume or continue the Awards held by some, but not all Participants. The terms of any assumption, continuation or substitution will be set by the Board.

(ii) Awards Held by Current Participants. In the event of a Corporate Transaction in which the surviving corporation or acquiring corporation (or its parent company) does not assume or continue such outstanding Awards or substitute similar awards for such outstanding Awards, then with respect to Awards that have not been assumed, continued or substituted and that are held by Participants whose Continuous Service has not terminated prior to the effective time of the Corporate Transaction (referred to as the “Current Participants”), the vesting of such Awards (and, with respect to Options and Stock Appreciation Rights, the time when such Awards may be exercised) will be accelerated in full to a date prior to the effective time of such Corporate Transaction (contingent upon the effectiveness of the Corporate Transaction) as the Board determines (or, if the Board does not determine such a date, to the date that is five (5) days prior to the effective time of the Corporate Transaction), and such Awards will terminate if not exercised (if applicable) at or prior to the effective time of the Corporate Transaction, and any reacquisition or repurchase rights held by the Company with respect to such Awards will lapse (contingent upon the effectiveness of the Corporate Transaction). With respect to the vesting of Performance Awards that will accelerate upon the occurrence of a Corporate Transaction pursuant to this subsection (ii) and that have multiple vesting levels depending on the level of performance, unless otherwise provided in the Award Agreement or unless otherwise provided by the Board, the vesting of such Performance Awards will accelerate at 100% of the target level upon the occurrence of the Corporate Transaction. With respect to the vesting of Awards that will accelerate upon the occurrence of a Corporate Transaction pursuant to this subsection (ii) and are settled in the form of a cash payment, such cash payment will be made no later than 30 days following the occurrence of the Corporate Transaction.

(iii) Awards Held by Persons other than Current Participants. In the event of a Corporate Transaction in which the surviving corporation or acquiring corporation (or its parent company) does not assume or continue such outstanding Awards or substitute similar awards for such outstanding Awards, then with respect to Awards that have not been assumed, continued or substituted and that are held by persons other than Current Participants, such Awards will terminate if not exercised (if applicable) prior to the occurrence of the Corporate Transaction; provided, however, that any reacquisition or repurchase rights held by the Company with respect to such Awards will not terminate and may continue to be exercised notwithstanding the Corporate Transaction.

(iv) Payment for Awards in Lieu of Exercise. Notwithstanding the foregoing, in the event an Award will terminate if not exercised prior to the effective time of a Corporate Transaction, the Board may provide, in its sole discretion, that the holder of such Award may not exercise such Award but will receive a payment, in such form as may be determined by the Board, equal in value, at the effective time, to the excess, if any, of (1) the value of the property the Participant would have received upon the exercise of the Award (including, at the discretion of the Board, any unvested portion of such Award), over (2) any exercise price payable by such holder in connection with such exercise.

(d) Appointment of Stockholder Representative. As a condition to the receipt of an Award under this Plan, a Participant will be deemed to have agreed that the Award will be subject to the terms of any agreement governing a Corporate Transaction involving the Company, including, without limitation, a provision for the appointment of a stockholder representative that is authorized to act on the Participant’s behalf with respect to any escrow, indemnities and any contingent consideration.

(e) No Restriction on Right to Undertake Transactions. The grant of any Award under the Plan and the issuance of shares pursuant to any Award does not affect or restrict in any way the right or power of the Company or the stockholders of the Company to make or authorize any adjustment, recapitalization, reorganization or other change in the Company’s capital structure or its business, any merger or consolidation of the Company, any issue of stock or of options, rights or options to purchase stock or of bonds, debentures, preferred or prior preference stocks whose rights are superior to or affect the Common Stock or the rights thereof or which are convertible into or exchangeable for Common Stock, or the dissolution or liquidation of the Company, or any sale or transfer of all or any part of its assets or business, or any other corporate act or proceeding, whether of a similar character or otherwise.

7. Administration.

(a) Administration by Board. The Board will administer the Plan unless and until the Board delegates administration of the Plan to a Committee or Committees, as provided in subsection (c) below.

(b) Powers of Board. The Board will have the power, subject to, and within the limitations of, the express provisions of the Plan, including without limitation the eligibility requirements in Section 3(a) and the approval requirements in subsection (e) below:

(i) To determine from time to time (1) which of the persons eligible under the Plan will be granted Awards; (2) when and how each Award will be granted; (3) what type or combination of types of Award will be granted; (4) the provisions of each Award granted (which need not be identical), including the time or times when a person will be permitted to receive an issuance of Common Stock or other payment pursuant to an Award; (5) the number of shares of Common Stock or cash equivalent with respect to which an Award will be granted to each such person; (6) the Fair Market Value applicable to an Award; and (7) the terms of any Performance Award that is not valued in whole or in part by reference to, or otherwise based on, the Common Stock, including the amount of cash payment or other property that may be earned and the timing of payment.

(ii) To construe and interpret the Plan and Awards granted under it, and to establish, amend and revoke rules and regulations for its administration. The Board, in the exercise of this power, may correct any defect, omission or inconsistency in the Plan or in any Award Agreement, in a manner and to the extent it deems necessary or expedient to make the Plan or Award fully effective.

(iii) To settle all controversies regarding the Plan and Awards granted under it.

(iv) To accelerate the time at which an Award may first be exercised or the time during which an Award or any part thereof will vest, notwithstanding the provisions in the Award Agreement stating the time at which it may first be exercised or the time during which it will vest.

(v) To prohibit the exercise of any Option, SAR or other exercisable Award during a period of up to 30 days prior to the consummation of any pending stock dividend, stock split, combination or exchange of shares, merger, consolidation or other distribution (other than normal cash dividends) of Company assets to stockholders, or any other change affecting the shares of Common Stock or the share price of the Common Stock including any Corporate Transaction, for reasons of administrative convenience.

(vi) To suspend or terminate the Plan at any time. Suspension or termination of the Plan will not Materially Impair rights and obligations under any Award granted while the Plan is in effect except with the written consent of the affected Participant.

(vii) To amend the Plan in any respect the Board deems necessary or advisable; provided, however, that stockholder approval will be required for any amendment to the extent required by Applicable Law. Except as provided above, rights under any Award granted before amendment of the Plan will not be Materially Impaired by any amendment of the Plan unless (1) the Company requests the consent of the affected Participant, and (2) such Participant consents in writing.

(viii) To submit any amendment to the Plan for stockholder approval to the extent required by Applicable Law.

(ix) To approve forms of Award Agreements for use under the Plan and to amend the terms of any one or more Awards, including, but not limited to, amendments to provide terms more favorable to the Participant than previously provided in the Award Agreement, subject to any specified limits in the Plan that are not subject to Board discretion; provided however, that, a Participant’s rights under any Award will not be Materially Impaired by any such amendment unless (1) the Company requests the consent of the affected Participant, and (2) such Participant consents in writing.

(x) Generally, to exercise such powers and to perform such acts as the Board deems necessary or expedient to promote the best interests of the Company and that are not in conflict with the provisions of the Plan or Awards.

(xi) To adopt such procedures and sub-plans as are necessary or appropriate to permit and facilitate participation in the Plan by, or take advantage of specific tax treatment for Awards granted to, Employees who are foreign nationals or employed outside the United States (provided that Board approval will not be necessary for immaterial modifications to the Plan or any Award Agreement to ensure or facilitate compliance with the laws of the relevant foreign jurisdiction).

(xii) To effect, at any time and from time to time, subject to the consent of any Participant whose Award is Materially Impaired by such action, (1) the reduction of the exercise price (or strike price) of any outstanding Option or SAR; (2) the cancellation of any outstanding Option or SAR and the grant in substitution therefor of (A) a new Option, SAR, Restricted Stock Award, RSU Award or Other Award, under the Plan or another equity plan of the Company, covering the same or a different number of shares of Common Stock, (B) cash and/or (C) other valuable consideration (as determined by the Board); or (3) any other action that is treated as a repricing under generally accepted accounting principles.

(c) Delegation to Committee.

(i) General. The Board may delegate some or all of the administration of the Plan to a Committee or Committees. If administration of the Plan is delegated to a Committee, the Committee will have, in connection with the administration of the Plan, the powers theretofore possessed by the Board that have been delegated to the Committee, including the power to delegate to another Committee or a subcommittee of the Committee any of the administrative powers the Committee is authorized to exercise (and references in this Plan to the Board will thereafter be to the Committee or subcommittee), subject, however, to the provisions of the Plan and such resolutions, not inconsistent with the provisions of the Plan, as may be adopted from time to time by the Board. Each Committee may retain the authority to concurrently administer the Plan with Committee or subcommittee to which it has delegated its authority hereunder and may, at any time, revest in such Committee some or all of the powers previously delegated. The Board may retain the authority to concurrently administer the Plan with any Committee and may, at any time, revest in the Board some or all of the powers previously delegated.

(ii) Rule 16b-3 Compliance. To the extent an Award is intended to qualify for the exemption from Section 16(b) of the Exchange Act that is available under Rule 16b-3 of the Exchange Act, and subject to the provisions of subsection(e) below, the Award will be granted by the Board or a Committee that consists solely of two or more Non-Employee Directors, as determined under Rule 16b-3(b)(3) of the Exchange Act and thereafter any action establishing or modifying the terms of the Award will be approved by the Board or a Committee meeting such requirements to the extent necessary for such exemption to remain available.

(d) Effect of Board’s Decision. All determinations, interpretations and constructions made by the Board or any Committee in good faith will not be subject to review by any person and will be final, binding and conclusive on all persons.

(e) Approval. Awards granted under the Plan must be approved by a majority of the Company’s “Independent Directors” (as defined under the Nasdaq Listing Rules) or the Compensation Committee.

8. Tax Withholding

(a) Withholding Authorization. As a condition to acceptance of any Award under the Plan, a Participant authorizes withholding from payroll and any other amounts payable to such Participant, and otherwise agree to make adequate provision for (including), any sums required to satisfy any U.S. federal, state, local and/or foreign tax or social insurance contribution withholding obligations of the Company or an Affiliate, if any, which arise in connection with the exercise, vesting or settlement of such Award, as applicable. Accordingly, a Participant may not be able to exercise an Award even though the Award is vested, and the Company shall have no obligation to issue shares of Common Stock subject to an Award, unless and until such obligations are satisfied.

(b) Satisfaction of Withholding Obligation. To the extent permitted by the terms of an Award Agreement, the Company may, in its sole discretion, satisfy any U.S. federal, state, local and/or foreign tax or social insurance withholding obligation relating to an Award by any of the following means or by a combination of such means: (i) causing the Participant to tender a cash payment; (ii) withholding shares of Common Stock from the shares of Common Stock issued or otherwise issuable to the Participant in connection with the Award; (iii) withholding cash from an Award settled in cash; (iv) withholding payment from any amounts otherwise payable to the Participant; (v) by allowing a Participant to effectuate a “cashless exercise” pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board; or (vi) by such other method as may be set forth in the Award Agreement.

(c) No Obligation to Notify or Minimize Taxes; No Liability to Claims. Except as required by Applicable Law the Company has no duty or obligation to any Participant to advise such holder as to the time or manner of exercising such Award. Furthermore, the Company has no duty or obligation to warn or otherwise advise such holder of a pending termination or expiration of an Award or a possible period in which the Award may not be exercised. The Company has no duty or obligation to minimize the tax consequences of an Award to the holder of such Award and will not be liable to any holder of an Award for any adverse tax consequences to such holder in connection with an Award. As a condition to accepting an Award under the Plan, each Participant (i) agrees to not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from such Award or other Company compensation and (ii) acknowledges that such Participant was advised to consult with his or her own personal tax, financial and other legal advisors regarding the tax consequences of the Award and has either done so or knowingly and voluntarily declined to do so. Additionally, each Participant acknowledges any Option or SAR granted under the Plan is exempt from Section 409A only if the exercise or strike price is at least equal to the “fair market value” of the Common Stock on the date of grant as determined by the Internal Revenue Service and there is no other impermissible deferral of compensation associated with the Award. Additionally, as a condition to accepting an Option or SAR granted under the Plan, each Participant agrees not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates in the event that the Internal Revenue Service asserts that such exercise price or strike price is less than the “fair market value” of the Common Stock on the date of grant as subsequently determined by the Internal Revenue Service.

(d) Withholding Indemnification. As a condition to accepting an Award under the Plan, in the event that the amount of the Company’s and/or its Affiliate’s withholding obligation in connection with such Award was greater than the amount actually withheld by the Company and/or its Affiliates, each Participant agrees to indemnify and hold the Company and/or its Affiliates harmless from any failure by the Company and/or its Affiliates to withhold the proper amount.

9. Miscellaneous.

(a) Source of Shares. The stock issuable under the Plan will be shares of authorized but unissued or reacquired Common Stock, including shares repurchased by the Company on the open market or otherwise.

(b) Use of Proceeds from Sales of Common Stock. Proceeds from the sale of shares of Common Stock pursuant to Awards will constitute general funds of the Company.

(c) Corporate Action Constituting Grant of Awards. Corporate action constituting a grant by the Company of an Award to any Participant will be deemed completed as of the date of such corporate action, unless otherwise determined by the Board, regardless of when the instrument, certificate, or letter evidencing the Award is communicated to, or actually received or accepted by, the Participant. In the event that the corporate records (e.g., Board consents, resolutions or minutes) documenting the corporate action approving the grant contain terms (e.g., exercise price, vesting schedule or number of shares) that are inconsistent with those in the Award Agreement or related grant documents as a result of a clerical error in the Award Agreement or related grant documents, the corporate records will control and the Participant will have no legally binding right to the incorrect term in the Award Agreement or related grant documents.

(d) Stockholder Rights. No Participant will be deemed to be the holder of, or to have any of the rights of a holder with respect to, any shares of Common Stock subject to such Award unless and until (i) such Participant has satisfied all requirements for exercise of the Award pursuant to its terms, if applicable, and (ii) the issuance of the Common Stock subject to such Award is reflected in the records of the Company.

(e) No Employment or Other Service Rights. Nothing in the Plan, any Award Agreement or any other instrument executed thereunder or in connection with any Award granted pursuant thereto will confer upon any Participant any right to continue to serve the Company or an Affiliate in the capacity in effect at the time the Award was granted or affect the right of the Company or an Affiliate to terminate at will and without regard to any future vesting opportunity that a Participant may have with respect to any Award (i) the employment of an Employee with or without notice and with or without cause, (ii) the service of a Consultant pursuant to the terms of such Consultant’s agreement with the Company or an Affiliate, or (iii) the service of a Director pursuant to the Bylaws of the Company or an Affiliate, and any applicable provisions of the corporate law of the state or foreign jurisdiction in which the Company or the Affiliate is incorporated, as the case may be. Further, nothing in the Plan, any Award Agreement or any other instrument executed thereunder or in connection with any Award will constitute any promise or commitment by the Company or an Affiliate regarding the fact or nature of future positions, future work assignments, future compensation or any other term or condition of employment or service or confer any right or benefit under the Award or the Plan unless such right or benefit has specifically accrued under the terms of the Award Agreement and/or Plan.

(f) Change in Time Commitment. In the event a Participant’s regular level of time commitment in the performance of his or her services for the Company and any Affiliates is reduced (for example, and without limitation, if the Participant is an Employee of the Company and the Employee has a change in status from a full-time Employee to a part-time Employee or takes an extended leave of absence) after the date of grant of any Award to the Participant, the Board may determine, to the extent permitted by Applicable Law, to (i) make a corresponding reduction in the number of shares or cash amount subject to any portion of such Award that is scheduled to vest or become payable after the date of such change in time commitment, and (ii) in lieu of or in combination with such a reduction, extend the vesting or payment schedule applicable to such Award. In the event of any such reduction, the Participant will have no right with respect to any portion of the Award that is so reduced or extended.

(g) Execution of Additional Documents. As a condition to accepting an Award under the Plan, the Participant agrees to execute any additional documents or instruments necessary or desirable, as determined in the Plan Administrator’s sole discretion, to carry out the purposes or intent of the Award, or facilitate compliance with securities and/or other regulatory requirements, in each case at the Plan Administrator’s request.

(h) Electronic Delivery and Participation. Any reference herein or in an Award Agreement to a “written” agreement or document will include any agreement or document delivered electronically, filed publicly at www.sec.gov (or any successor website thereto) or posted on the Company’s intranet (or other shared electronic medium controlled by the Company to which the Participant has access). By accepting any Award the Participant consents to receive documents by electronic delivery and to participate in the Plan through any on-line electronic system established and maintained by the Plan Administrator or another third party selected by the Plan Administrator. The form of delivery of any Common Stock (e.g., a stock certificate or electronic entry evidencing such shares) shall be determined by the Company.

(i) Clawback/Recovery. All Awards granted under the Plan will be subject to recoupment in accordance with any clawback policy that the Company is required to adopt pursuant to the listing standards of any national securities exchange or association on which the Company’s securities are listed or as is otherwise required by the Dodd-Frank Wall Street Reform and Consumer Protection Act or other Applicable Law and any clawback policy that the Company otherwise adopts, to the extent applicable and permissible under Applicable Law. In addition, the Board may impose such other clawback, recovery or recoupment provisions in an Award Agreement as the Board determines necessary or appropriate, including but not limited to a reacquisition right in respect of previously acquired shares of Common Stock or other cash or property upon the occurrence of Cause. No recovery of compensation under such a clawback policy will be an event giving rise to a Participant’s right to voluntary terminate employment upon a “resignation for good reason,” or for a “constructive termination” or any similar term under any plan of or agreement with the Company.

(j) Securities Law Compliance. A Participant will not be issued any shares in respect of an Award unless either (i) the shares are registered under the Securities Act; or (ii) the Company has determined that such issuance would be exempt from the registration requirements of the Securities Act. Each Award also must comply with other Applicable Law governing the Award, and a Participant will not receive such shares if the Company determines that such receipt would not be in material compliance with Applicable Law.

(k) Transfer or Assignment of Awards; Issued Shares. Except as expressly provided in the Plan or the form of Award Agreement, Awards granted under the Plan may not be transferred or assigned by the Participant. After the vested shares subject to an Award have been issued, or in the case of Restricted Stock and similar awards, after the issued shares have vested, the holder of such shares is free to assign, hypothecate, donate, encumber or otherwise dispose of any interest in such shares provided that any such actions are in compliance with the provisions herein, the terms of the Trading Policy and Applicable Law.

(l) Effect on Other Employee Benefit Plans. The value of any Award granted under the Plan, as determined upon grant, vesting or settlement, shall not be included as compensation, earnings, salaries, or other similar terms used when calculating any Participant’s benefits under any employee benefit plan sponsored by the Company or any Affiliate, except as such plan otherwise expressly provides. The Company expressly reserves its rights to amend, modify, or terminate any of the Company's or any Affiliate's employee benefit plans.

(m) Deferrals. To the extent permitted by Applicable Law, the Board, in its sole discretion, may determine that the delivery of Common Stock or the payment of cash, upon the exercise, vesting or settlement of all or a portion of any Award may be deferred and may also establish programs and procedures for deferral elections to be made by Participants. Deferrals by Participants will be made in accordance with the requirements of Section 409A.

(n) Section 409A. Unless otherwise expressly provided for in an Award Agreement, the Plan and Award Agreements will be interpreted to the greatest extent possible in a manner that makes the Plan and the Awards granted hereunder exempt from Section 409A, and, to the extent not so exempt, in compliance with the requirements of Section 409A. If the Board determines that any Award granted hereunder is not exempt from and is therefore subject to Section 409A, the Award Agreement evidencing such Award will incorporate the terms and conditions necessary to avoid the consequences specified in Section 409A(a)(1) of the Code, and to the extent an Award Agreement is silent on terms necessary for compliance, such terms are hereby incorporated by reference into the Award Agreement. Notwithstanding anything to the contrary in this Plan (and unless the Award Agreement specifically provides otherwise), if the shares of Common Stock are publicly traded, and if a Participant holding an Award that constitutes “deferred compensation” under Section 409A is a “specified employee” for purposes of Section 409A, no distribution or payment of any amount that is due because of a “separation from service” (as defined in Section 409A without regard to alternative definitions thereunder) will be issued or paid before the date that is six months and one day following the date of such Participant’s “separation from service” or, if earlier, the date of the Participant’s death, unless such distribution or payment can be made in a manner that complies with Section 409A, and any amounts so deferred will be paid in a lump sum on the day after such six month period elapses, with the balance paid thereafter on the original schedule.

(o) Choice of Law. This Plan and any controversy arising out of or relating to this Plan shall be governed by, and construed in accordance with, the internal laws of the State of Delaware, without regard to conflict of law principles that would result in any application of any law other than the law of the State of Delaware.

10. Covenants of the Company.

(a) Compliance with Law. The Company will seek to obtain from each regulatory commission or agency, as may be deemed to be necessary, having jurisdiction over the Plan such authority as may be required to grant Awards and to issue and sell shares of Common Stock upon exercise or vesting of the Awards; provided, however, that this undertaking will not require the Company to register under the Securities Act the Plan, any Award or any Common Stock issued or issuable pursuant to any such Award. If, after reasonable efforts and at a reasonable cost, the Company is unable to obtain from any such regulatory commission or agency the authority that counsel for the Company deems necessary or advisable for the lawful issuance and sale of Common Stock under the Plan, the Company will be relieved from any liability for failure to issue and sell Common Stock upon exercise or vesting of such Awards unless and until such authority is obtained. A Participant is not eligible for the grant of an Award or the subsequent issuance of Common Stock pursuant to the Award if such grant or issuance would be in violation of any Applicable Law.

11. Additional Rules for Awards Subject to Section 409A.

(a) Application. Unless the provisions of this Section of the Plan are expressly superseded by the provisions in the form of Award Agreement, the provisions of this Section shall apply and shall supersede anything to the contrary set forth in the Award Agreement for a Non-Exempt Award.

(b) Non-Exempt Awards Subject to Non-Exempt Severance Arrangements. To the extent a Non-Exempt Award is subject to Section 409A due to application of a Non-Exempt Severance Arrangement, the following provisions of this subsection (b) apply.

(i) If the Non-Exempt Award vests in the ordinary course during the Participant’s Continuous Service in accordance with the vesting schedule set forth in the Award Agreement, and does not accelerate vesting under the terms of a Non-Exempt Severance Arrangement, in no event will the shares be issued in respect of such Non-Exempt Award any later than the later of: (i) December 31st of the calendar year that includes the applicable vesting date, or (ii) the 60th day that follows the applicable vesting date.

(ii) If vesting of the Non-Exempt Award accelerates under the terms of a Non-Exempt Severance Arrangement in connection with the Participant’s Separation from Service, and such vesting acceleration provisions were in effect as of the date of grant of the Non-Exempt Award and, therefore, are part of the terms of such Non-Exempt Award as of the date of grant, then the shares will be earlier issued in settlement of such Non-Exempt Award upon the Participant’s Separation from Service in accordance with the terms of the Non-Exempt Severance Arrangement, but in no event later than the 60th day that follows the date of the Participant’s Separation from Service. However, if at the time the shares would otherwise be issued the Participant is subject to the distribution limitations contained in Section 409A applicable to “specified employees,” as defined in Section 409A(a)(2)(B)(i) of the Code, such shares shall not be issued before the date that is six months following the date of such Participant’s Separation from Service, or, if earlier, the date of the Participant’s death that occurs within such six month period.

(iii) If vesting of a Non-Exempt Award accelerates under the terms of a Non-Exempt Severance Arrangement in connection with a Participant’s Separation from Service, and such vesting acceleration provisions were not in effect as of the date of grant of the Non-Exempt Award and, therefore, are not a part of the terms of such Non-Exempt Award on the date of grant, then such acceleration of vesting of the Non-Exempt Award shall not accelerate the issuance date of the shares, but the shares shall instead be issued on the same schedule as set forth in the Grant Notice as if they had vested in the ordinary course during the Participant’s Continuous Service, notwithstanding the vesting acceleration of the Non-Exempt Award. Such issuance schedule is intended to satisfy the requirements of payment on a specified date or pursuant to a fixed schedule, as provided under Treasury Regulations Section 1.409A-3(a)(4).

(c) Treatment of Non-Exempt Awards Upon a Corporate Transaction for Employees. The provisions of this subsection (c) shall apply and shall supersede anything to the contrary set forth in the Plan with respect to the permitted treatment of any Non-Exempt Award in connection with a Corporate Transaction if the Participant was an Employee upon the applicable date of grant of the Non-Exempt Award.

(i) Vested Non-Exempt Awards. The following provisions shall apply to any Vested Non-Exempt Award in connection with a Corporate Transaction:

(1) If the Corporate Transaction is also a Section 409A Change in Control then the Acquiring Entity may not assume, continue or substitute the Vested Non-Exempt Award. Upon the Section 409A Change in Control the settlement of the Vested Non-Exempt Award will automatically be accelerated and the shares will be immediately issued in respect of the Vested Non-Exempt Award. Alternatively, the Company may instead provide that the Participant will receive a cash settlement equal to the Fair Market Value of the shares that would otherwise be issued to the Participant upon the Section 409A Change in Control.

(2) If the Corporate Transaction is not also a Section 409A Change in Control, then the Acquiring Entity must either assume, continue or substitute each Vested Non-Exempt Award. The shares to be issued in respect of the Vested Non-Exempt Award shall be issued to the Participant by the Acquiring Entity on the same schedule that the shares would have been issued to the Participant if the Corporate Transaction had not occurred. In the Acquiring Entity’s discretion, in lieu of an issuance of shares, the Acquiring Entity may instead substitute a cash payment on each applicable issuance date, equal to the Fair Market Value of the shares that would otherwise be issued to the Participant on such issuance dates, with the determination of the Fair Market Value of the shares made on the date of the Corporate Transaction.

(ii) Unvested Non-Exempt Awards. The following provisions shall apply to any Unvested Non-Exempt Award unless otherwise determined by the Board pursuant to subsection (e) of this Section.

(1) In the event of a Corporate Transaction, the Acquiring Entity shall assume, continue or substitute any Unvested Non-Exempt Award. Unless otherwise determined by the Board, any Unvested Non-Exempt Award will remain subject to the same vesting and forfeiture restrictions that were applicable to the Award prior to the Corporate Transaction. The shares to be issued in respect of any Unvested Non-Exempt Award shall be issued to the Participant by the Acquiring Entity on the same schedule that the shares would have been issued to the Participant if the Corporate Transaction had not occurred. In the Acquiring Entity’s discretion, in lieu of an issuance of shares, the Acquiring Entity may instead substitute a cash payment on each applicable issuance date, equal to the Fair Market Value of the shares that would otherwise be issued to the Participant on such issuance dates, with the determination of Fair Market Value of the shares made on the date of the Corporate Transaction.

(2) If the Acquiring Entity will not assume, substitute or continue any Unvested Non-Exempt Award in connection with a Corporate Transaction, then such Award shall automatically terminate and be forfeited upon the Corporate Transaction with no consideration payable to any Participant in respect of such forfeited Unvested Non-Exempt Award. Notwithstanding the foregoing, to the extent permitted and in compliance with the requirements of Section 409A, the Board may in its discretion determine to elect to accelerate the vesting and settlement of the Unvested Non-Exempt Award upon the Corporate Transaction, or instead substitute a cash payment equal to the Fair Market Value of such shares that would otherwise be issued to the Participant, as further provided in subsection (e)(ii) below. In the absence of such discretionary election by the Board, any Unvested Non-Exempt Award shall be forfeited without payment of any consideration to the affected Participants if the Acquiring Entity will not assume, substitute or continue the Unvested Non-Exempt Awards in connection with the Corporate Transaction.

(3) The foregoing treatment shall apply with respect to all Unvested Non-Exempt Awards upon any Corporate Transaction, and regardless of whether or not such Corporate Transaction is also a Section 409A Change in Control.

12. Severability.

If all or any part of the Plan or any Award Agreement is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity shall not invalidate any portion of the Plan or such Award Agreement not declared to be unlawful or invalid. Any Section of the Plan or any Award Agreement (or part of such a Section) so declared to be unlawful or invalid shall, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid.

13. Termination of the Plan.

The Board may suspend or terminate the Plan at any time. No Awards may be granted under the Plan while the Plan is suspended or after it is terminated.

14. Definitions.

As used in the Plan, the following definitions apply to the capitalized terms indicated below:

(a) “Acquiring Entity” means the surviving or acquiring corporation (or its parent company) in connection with a Corporate Transaction.

(b) “Affiliate” means, at the time of determination, any “parent” or “subsidiary” of the Company as such terms are defined in Rule 405 promulgated under the Securities Act. The Board may determine the time or times at which “parent” or “subsidiary” status is determined within the foregoing definition.

(c) “Applicable Law” means shall mean any applicable securities, federal, state, foreign, material local or municipal or other law, statute, constitution, principle of common law, resolution, ordinance, code, edict, decree, rule, listing rule, regulation, judicial decision, ruling or requirement issued, enacted, adopted, promulgated, implemented or otherwise put into effect by or under the authority of any Governmental Body (including under the authority of any applicable self-regulating organization such as the Nasdaq Stock Market, New York Stock Exchange, or the Financial Industry Regulatory Authority).

(d) “Award” means any right to receive Common Stock, cash or other property granted under the Plan (including a Nonstatutory Stock Option, a Restricted Stock Award, a RSU Award, a SAR, a Performance Award or any Other Award).

(e) “Award Agreement” means a written agreement between the Company and a Participant evidencing the terms and conditions of an Award. The Award Agreement generally consists of the Grant Notice and the agreement containing the written summary of the general terms and conditions applicable to the Award and which is provided to a Participant along with the Grant Notice.

(f) “Board” means the Board of Directors of the Company (or its designee). Any decision or determination made by the Board shall be a decision or determination that is made in the sole discretion of the Board (or its designee), and such decision or determination shall be final and binding on all Participants.

(g) “Capitalization Adjustment” means any change that is made in, or other events that occur with respect to, the Common Stock subject to the Plan or subject to any Award after the Effective Date without the receipt of consideration by the Company through merger, consolidation, reorganization, recapitalization, reincorporation, stock dividend, dividend in property other than cash, large nonrecurring cash dividend, stock split, reverse stock split, liquidating dividend, combination of shares, exchange of shares, change in corporate structure or any similar equity restructuring transaction, as that term is used in Statement of Financial Accounting Standards Board Accounting Standards Codification Topic 718 (or any successor thereto). Notwithstanding the foregoing, the conversion of any convertible securities of the Company will not be treated as a Capitalization Adjustment.

(h) “Cause” has the meaning ascribed to such term in any written agreement between the Participant and the Company defining such term and, in the absence of such agreement, such term means, with respect to a Participant, the occurrence of any of the following events: (i) such Participant’s attempted commission of, or participation in, a fraud or act of dishonesty against the Company; (ii) such Participant’s intentional, material violation of any contract or agreement between the Participant and the Company or of any statutory duty owed to the Company; (iii) such Participant’s unauthorized use or disclosure of the Company’s confidential information or trade secrets; or (iv) such Participant’s gross or willful misconduct. The determination that a termination of the Participant’s Continuous Service is either for Cause or without Cause will be made by the Board with respect to Participants who are executive officers of the Company and by the Company’s Chief Executive Officer with respect to Participants who are not executive officers of the Company. Any determination by the Company that the Continuous Service of a Participant was terminated with or without Cause for the purposes of outstanding Awards held by such Participant will have no effect upon any determination of the rights or obligations of the Company or such Participant for any other purpose.

(i) “Change in Control” or “Change of Control” means the occurrence, in a single transaction or in a series of related transactions, of any one or more of the following events; provided, however, to the extent necessary to avoid adverse personal income tax consequences to the Participant in connection with an Award, also constitutes a Section 409A Change in Control:

(i) any Exchange Act Person becomes the Owner, directly or indirectly, of securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities other than by virtue of a merger, consolidation or similar transaction. Notwithstanding the foregoing, a Change in Control shall not be deemed to occur (A) on account of the acquisition of securities of the Company directly from the Company, (B) on account of the acquisition of securities of the Company by an investor, any affiliate thereof or any other Exchange Act Person that acquires the Company’s securities in a transaction or series of related transactions the primary purpose of which is to obtain financing for the Company through the issuance of equity securities, or (C) solely because the level of Ownership held by any Exchange Act Person (the “Subject Person”) exceeds the designated percentage threshold of the outstanding voting securities as a result of a repurchase or other acquisition of voting securities by the Company reducing the number of shares outstanding, provided that if a Change in Control would occur (but for the operation of this sentence) as a result of the acquisition of voting securities by the Company, and after such share acquisition, the Subject Person becomes the Owner of any additional voting securities that, assuming the repurchase or other acquisition had not occurred, increases the percentage of the then outstanding voting securities Owned by the Subject Person over the designated percentage threshold, then a Change in Control shall be deemed to occur;

(ii) there is consummated a merger, consolidation or similar transaction involving (directly or indirectly) the Company and, immediately after the consummation of such merger, consolidation or similar transaction, the stockholders of the Company immediately prior thereto do not Own, directly or indirectly, either (A) outstanding voting securities representing more than 50% of the combined outstanding voting power of the surviving Entity in such merger, consolidation or similar transaction or (B) more than 50% of the combined outstanding voting power of the parent of the surviving Entity in such merger, consolidation or similar transaction, in each case in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such transaction;

(iii) there is consummated a sale, lease, exclusive license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries, other than a sale, lease, license or other disposition of all or substantially all of the consolidated assets of the Company and its Subsidiaries to an Entity, more than 50% of the combined voting power of the voting securities of which are Owned by stockholders of the Company in substantially the same proportions as their Ownership of the outstanding voting securities of the Company immediately prior to such sale, lease, license or other disposition; or

(iv) individuals who, on the date the Plan is adopted by the Board, are members of the Board (the “Incumbent Board”) cease for any reason to constitute at least a majority of the members of the Board; provided, however, that if the appointment or election (or nomination for election) of any new Board member was approved or recommended by a majority vote of the members of the Incumbent Board then still in office, such new member shall, for purposes of this Plan, be considered as a member of the Incumbent Board.

Notwithstanding the foregoing or any other provision of this Plan, (A) the term Change in Control shall not include a sale of assets, merger or other transaction effected exclusively for the purpose of changing the domicile of the Company, and (B) the definition of Change in Control (or any analogous term) in an individual written agreement between the Company or any Affiliate and the Participant shall supersede the foregoing definition with respect to Awards subject to such agreement; provided, however, that if no definition of Change in Control or any analogous term is set forth in such an individual written agreement, the foregoing definition shall apply.

(j) “Code” means the Internal Revenue Code of 1986, as amended, including any applicable regulations and guidance thereunder.

(k) “Committee” means the Compensation Committee and any other committee of Directors to whom authority has been delegated by the Board or Compensation Committee in accordance with the Plan.

(l) “Common Stock” means the common stock of the Company.

(m) “Company” means Lexeo Therapeutics, Inc., a Delaware corporation.

(n) “Compensation Committee” means the Compensation Committee of the Board.

(o) “Consultant” means any person, including an advisor, who is (i) engaged by the Company or an Affiliate to render consulting or advisory services and is compensated for such services, or (ii) serving as a member of the board of directors of an Affiliate and is compensated for such services. However, service solely as a Director, or payment of a fee for such service, will not cause a Director to be considered a “Consultant” for purposes of the Plan. Notwithstanding the foregoing, a person is treated as a Consultant under this Plan only if a Form S-8 Registration Statement under the Securities Act is available to register either the offer or the sale of the Company’s securities to such person.

(p) “Continuous Service” means that the Participant’s service with the Company or an Affiliate, whether as an Employee, Director or Consultant, is not interrupted or terminated. A change in the capacity in which the Participant renders service to the Company or an Affiliate as an Employee, Director or Consultant or a change in the Entity for which the Participant renders such service, provided that there is no interruption or termination of the Participant’s service with the Company or an Affiliate, will not terminate a Participant’s Continuous Service; provided, however, that if the Entity for which a Participant is rendering services ceases to qualify as an Affiliate, as determined by the Board, such Participant’s Continuous Service will be considered to have terminated on the date such Entity ceases to qualify as an Affiliate. For example, a change in status from an Employee of the Company to a Consultant of an Affiliate or to a Director will not constitute an interruption of Continuous Service. To the extent permitted by law, the Board or the chief executive officer of the Company, in that party’s sole discretion, may determine whether Continuous Service will be considered interrupted in the case of (i) any leave of absence approved by the Board or chief executive officer, including sick leave, military leave or any other personal leave, or (ii) transfers between the Company, an Affiliate, or their successors. Notwithstanding the foregoing, a leave of absence will be treated as Continuous Service for purposes of vesting in an Award only to such extent as may be provided in the Company’s leave of absence policy, in the written terms of any leave of absence agreement or policy applicable to the Participant, or as otherwise required by law. In addition, to the extent required for exemption from or compliance with Section 409A, the determination of whether there has been a termination of Continuous Service will be made, and such term will be construed, in a manner that is consistent with the definition of “separation from service” as defined under Treasury Regulation Section 1.409A-1(h) (without regard to any alternative definition thereunder).

(q) “Corporate Transaction” means the consummation, in a single transaction or in a series of related transactions, of any one or more of the following events:

(i) a sale or other disposition of all or substantially all, as determined by the Board, of the consolidated assets of the Company and its Subsidiaries;

(ii) a sale or other disposition of at least 50% of the outstanding securities of the Company;

(iii) a merger, consolidation or similar transaction following which the Company is not the surviving corporation; or

(iv) a merger, consolidation or similar transaction following which the Company is the surviving corporation but the shares of Common Stock outstanding immediately preceding the merger, consolidation or similar transaction are converted or exchanged by virtue of the merger, consolidation or similar transaction into other property, whether in the form of securities, cash or otherwise.

(r) “Director” means a member of the Board.

(s) “determine” or “determined” means as determined by the Board or the Committee (or its designee) in its sole discretion.

(t) “Disability” means, with respect to a Participant, such Participant is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months, as provided in Section 22(e)(3) of the Code, and will be determined by the Board on the basis of such medical evidence as the Board deems warranted under the circumstances.

(u) “Effective Date” means the date the Plan is first approved by the Board.

(v) “Employee” means any person employed by the Company or an Affiliate. However, service solely as a Director, or payment of a fee for such services, will not cause a Director to be considered an “Employee” for purposes of the Plan. For the avoidance of doubt, a person who already is serving as a Director prior to becoming an Employee will not be eligible to be granted an Award under the Plan unless permitted under the Inducement Listing Rule. The Company shall determine in good faith and in the exercise of its discretion whether an individual has become or has ceased to be an Employee and the effective date of such individual’s employment or termination of employment, as the case may be. For purposes of an individual’s rights, if any, under the Plan as of the time of the Company’s determination, all such determinations by the Company shall be final, binding and conclusive, notwithstanding that the Company or any court of law or Governmental Body subsequently makes a contrary determination.

(w) “Employer” means the Company or the Affiliate of the Company that employs the Participant.

(x) “Entity” means a corporation, partnership, limited liability company or other entity.

(y) “Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder.

(z) “Exchange Act Person” means any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act), except that “Exchange Act Person” will not include (i) the Company or any Subsidiary of the Company, (ii) any employee benefit plan of the Company or any Subsidiary of the Company or any trustee or other fiduciary holding securities under an employee benefit plan of the Company or any Subsidiary of the Company, (iii) an underwriter temporarily holding securities pursuant to a registered public offering of such securities, (iv) an Entity Owned, directly or indirectly, by the stockholders of the Company in substantially the same proportions as their Ownership of stock of the Company; or (v) any natural person, Entity or “group” (within the meaning of Section 13(d) or 14(d) of the Exchange Act) that, as of the Effective Date, is the Owner, directly or indirectly, of securities of the Company representing more than 50% of the combined voting power of the Company’s then outstanding securities.

(aa) “Fair Market Value” means, as of any date, unless otherwise determined by the Board, the value of the Common Stock (as determined on a per share or aggregate basis, as applicable) determined as follows:

(i) If the Common Stock is listed on any established stock exchange or traded on any established market, the Fair Market Value will be the closing sales price for such stock as quoted on such exchange or market (or the exchange or market with the greatest volume of trading in the Common Stock) on the date of determination, as reported in a source the Board deems reliable.

(ii) If there is no closing sales price for the Common Stock on the date of determination, then the Fair Market Value will be the closing selling price on the last preceding date for which such quotation exists.

(iii) In the absence of such markets for the Common Stock, or if otherwise determined by the Board, the Fair Market Value will be determined by the Board in good faith and in a manner that complies with Sections 409A and 422 of the Code.

(bb) “Governmental Body” means any: (a) nation, state, commonwealth, province, territory, county, municipality, district or other jurisdiction of any nature; (b) federal, state, local, municipal, foreign or other government; (c) governmental or regulatory body, or quasi-governmental body of any nature (including any governmental division, department, administrative agency or bureau, commission, authority, instrumentality, official, ministry, fund, foundation, center, organization, unit, body or Entity and any court or other tribunal, and for the avoidance of doubt, any Tax authority) or other body exercising similar powers or authority; or (d) self-regulatory organization (including the Nasdaq Stock Market, New York Stock Exchange, and the Financial Industry Regulatory Authority).

(cc) “Grant Notice” means the notice provided to a Participant that he or she has been granted an Award under the Plan and which includes the name of the Participant, the type of Award, the date of grant of the Award, number of shares of Common Stock subject to the Award or potential cash payment right, (if any), the vesting schedule for the Award (if any) and other key terms applicable to the Award.

(dd) “Incentive Stock Option” means an option that is intended to be, and qualifies as, an “incentive stock option” within the meaning of Section 422 of the Code.

(ee) “Inducement Listing Rule” means Nasdaq Listing Rule 5635(c)(4) and the official regulations and other official interpretive material and guidance issued under such rule.

(ff) “Materially Impair” means any amendment to the terms of the Award that materially adversely affects the Participant’s rights under the Award. A Participant's rights under an Award will not be deemed to have been Materially Impaired by any such amendment if the Board, in its sole discretion, determines that the amendment, taken as a whole, does not materially impair the Participant's rights. For example, the following types of amendments to the terms of an Award do not Materially Impair the Participant’s rights under the Award: (i) imposition of reasonable restrictions on the minimum number of shares subject to an Option that may be exercised; (ii) to clarify the manner of exemption from, or to bring the Award into compliance with or qualify it for an exemption from, Section 409A; or (iii) to comply with other Applicable Laws.

(gg) “Non-Employee Director” means a Director who either (i) is not a current employee or officer of the Company or an Affiliate, does not receive compensation, either directly or indirectly, from the Company or an Affiliate for services rendered as a consultant or in any capacity other than as a Director (except for an amount as to which disclosure would not be required under Item 404(a) of Regulation S-K promulgated pursuant to the Securities Act (“Regulation S-K”)), does not possess an interest in any other transaction for which disclosure would be required under Item 404(a) of Regulation S-K, and is not engaged in a business relationship for which disclosure would be required pursuant to Item 404(b) of Regulation S-K; or (ii) is otherwise considered a “non-employee director” for purposes of Rule 16b-3.

(hh) “Non-Exempt Award” means any Award that is subject to, and not exempt from, Section 409A, including as the result of (i) a deferral of the issuance of the shares subject to the Award which is elected by the Participant or imposed by the Company, (ii) the terms of any Non-Exempt Severance Agreement.

(ii) “Non-Exempt Severance Arrangement” means a severance arrangement or other agreement between the Participant and the Company that provides for acceleration of vesting of an Award and issuance of the shares in respect of such Award upon the Participant’s termination of employment or separation from service (as such term is defined in Section 409A(a)(2)(A)(i) of the Code (and without regard to any alternative definition thereunder) (“Separation from Service”) and such severance benefit does not satisfy the requirements for an exemption from application of Section 409A provided under Treasury Regulations Section 1.409A-1(b)(4), 1.409A-1(b)(9) or otherwise.

(jj) “Nonstatutory Stock Option” means any option granted pursuant to Section 4 of the Plan that does not qualify as an Incentive Stock Option.

(kk) “Officer” means a person who is an officer of the Company within the meaning of Section 16 of the Exchange Act.

(ll) “Option” means a Nonstatutory Stock Option to purchase shares of Common Stock granted pursuant to the Plan.

(mm) “Option Agreement” means a written agreement between the Company and the Optionholder evidencing the terms and conditions of the Option grant. The Option Agreement includes the Grant Notice for the Option and the agreement containing the written summary of the general terms and conditions applicable to the Option and which is provided to a Participant along with the Grant Notice. Each Option Agreement will be subject to the terms and conditions of the Plan.

(nn) “Optionholder” means a person to whom an Option is granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Option.

(oo) “Other Award” means an award based in whole or in part by reference to the Common Stock which is granted pursuant to the terms and conditions of Section 5(c).

(pp) “Other Award Agreement” means a written agreement between the Company and a holder of an Other Award evidencing the terms and conditions of an Other Award grant. Each Other Award Agreement will be subject to the terms and conditions of the Plan.

(qq) “Own,” “Owned,” “Owner,” “Ownership” means that a person or Entity will be deemed to “Own,” to have “Owned,” to be the “Owner” of, or to have acquired “Ownership” of securities if such person or Entity, directly or indirectly, through any contract, arrangement, understanding, relationship or otherwise, has or shares voting power, which includes the power to vote or to direct the voting, with respect to such securities.

(rr) “Participant” means an Employee to whom an Award is granted pursuant to the Plan or, if applicable, such other person who holds an outstanding Award.

(ss) “Performance Award” means an Award that may vest or may be exercised or a cash award that may vest or become earned and paid contingent upon the attainment during a Performance Period of certain Performance Goals and which is granted under the terms and conditions of Section 5(b) pursuant to such terms as are approved by the Board. In addition, to the extent permitted by Applicable Law and set forth in the applicable Award Agreement, the Board may determine that cash or other property may be used in payment of Performance Awards. Performance Awards that are settled in cash or other property are not required to be valued in whole or in part by reference to, or otherwise based on, the Common Stock.

(tt) “Performance Criteria” means the one or more criteria that the Board will select for purposes of establishing the Performance Goals for a Performance Period. The Performance Criteria that will be used to establish such Performance Goals may be based on any measure of performance selected by the Board.

(uu) “Performance Goals” means, for a Performance Period, the one or more goals established by the Board for the Performance Period based upon the Performance Criteria. Performance Goals may be based on a Company-wide basis, with respect to one or more business units, divisions, Affiliates, or business segments, and in either absolute terms or relative to the performance of one or more comparable companies or the performance of one or more relevant indices. Unless specified otherwise by the Board (i) in the Award Agreement at the time the Award is granted or (ii) in such other document setting forth the Performance Goals at the time the Performance Goals are established, the Board will appropriately make adjustments in the method of calculating the attainment of Performance Goals for a Performance Period as follows: (1) to exclude restructuring and/or other nonrecurring charges; (2) to exclude exchange rate effects; (3) to exclude the effects of changes to generally accepted accounting principles; (4) to exclude the effects of any statutory adjustments to corporate tax rates; (5) to exclude the effects of items that are “unusual” in nature or occur “infrequently” as determined under generally accepted accounting principles; (6) to exclude the dilutive effects of acquisitions or joint ventures; (7) to assume that any business divested by the Company achieved performance objectives at targeted levels during the balance of a Performance Period following such divestiture; (8) to exclude the effect of any change in the outstanding shares of common stock of the Company by reason of any stock dividend or split, stock repurchase, reorganization, recapitalization, merger, consolidation, spin-off, combination or exchange of shares or other similar corporate change, or any distributions to common stockholders other than regular cash dividends; (9) to exclude the effects of stock based compensation and the award of bonuses under the Company’s bonus plans; (10) to exclude costs incurred in connection with potential acquisitions or divestitures that are required to expense under generally accepted accounting principles; and (11) to exclude the goodwill and intangible asset impairment charges that are required to be recorded under generally accepted accounting principles. In addition, the Board retains the discretion to reduce or eliminate the compensation or economic benefit due upon attainment of Performance Goals and to define the manner of calculating the Performance Criteria it selects to use for such Performance Period. Partial achievement of the specified criteria may result in the payment or vesting corresponding to the degree of achievement as specified in the Award Agreement or the written terms of a Performance Cash Award.

(vv) “Performance Period” means the period of time selected by the Board over which the attainment of one or more Performance Goals will be measured for the purpose of determining a Participant’s right to vesting or exercise of an Award. Performance Periods may be of varying and overlapping duration, at the sole discretion of the Board.

(ww) “Plan” means this Lexeo Therapeutics, Inc. 2025 Inducement Equity Incentive Plan, as amended from time to time.

(xx) “Plan Administrator” means the person, persons, and/or third-party administrator designated by the Company to administer the day to day operations of the Plan and the Company’s other equity incentive programs.

(yy) “Post-Termination Exercise Period” means the period following termination of a Participant’s Continuous Service within which an Option or SAR is exercisable, as specified in Section 4(h).

(zz) “Prospectus” means the document containing the Plan information specified in Section 10(a) of the Securities Act.

(aaa) “Restricted Stock Award” or “RSA” means an Award of shares of Common Stock which is granted pursuant to the terms and conditions of Section 5(a).

(bbb) “Restricted Stock Award Agreement” means a written agreement between the Company and a holder of a Restricted Stock Award evidencing the terms and conditions of a Restricted Stock Award grant. The Restricted Stock Award Agreement includes the Grant Notice for the Restricted Stock Award and the agreement containing the written summary of the general terms and conditions applicable to the Restricted Stock Award and which is provided to a Participant along with the Grant Notice. Each Restricted Stock Award Agreement will be subject to the terms and conditions of the Plan.

(ccc) “RSU Award” or “RSU” means an Award of restricted stock units representing the right to receive an issuance of shares of Common Stock which is granted pursuant to the terms and conditions of Section 5(a).

(ddd) “RSU Award Agreement” means a written agreement between the Company and a holder of a RSU Award evidencing the terms and conditions of a RSU Award grant. The RSU Award Agreement includes the Grant Notice for the RSU Award and the agreement containing the written summary of the general terms and conditions applicable to the RSU Award and which is provided to a Participant along with the Grant Notice. Each RSU Award Agreement will be subject to the terms and conditions of the Plan.

(eee) “Rule 16b-3” means Rule 16b-3 promulgated under the Exchange Act or any successor to Rule 16b-3, as in effect from time to time.

(fff) “Rule 405” means Rule 405 promulgated under the Securities Act.

(ggg) “Section 409A” means Section 409A of the Code and the regulations and other guidance thereunder.

(hhh) “Section 409A Change in Control” means a change in the ownership or effective control of the Company, or in the ownership of a substantial portion of the Company’s assets, as provided in Section 409A(a)(2)(A)(v) of the Code and Treasury Regulations Section 1.409A-3(i)(5) (without regard to any alternative definition thereunder).

(iii) “Securities Act” means the Securities Act of 1933, as amended.

(jjj) “Share Reserve” means the number of shares available for issuance under the Plan as set forth in Section 2(a).

(kkk) “Stock Appreciation Right” or “SAR” means a right to receive the appreciation on Common Stock that is granted pursuant to the terms and conditions of Section 4.

(lll) “SAR Agreement” means a written agreement between the Company and a holder of a SAR evidencing the terms and conditions of a SAR grant. The SAR Agreement includes the Grant Notice for the SAR and the agreement containing the written summary of the general terms and conditions applicable to the SAR and which is provided to a Participant along with the Grant Notice. Each SAR Agreement will be subject to the terms and conditions of the Plan.

(mmm) “Subsidiary” means, with respect to the Company, (i) any corporation of which more than 50% of the outstanding capital stock having ordinary voting power to elect a majority of the board of directors of such corporation (irrespective of whether, at the time, stock of any other class or classes of such corporation will have or might have voting power by reason of the happening of any contingency) is at the time, directly or indirectly, Owned by the Company, and (ii) any partnership, limited liability company or other entity in which the Company has a direct or indirect interest (whether in the form of voting or participation in profits or capital contribution) of more than 50%.

(nnn) “Trading Policy” means the Company’s policy permitting certain individuals to sell Company shares only during certain "window" periods and/or otherwise restricts the ability of certain individuals to transfer or encumber Company shares, as in effect from time to time.

(ooo) “Unvested Non-Exempt Award” means the portion of any Non-Exempt Award that had not vested in accordance with its terms upon or prior to the date of any Corporate Transaction.

(ppp) “Vested Non-Exempt Award” means the portion of any Non-Exempt Award that had vested in accordance with its terms upon or prior to the date of a Corporate Transaction.

Lexeo Therapeutics, Inc. Stock Option Grant Notice (2025 Inducement Equity Incentive Plan)

Lexeo Therapeutics, Inc. (the “Company”), pursuant to its 2025 Inducement Equity Incentive Plan (the “Plan”), has granted to you (“Optionholder”) an option to purchase the number of shares of the Common Stock set forth below (the “Option”). Your Option is subject to all of the terms and conditions as set forth herein and in the Plan, and the Stock Option Agreement and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Stock Option Agreement shall have the meanings set forth in the Plan or the Stock Option Agreement, as applicable.

Optionholder:
Date of Grant:
Vesting Commencement Date:
Number of Shares of Common Stock Subject to Option:
Exercise Price (Per Share):
Total Exercise Price:
Expiration Date:

Type of Grant: Nonstatutory Stock Option

Exercise and

Vesting Schedule: Subject to the Optionholder’s Continuous Service through each applicable vesting date, the Option will vest as follows:

[ ]

Optionholder Acknowledgements: By your signature below or by electronic acceptance or authentication in a form authorized by the Company, you understand and agree that:

 The Option is governed by this Stock Option Grant Notice, and the provisions of the Plan and the Stock Option Agreement and the Notice of Exercise, all of which are made a part of this document. Unless otherwise provided in the Plan, this Grant Notice and the Stock Option Agreement (together, the “Option Agreement”) may not be modified, amended or revised except in a writing signed by you and a duly authorized officer of the Company.

 You consent to receive this Grant Notice, the Stock Option Agreement, the Plan, the Prospectus and any other Plan-related documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company.

 You have read and are familiar with the provisions of the Plan, the Stock Option Agreement, the Notice of Exercise and the Prospectus. In the event of any conflict between the provisions in this Grant Notice, the Option Agreement, the Notice of Exercise, or the Prospectus and the terms of the Plan, the terms of the Plan shall control.

 The Option Agreement sets forth the entire understanding between you and the Company regarding the acquisition of Common Stock and supersedes all prior oral and written agreements, promises and/or representations on that subject with the exception of other equity awards previously granted to you and any written employment agreement, offer letter, severance agreement, written severance plan or policy, or other written agreement between the Company and you in each case that specifies the terms that should govern this Option.

 Counterparts may be delivered via facsimile, electronic mail (including pdf or any electronic signature complying with the U.S. federal ESIGN Act of 2000, Uniform Electronic Transactions Act or other applicable law) or other transmission method and any counterpart so delivered will be deemed to have been duly and validly delivered and be valid and effective for all purposes.

Lexeo Therapeutics, Inc.		Optionholder:
By:
	Signature	Signature
Title:		Date:
Date:

Attachments: Stock Option Agreement, 2025 Inducement Equity Incentive Plan, Notice of Exercise

Attachment I

Stock Option Agreement

Lexeo Therapeutics, Inc. 2025 Inducement Equity Incentive Plan

Stock Option Agreement

As reflected by your Stock Option Grant Notice (“Grant Notice”), Lexeo Therapeutics, Inc. (the “Company”) has granted you an option under its 2025 Inducement Equity Incentive Plan (the “Plan”) to purchase a number of shares of Common Stock at the exercise price indicated in your Grant Notice (the “Option”). Capitalized terms not explicitly defined in this Agreement but defined in the Grant Notice or the Plan shall have the meanings set forth in the Grant Notice or Plan, as applicable. The terms of your Option as specified in the Grant Notice and this Stock Option Agreement constitute your Option Agreement.

The general terms and conditions applicable to your Option are as follows:

1. Governing Plan Document. Your Option is subject to all the provisions of the Plan, including but not limited to the provisions in:

(a) Section 6 regarding the impact of a Capitalization Adjustment, dissolution, liquidation, or Corporate Transaction on your Option;

(b) Section 9(e) regarding the Company’s retained rights to terminate your Continuous Service notwithstanding the grant of the Option; and

(c) Section 8(c) regarding the tax consequences of your Option.

Your Option is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and adopted pursuant to the Plan. In the event of any conflict between the Option Agreement and the provisions of the Plan, the provisions of the Plan shall control.

2. Vesting. Your Option will vest as provided in your Grant Notice, subject to the provisions contained herein and the terms of the Plan. Vesting will cease upon the termination of your Continuous Service.

3. Exercise.

(a) You may generally exercise the vested portion of your Option for whole shares of Common Stock at any time during its term by delivery of payment of the exercise price and applicable withholding taxes and other required documentation to the Plan Administrator in accordance with the exercise procedures established by the Plan Administrator, which may include an electronic submission. Please review Sections 4(i), 4(j) and 7(b)(v) of the Plan, which may restrict or prohibit your ability to exercise your Option during certain periods.

(b) To the extent permitted by Applicable Law, you may pay your Option exercise price as follows:

(i) cash, check, bank draft or money order;

(ii) pursuant to a “cashless exercise” program as further described in Section 4(c)(ii) of the Plan if at the time of exercise the Common Stock is publicly traded;

(iii) subject to Company and/or Committee consent at the time of exercise, by delivery of previously owned shares of Common Stock as further described in Section 4(c)(iii) of the Plan; or

(iv) subject to Company and/or Committee consent at the time of exercise, by a “net exercise” arrangement as further described in Section 4(c)(iv) of the Plan.

(c) By accepting your Option, you agree that you will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held by you, for a period of 180 days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this Section 3(c) will prevent the exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of Common Stock until the end of such period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 3(c). The underwriters of the Company’s stock are intended third party beneficiaries of this Section 3(c) and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto.

4. Term. You may not exercise your Option before the commencement of its term or after its term expires. The term of your Option commences on the Date of Grant and expires upon the earliest of the following:

(a) immediately upon the termination of your Continuous Service for Cause;

(b) three months after the termination of your Continuous Service for any reason other than Cause, Disability or death;

(c) 12 months after the termination of your Continuous Service due to your Disability;

(d) 18 months after your death if you die during your Continuous Service;

(e) immediately upon a Corporate Transaction if the Board has determined that the Option will terminate in connection with a Corporate Transaction,

(f) the Expiration Date indicated in your Grant Notice; or

(g) the day before the 10th anniversary of the Date of Grant.

Notwithstanding the foregoing, if you die during the period provided in Section 4(b) or 4(c) above, the term of your Option shall not expire until the earlier of (i) 18 months after your death, (ii) upon any termination of the Option in connection with a Corporate Transaction, (iii) the Expiration Date indicated in your Grant Notice, or (iv) the day before the tenth anniversary of the Date of Grant. Additionally, the Post-Termination Exercise Period of your Option may be extended as provided in Section 4(i) of the Plan.

5. Withholding Obligations. As further provided in Section 8 of the Plan: (a) you may not exercise your Option unless the applicable tax withholding obligations are satisfied, and (b) at the time you exercise your Option, in whole or in part, or at any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “cashless exercise” pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations, if any, which arise in connection with the exercise of your Option in accordance with the withholding procedures established by the Company. Accordingly, you may not be able to exercise your Option even though the Option is vested, and the Company shall have no obligation to issue shares of Common Stock subject to your Option, unless and until such obligations are satisfied. In the event that the amount of the Company’s withholding obligation in connection with your Option was greater than the amount actually withheld by the Company, you agree to indemnify and hold the Company harmless from any failure by the Company to withhold the proper amount.

6. [RESERVED].

7. Transferability. Except as otherwise provided in Section 4(e) of the Plan, your Option is not transferable, except by will or by the applicable laws of descent and distribution, and is exercisable during your life only by you.

8. Corporate Transaction. Your Option is subject to the terms of any agreement governing a Corporate Transaction involving the Company, including, without limitation, a provision for the appointment of a stockholder representative that is authorized to act on your behalf with respect to any escrow, indemnities and any contingent consideration.

9. No Liability for Taxes. As a condition to accepting the Option, you hereby (a) agree to not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from the Option or other Company compensation and (b) acknowledge that you were advised to consult with your own personal tax, financial and other legal advisors regarding the tax consequences of the Option and have either done so or knowingly and voluntarily declined to do so. Additionally, you acknowledge that the Option is exempt from Section 409A only if the exercise price is at least equal to the “fair market value” of the Common Stock on the date of grant as determined by the Internal Revenue Service and there is no other impermissible deferral of compensation associated with the Option. Additionally, as a condition to accepting the Option, you agree not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates in the event that the Internal Revenue Service asserts that such exercise is less than the “fair market value” of the Common Stock on the date of grant as subsequently determined by the Internal Revenue Service.

10. Severability. If any part of this Option Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Option Agreement or the Plan not declared to be unlawful or invalid. Any Section of this Option Agreement (or part of such a Section) so declared to be unlawful or invalid will, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid

11. Other Documents. You hereby acknowledge receipt of or the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Prospectus. In addition, you acknowledge receipt of the Company’s Trading Policy.

12. Questions. If you have questions regarding these or any other terms and conditions applicable to your Option, including a summary of the applicable federal income tax consequences please see the Prospectus.

* * * *

Attachment II

2025 Inducement Equity Incentive Plan

Attachment III

Notice of Exercise

Lexeo Therapeutics, Inc.

(2025 Inducement Equity Incentive Plan)

NOTICE OF EXERCISE

Lexeo Therapeutics, Inc.

345 Park Avenue South, 6th Floor

New York, NY 10010

Date of Exercise: _______________

This constitutes notice to Lexeo Therapeutics, Inc. (the “Company”) that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) by exercising my Option for the price set forth below. Capitalized terms not explicitly defined in this Notice of Exercise but defined in the Grant Notice, Option Agreement or 2025 Inducement Equity Incentive Plan (the “Plan”) shall have the meanings set forth in the Grant Notice, Option Agreement or Plan, as applicable. Use of certain payment methods is subject to Company and/or Committee consent and certain additional requirements set forth in the Option Agreement and the Plan.

Type of option:			Nonstatutory
Date of Grant:
Number of Shares as to which Option is Exercised:
Certificates to be issued in name of:
Total exercise price:			$
	Cash, check, bank draft or money order delivered herewith:		$
	Value of	Shares
	delivered herewith:		$
	Regulation T Program (cashless exercise)		$
	Value of	Shares
	pursuant to net exercise:		$

By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the terms of the Plan, and (ii) to satisfy the tax withholding obligations, if any, relating to the exercise of this Option as set forth in the Option Agreement.

I further agree that I will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company that I hold, for a period of 180 days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar rules or regulation (the “Lock-Up Period”); provided, however, that nothing contained in this paragraph will prevent the exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. I further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing or that are necessary to give further effect thereto. I further agree that in order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to shares of Common Stock that I hold until the end of such period. I also agree that any transferee of any shares of Common Stock (or other securities) of the Company that I hold will be bound by this paragraph. The underwriters of the Company’s stock are intended third party beneficiaries of this paragraph and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto.

Very truly yours,

Lexeo Therapeutics, Inc. RSU Award Grant Notice (2025 Inducement Equity Incentive Plan)

Lexeo Therapeutics, Inc. (the “Company”) has awarded to you (the “Participant”) the number of restricted stock units specified and on the terms set forth below in consideration of your services (the “RSU Award”). Your RSU Award is subject to all of the terms and conditions as set forth herein and in the Company’s 2025 Inducement Equity Incentive Plan (the “Plan”) and the Award Agreement (the “Agreement”), which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Agreement shall have the meanings set forth in the Plan or the Agreement.

Participant:
Date of Grant:
Vesting Commencement Date:
Number of Restricted Stock Units:

Vesting Schedule: Subject to the Participant’s Continuous Service through each applicable vesting date, the RSU Award will vest as follows:

[ ]	.

Issuance Schedule: One share of Common Stock will be issued for each restricted stock unit which vests at the time set forth in Section 6 of the Agreement.

Participant Acknowledgements: By your signature below or by electronic acceptance or authentication in a form authorized by the Company, you understand and agree that:

 The RSU Award is governed by this RSU Award Grant Notice (the “Grant Notice”), and the provisions of the Plan and the Agreement, all of which are made a part of this document. Unless otherwise provided in the Plan, this Grant Notice and the Agreement (together, the “RSU Award Agreement”) may not be modified, amended or revised except in a writing signed by you and a duly authorized officer of the Company.

 You have read and are familiar with the provisions of the Plan, the RSU Award Agreement and the Prospectus. In the event of any conflict between the provisions in the RSU Award Agreement, or the Prospectus and the terms of the Plan, the terms of the Plan shall control.

 The RSU Award Agreement sets forth the entire understanding between you and the Company regarding the acquisition of Common Stock and supersedes all prior oral and written agreements, promises and/or representations on that subject with the exception of: (i) other equity awards previously granted to you, and (ii) any written employment agreement, offer letter, severance agreement, written severance plan or policy, or other written agreement between the Company and you in each case that specifies the terms that should govern this RSU Award.

Lexeo Therapeutics, Inc.		Participant:
By:
	Signature	Signature
Title:		Date:
Date:

Attachments: RSU Award Agreement, 2025 Inducement Equity Incentive Plan

Lexeo Therapeutics, Inc.

2025 Inducement Equity Incentive Plan

Award Agreement (RSU Award)

As reflected by your Restricted Stock Unit Grant Notice (“Grant Notice”) Lexeo Therapeutics, Inc. (the “Company”) has granted you a RSU Award under its 2025 Inducement Equity Incentive Plan (the “Plan”) for the number of restricted stock units as indicated in your Grant Notice (the “RSU Award”). The terms of your RSU Award as specified in this Award Agreement for your RSU Award (the “Agreement”) and the Grant Notice constitute your “RSU Award Agreement”. Defined terms not explicitly defined in this Agreement but defined in the Grant Notice or the Plan shall have the same definitions as in the Grant Notice or Plan, as applicable.

The general terms applicable to your RSU Award are as follows:

1. Governing Plan Document. Your RSU Award is subject to all the provisions of the Plan, including but not limited to the provisions in:

(a) Section 6 of the Plan regarding the impact of a Capitalization Adjustment, dissolution, liquidation, or Corporate Transaction on your RSU Award;

(b) Section 9(e) of the Plan regarding the Company’s retained rights to terminate your Continuous Service notwithstanding the grant of the RSU Award; and

(c) Section 8(c) of the Plan regarding the tax consequences of your RSU Award.

Your RSU Award is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and adopted pursuant to the Plan. In the event of any conflict between the RSU Award Agreement and the provisions of the Plan, the provisions of the Plan shall control.

2. Grant of the RSU Award. This RSU Award represents your right to be issued on a future date the number of shares of the Company’s Common Stock that is equal to the number of restricted stock units indicated in the Grant Notice as modified to reflect any Capitalization Adjustment and subject to your satisfaction of the vesting conditions set forth therein (the “Restricted Stock Units”). Any additional Restricted Stock Units that become subject to the RSU Award pursuant to Capitalization Adjustments as set forth in the Plan and the provisions of Section 4 below, if any, shall be subject, in a manner determined by the Board, to the same forfeiture restrictions, restrictions on transferability, and time and manner of delivery as applicable to the other Restricted Stock Units covered by your RSU Award.

3. Vesting. Your Restricted Stock Units will vest, if at all, in accordance with the vesting schedule provided in the Grant Notice, subject to the provisions contained herein and the terms of the Plan. Vesting will cease upon the termination of your Continuous Service.

4. Dividends. You may become entitled to receive payments equal to any cash dividends and other distributions paid with respect to a corresponding number of shares of Common Stock to be issued in respect of the Restricted Stock Units covered by your RSU Award. Any such dividends or distributions shall be subject to the same forfeiture restrictions as apply to the Restricted Stock Units and shall be paid at the same time that the corresponding shares are issued in respect of your vested Restricted Stock Units, provided, however that to the extent any such dividends or distributions are paid in shares of Common Stock, then you will automatically be granted a corresponding number of additional Restricted Stock Units subject to the RSU Award (the “Dividend Units”), and further provided that such Dividend Units shall be subject to the same forfeiture restrictions and restrictions on transferability, and same timing requirements for issuance of shares, as apply to the Restricted Stock Units subject to the RSU Award with respect to which the Dividend Units relate.

5. Withholding Obligations. As further provided in Section 8 of the Plan, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for, any sums required to satisfy the federal, state, local and foreign tax withholding obligations, if any, which arise in connection with your RSU Award (the “Withholding Obligation”) in accordance with the withholding procedures established by the Company. Unless the Withholding Obligation is satisfied, the Company shall have no obligation to deliver to you any Common Stock in respect of the RSU Award. In the event the Withholding Obligation of the Company arises prior to the delivery to you of Common Stock or it is determined after the delivery of Common Stock to you that the amount of the Withholding Obligation was greater than the amount withheld by the Company, you agree to indemnify and hold the Company harmless from any failure by the Company to withhold the proper amount.

6. Date of Issuance.

(a) The issuance of shares in respect of the Restricted Stock Units is intended to comply with Treasury Regulations Section 1.409A-1(b)(4) and will be construed and administered in such a manner. Subject to the satisfaction of the Withholding Obligation, if any, in the event one or more Restricted Stock Units vests, the Company shall issue to you one (1) share of Common Stock for each Restricted Stock Unit (subject to any adjustment under Section 4 above, and subject to any different provisions in the Grant Notice) that vests on the applicable vesting date(s) or on a later date as determined by the Company but in no event later than the Issuance Deadline (as defined below).

(b) In addition, the following provisions shall apply to the extent applicable at a vesting date when shares of Common Stock are registered under the Securities Act, unless otherwise determined by the Company. If:

(i) the applicable vest date does not occur (1) during an “open window period” applicable to you, as determined by the Company in accordance with the Company’s then-effective policy on trading in Company securities, or (2) on a date when you are otherwise permitted to sell shares of Common Stock on an established stock exchange or stock market (including but not limited to under a previously established written trading plan that meets the requirements of Rule 10b5-1 under the Exchange Act and was entered into in compliance with the Company’s policies (a “10b5-1 Arrangement”) or under such other policy expressly approved by the Company), and

(ii) either (1) a Withholding Obligation does not apply, or (2) the Company decides, prior to the applicable vest date, (A) not to satisfy the Withholding Obligation by withholding shares of Common Stock from the shares otherwise due to you under this Award, and (B) not to permit you to enter into a “same day sale” commitment with a broker-dealer (including but not limited to a commitment under a 10b5-1 Arrangement) and (C) not to permit you to pay your Withholding Obligation in cash, then the shares that would otherwise be issued to you on the applicable vest date will not be delivered on such applicable vest date and will instead be delivered on the first business day when you are not prohibited from selling shares of the Company’s Common Stock in the open public market or on such other date determined by the Company, but in no event later than the Issuance Deadline.

The “Issuance Deadline” means (a) December 31 of the calendar year in which the applicable vest date occurs (that is, the last day of your taxable year in which the applicable vest date occurs), or (b) if and only if permitted in a manner that complies with Treasury Regulations Section 1.409A-1(b)(4), no later than the date that is the 15th day of the third calendar month of the applicable year following the year in which the shares of Common Stock issuable as a result of the applicable vest date under this Award are no longer subject to a “substantial risk of forfeiture” within the meaning of Treasury Regulations Section 1.409A-1(d).

(c) To the extent the RSU Award is a Non-Exempt Award, the provisions of Section 11 of the Plan shall apply.

7. Lock-Up Period. By accepting your RSU Award, you agree that you will not sell, dispose of, transfer, make any short sale of, grant any option for the purchase of, or enter into any hedging or similar transaction with the same economic effect as a sale with respect to any shares of Common Stock or other securities of the Company held by you, for a period of one hundred eighty (180) days following the effective date of a registration statement of the Company filed under the Securities Act or such longer period as the underwriters or the Company will request to facilitate compliance with FINRA Rule 2241 or any successor or similar rules or regulation (the “Lock-Up Period”);

provided, however, that nothing contained in this Section 7 will prevent the exercise of a repurchase option, if any, in favor of the Company during the Lock-Up Period. You further agree to execute and deliver such other agreements as may be reasonably requested by the Company or the underwriters that are consistent with the foregoing or that are necessary to give further effect thereto. In order to enforce the foregoing covenant, the Company may impose stop-transfer instructions with respect to your shares of Common Stock until the end of such period. You also agree that any transferee of any shares of Common Stock (or other securities) of the Company held by you will be bound by this Section 7. The underwriters of the Company’s stock are intended third party beneficiaries of this Section 7 and will have the right, power and authority to enforce the provisions hereof as though they were a party hereto.

8. Transferability. Except as otherwise provided in the Plan, your RSU Award is not transferable, except by will or by the applicable laws of descent and distribution.

9. Corporate Transaction. Your RSU Award is subject to the terms of any agreement governing a Corporate Transaction involving the Company, including, without limitation, a provision for the appointment of a stockholder representative that is authorized to act on your behalf with respect to any escrow, indemnities and any contingent consideration.

10. No Liability for Taxes. As a condition to accepting the RSU Award, you hereby (a) agree to not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from the RSU Award or other Company compensation and (b) acknowledge that you were advised to consult with your own personal tax, financial and other legal advisors regarding the tax consequences of the RSU Award and have either done so or knowingly and voluntarily declined to do so.

11. Severability. If any part of this Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Agreement or the Plan not declared to be unlawful or invalid. Any Section of this Agreement (or part of such a Section) so declared to be unlawful or invalid will, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid.

12. Other Documents. You hereby acknowledge receipt of or the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Prospectus. In addition, you acknowledge receipt of the Company’s Trading Policy.

13. Questions. If you have questions regarding these or any other terms and conditions applicable to your RSU Award, including a summary of the applicable federal income tax consequences please see the Prospectus.

EX-10.6

Exhibit 10.6

EMPLOYMENT AGREEMENT

for

Louis Tamayo

This Employment Agreement (the “Agreement”) is made between Lexeo Therapeutics, Inc. (the “Company”) and Louis Tamayo. (the “Executive”) (collectively, the “Parties”).

Whereas, the Company desires for Executive to provide services to the Company, and wishes to provide Executive with certain compensation and benefits in return for such employment services; and

Whereas, Executive wishes to be employed by the Company and to provide personal services to the Company in return for certain compensation and benefits;

Now, Therefore, in consideration of the mutual promises and covenants contained herein and for other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Parties hereto agree as follows:

• Employment by the Company.

• Position. Beginning August 15, 2025, Executive shall serve as the Company’s Chief Financial Officer. During the term of Executive’s employment with the Company, Executive will devote Executive’s best efforts and substantially all of Executive’s business time and attention to the business of the Company, except for approved time off permitted by the Company’s general employment policies.

• Duties and Location. Executive shall perform such duties incident to the position held by Executive, including without limitation such duties and responsibilities as may be assigned to Executive by the Chief Executive Officer (“CEO”), to whom Executive will report. Executive shall work in the Company’s New York City office as needed and requested by the Company, and Executive will be permitted to work remotely from his home office when not in the New York City office. The Company reserves the right, at the Board’s discretion, to reasonably require Executive to perform Executive’s duties at places other than Executive’s primary office location from time to time, and to require reasonable business travel. The Company may modify Executive’s job title and duties as it deems necessary and appropriate in light of the Company’s needs and interests from time to time.

• Policies and Procedures. The employment relationship between the Parties shall be governed by the general employment policies and practices of the Company, except that when the terms of this Agreement differ from or are in conflict with the Company’s general employment policies or practices, this Agreement shall control.

• Indemnification. The Executive shall be provided indemnification coverage under the Company’s Directors and Officers (D&O) liability insurance policies to the same extent as directors and other executive officers of the Company.

• Compensation.

• Salary. For services to be rendered hereunder, Executive shall receive a base salary at the rate of $480,000 per year (the “Base Salary”), subject to standard payroll deductions and withholdings and payable in accordance with the Company’s regular payroll schedule. The Base Salary is subject to periodic review and modification by the CEO and the Board (or the Compensation Committee of the Board), from time to time, at their sole discretion.

• Annual Cash Bonus. Executive will be eligible for an annual discretionary cash bonus target of 40% of Executive’s Base Salary (the “Annual Bonus”). Whether Executive receives an Annual Bonus for any given year, and the amount of any such Annual Bonus, will be determined by the CEO and the Board (or the Compensation Committee of the Board) in their sole discretion based upon the Company’s performance and Executive’s achievement of individual objectives and milestones to be determined on an annual basis. Any Annual Bonus that is awarded will be paid within the first ninety (90) days of the calendar year following the applicable bonus year. Executive will not be eligible for, and will not earn, any Annual Bonus if Executive’s employment terminates for any reason, or if Executive or the Company has given notice of the termination of Executive’s employment, before the payment date, except as expressly provided for in Section 5.5 herein.

• Equity Awards. Subject to the approval of the Company’s Compensation Committee of the Board of Directors (the “Committee”), you will be granted a mix of equity awards as follows:

• An option to purchase 280,000 shares of the Company’s Common Stock (the “Option”). The Option will vest and become exercisable over 4 years at the rate of 25% of the total number of Option shares on the 1-year anniversary of your start date of employment with the Company (the “Anniversary Date”) and 1/48th of the total number of Option shares at the end of each month commencing after the Anniversary Date, subject to your continuous service with the Company through each vesting date. The exercise price per share of the Option will be equal to the fair market value per share of the Company’s Common Stock on the date the Option is granted, as determined by the Board in good faith. There is no guarantee that the Internal Revenue Service will agree with this value, and you should consult with an accountant or tax professional if you have questions regarding this value and potential tax implications.

• 45,000 restricted stock units of the Company’s Common Stock (the “RSUs”). The RSUs will vest over a period of approximately 4 years. RSUs for the Company will generally vest on specific dates each quarter for the entire Company. The vesting start date of your RSUs will be the Company RSU vesting date that occurs on or after your start date. The RSUs will vest as to 25% of the total number of RSUs on the 1- year anniversary of your RSU vesting start date (the “RSU Anniversary Date”) and 1/16th of the total number of RSU shares at the end of each quarter (i.e., three-month period) commencing after the RSU Anniversary Date, subject to your continuous service with the Company through each vesting date.

• Standard Company Benefits. Executive shall be entitled to participate in all employee benefit programs for which Executive is eligible under the terms and conditions of the benefit plans that may be in effect from time to time and provided by the Company to its employees, subject to the eligibility criteria, rules, plan provisions and regulations applicable to such plans, except to the extent that participation in such plans or programs would result in duplication of benefits provided hereunder. The Company reserves the right to cancel or change the benefit plans or programs it offers to its employees at any time, in its sole discretion.

• Expenses. The Company will reimburse Executive for reasonable travel, entertainment or other expenses incurred by Executive in furtherance or in connection with the performance of Executive’s duties hereunder, subject to, and in accordance with, the Company’s expense reimbursement policy as in effect from time to time.

• Termination of Employment; Severance

• At-Will Employment. Executive’s employment relationship is at-will. Either Executive or the Company may terminate the employment relationship at any time, with or without cause or advance notice.

• Termination Based on Death or Disability. In the event of the Executive’s death, the Executive’s employment with the Company shall terminate automatically. The Company, in its discretion, shall have the right to terminate the Executive’s employment because of the Executive’s Disability during the Employment Period, subject to applicable law. For purposes of this Agreement, “Disability” means that the Executive has been unable, for 60 consecutive days, or for any period aggregating 90 business days in any consecutive 180 day period, as the case may be, to perform a substantial portion of the Executive’s duties under this Agreement, as a result of physical or mental impairment, illness or injury, as determined by a medical doctor reasonably selected by the Company and approved by the Executive, such approval not to be unreasonably withheld, delayed or conditioned. Such determination shall be deemed to be conclusive for all purposes of this Section 5.2. In connection with the foregoing, the Executive shall cooperate with such medical doctor, including without limitation, by submitting to such medical tests and examinations as may be requested by the medical doctor. A termination of the Executive’s employment by the Company for Disability shall be communicated to the Executive by written notice upon the expiration of the applicable period and shall be effective on the 30th day after receipt of such notice by the Executive (the “Disability Effective Date”), unless the Executive returns to satisfactory full-time performance of the Executive’s previous duties before the Disability Effective Date. In the event the Executive’s employment is terminated due to death or Disability, the Company shall have no further obligations to the Executive hereunder, except the Company shall pay to the Executive (or, in the event of death, to the Executive’s estate) any (i) Base Salary earned or payable but unpaid to the Executive through the Date of Termination, (ii) reimbursable business expenses incurred but unpaid through the Date of Termination (subject to Company’s applicable expense policies, including submission of all required documentation), and (iii) any other amounts or benefits required by applicable law.

• Termination Without Cause; Resignation for Good Reason.

• The Company may terminate Executive’s employment with the Company at any time without Cause (as defined below). Further, Executive may resign at any time for Good Reason (as defined below).

• In the event Executive’s employment with the Company is terminated by the Company without Cause, or Executive resigns for Good Reason, then provided such termination constitutes a “separation from service” (as defined under Treasury Regulation Section 1.409A-1(h), without regard to any alternative definition thereunder, a “Separation from Service”), and provided that Executive remains in compliance with the terms of this Agreement, the Company shall provide Executive with the following severance benefits:

• The Company shall pay Executive, as severance, twelve (12) months of Executive’s base salary in effect as of the date of Executive’s employment termination, subject to standard payroll deductions and withholdings (the “Severance”). The Severance will be paid in a single lump sum on or about the Company’s first regular payroll date following the 60th day after Executive’s Separation from Service.

• Provided Executive timely elects continued coverage under COBRA, the Company shall pay Executive’s COBRA premiums to continue Executive’s coverage (including coverage for eligible dependents, if applicable) (“COBRA Premiums”) through the period (the “COBRA Premium Period”) starting on Executive’s Separation from Service and ending on the earliest to occur of: (i) twelve (12) months following Executive’s Separation from Service; (ii) the date Executive becomes eligible for group health insurance coverage through a new employer; or (iii) the date Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination. In the event Executive becomes covered under another employer’s group health plan or otherwise ceases to be eligible for COBRA during the COBRA Premium Period, Executive must immediately notify the Company of such event. Notwithstanding the foregoing, if the Company determines, in its sole discretion, that it cannot pay the COBRA Premiums without a substantial risk of violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company instead shall pay to Executive, on the first day of each calendar month, a fully taxable cash payment equal to the applicable COBRA premiums for that month (including premiums for Executive and Executive’s eligible dependents who have elected and remain enrolled in such COBRA coverage), subject to applicable tax withholdings (such amount, the “Special Cash Payment”), for the remainder of the COBRA Premium Period. Executive may, but is not obligated to, use the Special Cash Payment toward the cost of COBRA premiums.

• Termination for Cause; Resignation Without Good Reason; Death or Disability.

• The Company may terminate Executive’s employment with the Company at any time for Cause. Further, Executive may resign at any time without Good Reason. Executive’s employment with the Company may also be terminated due to Executive’s death or disability.

• If Executive resigns without Good Reason, or the Company terminates Executive’s employment for Cause, or upon Executive’s death or disability, then (i) Executive will no longer vest in the Option and any other stock options held by the Executive, (ii) all payments of compensation by the Company to Executive hereunder will terminate immediately (except as to amounts already earned), and (c) Executive will not be entitled to any severance benefits, including (without limitation) the Severance, COBRA Premiums, Special Cash Payments, unless required by law.

• Termination in Connection with Change in Control. If the Company terminates Executive’s employment no more than three (3) months prior to a Change in Control (as defined herein) or within twelve (12) months following a Change in Control, Executive shall be entitled to receive the following severance benefits:

• The Company shall pay Executive, as severance, twelve (12) months of Executive’s base salary in effect as of the date of Executive’s employment termination, subject to standard payroll deductions and withholdings (the “CIC Severance”). The CIC Severance will be paid in a single lump sum on or about the Company’s first regular payroll date following the 60th day after Executive’s Separation from Service.

• Provided Executive timely elects continued coverage under COBRA, the Company shall pay Executive’s COBRA premiums to continue Executive’s coverage (including coverage for eligible dependents, if applicable) (“CIC COBRA Premiums”) through the period (the “CIC COBRA Premium Period”) starting on Executive’s Separation from Service and ending on the earliest to occur of: (i) twelve (12) months following Executive’s Separation from Service; (ii) the date Executive becomes eligible for group health insurance coverage through a new employer; or (iii) the date Executive ceases to be eligible for COBRA continuation coverage for any reason, including plan termination. In the event Executive becomes covered under another employer’s group health plan or otherwise ceases to be eligible for COBRA during the CIC COBRA Premium Period, Executive must immediately notify the Company of such event. Notwithstanding the foregoing, if the Company determines, in its sole discretion, that it cannot pay the CIC COBRA Premiums without a substantial risk of violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), the Company instead shall pay to Executive, on the first day of each calendar month, a fully taxable cash payment equal to the applicable COBRA premiums for that month (including premiums for Executive and Executive’s eligible dependents who have elected and remain enrolled in such COBRA coverage), subject to applicable tax withholdings (such amount, the “CIC Special Cash Payment”), for the remainder of the CIC COBRA Premium Period. Executive may, but is not obligated to, use such CIC Special Cash Payments toward the cost of COBRA premiums.

• The Company shall pay Executive, as further severance, a lump sum amount equal to Executive’s full bonus target for the calendar year in which the Change in Control occurs (the “CIC Bonus Payment”), to be paid no later than thirty (30) days following Executive’s Separation from Service.

• The Company shall accelerate the vesting of any shares, options, or other equity grants then unvested and outstanding as of the Executive’s Separation from Service, such that Executive will thereafter be 100% vested in any shares, options, or other equity grants awarded by the Company to Executive during Executive’s employment with the Company (the “Vesting Acceleration”).

• Conditions to Receipt of Severance, COBRA Premiums, and Special Cash Payments. The receipt of the Severance, CIC Severance, COBRA Premiums, CIC COBRA Premiums, Special Cash Payments, CIC Special Cash Payments, CIC Bonus Payment, and Vesting Acceleration (collectively, the “Severance Benefits”) will be subject to Executive signing and not revoking a separation agreement and release of claims in a form satisfactory to the Company (the “Separation Agreement”) within a time period specified by the Company, in its sole discretion. No Severance Benefits will be paid or provided until the Separation Agreement becomes effective. Executive shall also resign from all positions and terminate any relationships as an employee, advisor, officer or director with the Company and any of its affiliates, each effective on the date of termination.

• Section 409A. It is intended that all of the severance benefits and other payments payable under this Agreement satisfy, to the greatest extent possible, the exemptions from the application of Code Section 409A provided under Treasury Regulations 1.409A-1(b)(4), 1.409A-1(b)(5) and 1.409A-1(b)(9), and this Agreement will be construed to the greatest extent possible as consistent with those provisions, and to the extent not so exempt, this Agreement (and any definitions hereunder) will be construed in a manner that complies with Section 409A. For purposes of Code Section 409A (including, without limitation, for purposes of Treasury Regulation Section 1.409A-2(b)(2)(iii)), Executive’s right to receive any installment payments under this Agreement (whether severance payments, reimbursements or otherwise) shall be treated as a right to receive a series of separate payments and, accordingly, each installment payment hereunder shall at all times be considered a separate and distinct payment. Notwithstanding any provision to the contrary in this Agreement, if Executive is deemed by the Company at the time of Executive’s Separation from Service to be a “specified employee” for purposes of Code Section 409A(a)(2)(B)(i), and if any of the payments upon Separation from Service set forth herein and/or under any other agreement with the Company are deemed to be “deferred compensation”, then to the extent delayed commencement of any portion of such payments is required in order to avoid a prohibited distribution under Code Section 409A(a)(2)(B)(i) and the related adverse taxation under Section 409A, such payments shall not be provided to Executive prior to the earliest of (i) the expiration of the six-month period measured from the date of Executive’s Separation from Service with the Company, (ii) the date of Executive’s death or (iii) such earlier date as permitted under Section 409A without the imposition of adverse taxation. Upon the first business day following the expiration of such applicable Code Section 409A(a)(2)(B)(i) period, all payments deferred pursuant to this Paragraph shall be paid in a lump sum to Executive, and any remaining payments due shall be paid as otherwise provided herein or in the applicable agreement. No interest shall be due on any amounts so deferred.

• Definitions.

• Cause. For purposes of this Agreement, “Cause” for termination will mean: (a) Executive’s conviction for, or entry of a guilty plea or plea of nolo contendere for, any felony or crime involving dishonesty; (b) Executive’s participation in any fraud against the Company; (c) material breach of Executive’s fiduciary duties to the Company after written notice from the Board describing the events leading to termination for Cause and 15 days to cure (if deemed curable); (d) persistent unsatisfactory performance of Executive’s job duties after written notice from the Board describing the events leading to termination for Cause and 15 days to cure (if deemed curable); (e) Executive’s intentional damage to any property of the Company; (f) Executive’s misconduct, or other material violation of Company written policy that causes harm after written notice from the Board describing the events leading to termination for Cause and 15 days to cure (if deemed curable); (g) Executive’s material breach of any written agreement with the Company after written notice from the Board describing the events leading to termination for Cause and 15 days to cure (if deemed curable); and (h) conduct by Executive which in the good faith and reasonable determination of the Board demonstrates gross unfitness to serve, including but not limited to conduct involving moral turpitude, corruption, dishonesty, or other conduct that harms the Company’s reputation or prospects.

• Good Reason. For purposes of this Agreement, Executive shall have “Good Reason” for resignation from employment with the Company if any of the following actions are taken by the Company without Executive’s prior written consent: (a) a material reduction in Executive’s base salary, which the parties agree is a reduction of at least 10% of Executive’s base salary (unless pursuant to a salary reduction program applicable generally to the Company’s similarly situated executive employees); (b) a material reduction in Executive’s duties (including responsibilities and/or authorities), provided, however, that a change in job position shall not be deemed a “material reduction” in and of itself unless Executive’s new duties are materially reduced from the prior duties; or (c) relocation of Executive’s principal place of employment to a place that increases Executive’s one-way commute by more than sixty (60) miles as compared to Executive’s then-current principal place of employment immediately prior to such relocation. In order to resign for Good Reason, Executive must provide written notice to the Board within 30 days after the first occurrence of the event giving rise to Good Reason setting forth the basis for Executive’s resignation, allow the Company at least 30 days from receipt of such written notice to cure such event, and if such event is not reasonably cured within such period, Executive must resign from all positions Executive then holds with the Company not later than 90 days after the expiration of the cure period.

• Change in Control. For purposes of this Agreement, “Change in Control” shall have the meaning set forth in the Lexeo Therapeutics, Inc. 2023 Equity Incentive Plan.

• Proprietary Information Obligations.

• Confidential Information Agreement. As a condition of employment, Executive shall execute and abide by the Company’s standard form of Employee Confidential Information And Inventions Assignment Agreement (the “Confidentiality Agreement”).

• Third-Party Agreements and Information. Executive represents and warrants that Executive’s employment by the Company does not conflict with any prior employment or consulting agreement or other agreement with any third party, and that Executive will perform Executive’s duties to the Company without violating any such agreement. Executive represents and warrants that Executive does not possess confidential information arising out of prior employment, consulting, or other third party relationships, that would be used in connection with Executive’s employment by the Company, except as expressly authorized by that third party. During Executive’s employment by the Company, Executive will use in the performance of Executive’s duties only information which is generally known and used by persons with training and experience comparable to Executive’s own, common knowledge in the industry, otherwise legally in the public domain, or obtained or developed by the Company or by Executive in the course of Executive’s work for the Company. Executive expressly acknowledges that she will not use any confidential or proprietary information of a third-party in connection with the performance of his duties to the Company.

• Outside Activities During Employment.

• Non-Company Business. Except with the prior written consent of the Board, Executive will not during the term of Executive’s employment with the Company undertake or engage in any other employment, occupation or business enterprise, other than ones in which Executive is a passive investor. In any event, Executive may: (i) engage in civic and not- for-profit activities; (ii) engage in activities in connection with personal investments; (iii) serve, following receiving consent from the Board (which shall not unreasonably be withheld), on board of directors positions for up to two (2) organizations, and (iv) serve as an advisor, or as a member of an advisory board, following receiving consent from the Board (which shall not unreasonably be withheld), on up to two (2) organizations; so long as such activities do not materially interfere with the performance of Executive’s duties hereunder.

• No Adverse Interests. Executive agrees not to acquire, assume or participate in, directly or indirectly, any position, investment or interest known to be adverse or antagonistic to the Company, its business or prospects, financial or otherwise. This does not prohibit the Executive from purchasing any publicly listed securities or funds which hold publicly listed securities.

• Dispute Resolution. To ensure the timely and economical resolution of disputes that may arise in connection with Executive’s employment with the Company, Executive and the Company agree that any and all disputes, claims, or causes of action arising from or relating to the enforcement, breach, performance, negotiation, execution, or interpretation of this Agreement, the Confidential Information Agreement, or Executive’s employment, or the termination of Executive’s employment, including but not limited to all statutory claims, with the exception of discrimination and harassment claims, will be resolved pursuant to the Federal Arbitration Act, 9 U.S.C. §1-16 (the “FAA”), and to the fullest extent permitted by law, by final, binding and confidential arbitration by a single arbitrator conducted in New York, New York by Judicial Arbitration and Mediation Services Inc. (“JAMS”) under the then applicable JAMS rules appropriate to the relief being sought (the applicable rules are available at the following web addresses: (i) https://www.jamsadr.com/rules-employment-arbitration/ and (ii) https://www.jamsadr.com/rules-comprehensive-arbitration/); provided, however, this arbitration provision not apply to any action or claim that cannot be subject to mandatory arbitration as a matter of law, including, without limitation, claims involving allegations of sexual harassment and discrimination, to the extent such claims are not permitted by applicable law(s) to be submitted to mandatory arbitration and the applicable law(s) are not preempted by the FAA or otherwise invalid (collectively, the “Excluded Claims”). A hard copy of the rules will be provided to Executive upon request. A hard copy of the rules will be provided to Executive upon request. By agreeing to this arbitration procedure, both Executive and the Company waive the right to resolve any such dispute through a trial by jury or judge or administrative proceeding. In addition, all claims, disputes, or causes of action under this section, whether by Executive or the Company, must be brought in an individual capacity, and shall not be brought as a plaintiff (or claimant) or class member in any purported class or representative proceeding, nor joined or consolidated with the claims of any other person or entity. The Arbitrator may not consolidate the claims of more than one person or entity, and may not preside over any form of representative or class proceeding. To the extent that the preceding sentences regarding class claims or proceedings are found to violate applicable law or are otherwise found unenforceable, any claim(s) alleged or brought on behalf of a class shall proceed in a court of law rather than by arbitration. The Company acknowledges that Executive will have the right to be represented by legal counsel at any arbitration proceeding. Questions of whether a claim is subject to arbitration under this Agreement) shall be decided by a federal court in the State of New York. However, procedural questions which grow out of the dispute and bear on the final disposition are matters for the arbitrator. The arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by law; (b) issue a written arbitration decision, to include the arbitrator’s essential findings and conclusions and a statement of the award; and (c) be authorized to award any or all remedies that Executive or the Company would be entitled to seek in a court of law. Executive and the Company shall equally share all JAMS’ arbitration fees. To the extent JAMS does not collect or Executive otherwise does not pay to JAMS an equal share of all JAMS’ arbitration fees for any reason, and the Company pays JAMS Executive’s share, Executive acknowledges and agrees that the Company shall be entitled to recover from Executive half of the JAMS arbitration fees invoiced to the parties (less any amounts Executive paid to JAMS) in a federal or state court of competent jurisdiction. Except as modified in the Confidential Information Agreement, each party is responsible for its own attorneys’ fees. Nothing in this Agreement is intended to prevent either Executive or the Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Any awards or orders in such arbitrations may be entered and enforced as judgments in the federal and state courts of any competent jurisdiction. To the extent a New York federal court determines that any applicable law prohibits mandatory arbitration of Excluded Claims, if Executive intends to bring multiple claims, including one or more Excluded Claims, the Excluded Claim(s) may be publicly filed with a court, while any other claims will remain subject to mandatory arbitration.

• Section 280G Matters.

• If any payment or benefit Executive will or may receive from the Company or otherwise (a “280G Payment”) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but for this Section, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax”), then any such 280G Payment provided pursuant to this Agreement (a “Payment”) shall be equal to the Reduced Amount. The “Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment (after reduction) being subject to the Excise Tax, or (y) the largest portion, up to and including the total, of the Payment, whichever amount (i.e., the amount determined by clause (x) or by clause (y)), after taking into account all applicable federal, state, and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in Executive’s receipt, on an after-tax basis, of the greater economic benefit notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in a Payment is required pursuant to the preceding sentence and the Reduced Amount is determined pursuant to clause (x) of the preceding sentence, the reduction shall occur in the manner (the “Reduction Method”) that results in the greatest economic benefit for Executive. If more than one method of reduction will result in the same economic benefit, the items so reduced will be reduced pro rata (the “Pro Rata Reduction Method”).

• Notwithstanding any provision of this Section 12 to the contrary, if the Reduction Method or the Pro Rata Reduction Method would result in any portion of the Payment being subject to taxes pursuant to Section 409A that would not otherwise be subject to taxes pursuant to Section 409A, then the Reduction Method and/or the Pro Rata Reduction Method, as the case may be, shall be modified so as to avoid the imposition of taxes pursuant to Section 409A as follows: (A) as a first priority, the modification shall preserve to the greatest extent possible, the greatest economic benefit for Executive as determined on an after-tax basis; (B) as a second priority, Payments that are contingent on future events (e.g., being terminated without Cause), shall be reduced (or eliminated) before Payments that are not contingent on future events; and (C) as a third priority, Payments that are “deferred compensation” within the meaning of Section 409A shall be reduced (or eliminated) before Payments that are not deferred compensation within the meaning of Section 409A.

• The Company shall appoint a nationally-recognized accounting, consulting or law firm to make the determinations required by this Section 12. The Company shall bear all expenses with respect to the determinations by such firm required to be made hereunder.

• If Executive receives a Payment for which the Reduced Amount was determined pursuant to clause (x) of and the Internal Revenue Service determines thereafter that some portion of the Payment is subject to the Excise Tax, Executive agrees to promptly return to the Company a sufficient amount of the Payment (after reduction pursuant to clause (x) of Section 12(i)) so that no portion of the remaining Payment is subject to the Excise Tax. For the avoidance of doubt, if the Reduced Amount was determined pursuant to clause (y) of Section 12(i), Executive shall have no obligation to return any portion of the Payment pursuant to the preceding sentence.

• General Provisions.

• Notices. Any notices provided must be in writing and will be deemed effective upon the earlier of personal delivery (including personal delivery by fax) or the next day after sending by overnight carrier, to the Company at its primary office location and to Executive at the address as listed on the Company payroll.

• Severability. Whenever possible, each provision of this Agreement will be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Agreement is held to be invalid, illegal or unenforceable in any respect under any applicable law or rule in any jurisdiction, such invalidity, illegality or unenforceability will not affect any other provision or any other jurisdiction, but this Agreement will be reformed, construed and enforced in such jurisdiction to the extent possible in keeping with the intent of the parties.

• Waiver. Any waiver of any breach of any provisions of this Agreement must be in writing to be effective, and it shall not thereby be deemed to have waived any preceding or succeeding breach of the same or any other provision of this Agreement.

• Complete Agreement. This Agreement, together with the Confidentiality Agreement, constitutes the entire agreement between Executive and the Company with regard to this subject matter and is the complete, final, and exclusive embodiment of the Parties’ agreement with regard to this subject matter. This Agreement is entered into without reliance on any promise or representation, written or oral, other than those expressly contained herein, and it supersedes any other such promises, warranties or representations. It is entered into without reliance on any promise or representation other than those expressly contained herein, and it cannot be modified or amended except in a writing signed by a duly authorized officer of the Company.

• Amendments and Waivers. This Agreement cannot be changed, modified or amended, and no provision or requirement hereof may be waived, without the consent in writing of the Executive and the Company. The failure of a party at any time or times to require performance of any provision hereof shall in no manner affect the right of such party at a later time to enforce the same. No waiver by a party of the breach of any term or covenant contained in this Agreement, whether by conduct or otherwise, in any one or more instances, shall be deemed to be, or construed as, a further or continuing waiver of any such breach, or a waiver of the breach of any other term or covenant in this Agreement.

• Counterparts. This Agreement may be executed in separate counterparts, any one of which need not contain signatures of more than one party, but all of which taken together will constitute one and the same Agreement.

• Headings. The headings of the paragraphs hereof are inserted for convenience only and shall not be deemed to constitute a part hereof nor to affect the meaning thereof.

• Successors and Assigns. This Agreement is intended to bind and inure to the benefit of and be enforceable by Executive and the Company, and their respective successors, assigns, heirs, executors and administrators, except that Executive may not assign any of his duties hereunder and he may not assign any of his rights hereunder without the written consent of the Company, which shall not be withheld unreasonably.

• Tax Withholding and Indemnification. All payments and awards contemplated or made pursuant to this Agreement will be subject to withholdings of applicable taxes in compliance with all relevant laws and regulations of all appropriate government authorities. Executive acknowledges and agrees that the Company has neither made any assurances nor any guarantees concerning the tax treatment of any payments or awards contemplated by or made pursuant to this Agreement. Executive has had the opportunity to retain a tax and financial advisor and fully understands the tax and economic consequences of all payments and awards made pursuant to the Agreement.

• Choice of Law. All questions concerning the construction, validity and interpretation of this Agreement will be governed by the laws of the State of New York.

In Witness Whereof, the Parties have executed this Agreement on the day and year written below.

LEXEO THERAPEUTICS, INC.
By:	/s/ R. Nolan Townsend
R. Nolan Townsend
Chief Executive Officer
Date:	8/12/2025
LOUIS TAMAYO
/s/ Louis Tamayo
Chief Financial Officer
Date:	8/12/2025

CORRECTION TO

EMPLOYMENT AGREEMENT

THIS CORRECTION TO EMPLOYMENT AGREEMENT (this “Correction”) corrects the employment agreement made between Lexeo Therapeutics, Inc. (the “Company”) and Louis Tamayo (the “Executive”) dated August 12, 2025 (the “Employment Agreement”). This Correction is effective as of the effective date of the Employment Agreement (the “Effective Date”). Capitalized terms used herein but not defined shall have the meanings given to such terms in the Employment Agreement.

WHEREAS, the Company and Executive have agreed to amend Section 5.5 of the Employment Agreement in order to correct the termination provisions in connection with change in control.

NOW, THEREFORE, in consideration of the mutual promises and covenants set forth herein, and other good and valuable consideration, receipt of which is hereby acknowledged, the parties to this Correction hereby agree that the Employment Agreement shall be amended as follows:

• Amendment to Section 5.5. As of the Effective Date, the first paragraph of Section 5.5 of the Employment Agreement is hereby amended and restated as follows:

“5.5 Termination in Connection with Change in Control. If the Company terminates

Executive’s employment without Cause, or Executive resigns for Good Reason, no more than three (3) months prior to a Change in Control (as defined herein) or within twelve (12) months after a Change in Control, Executive shall be entitled to receive the following severance benefit (in lieu of, and not in addition to, the benefits described in Section 5.3):”

• Miscellaneous.
• No Other Amendment. Except as modified by this Correction, the Employment Agreement shall remain in full force and effect in all respects without any modification.
• Subsequent Adjustments to Compensation Terms. Any adjustments to Executive’s compensation terms (including but not limited to base salary and bonus) implemented subsequent to the date of the Employment Agreement will be unaffected by the Correction and will remain in effect notwithstanding this Correction.
• At Will. Nothing in this Correction shall modify the at-will nature of the employment relationship.
• Successors and Assigns. The terms and conditions of this Correction shall inure to the benefit of and be binding upon the respective successors and assigns of the parties. Nothing in this Correction, express or implied, is intended to confer upon any party other than the parties hereto or their respective successors and assigns any rights, remedies, obligations, or liabilities under or by reason of this Correction, except as expressly provided in this Correction.
• Arbitration: Choice of Laws. This Correction shall be governed in all respects by the dispute resolution provisions of the Employment Agreement (including, without limitation, provisions regarding mandatory arbitration and governing law).
• Titles and Subtitles. The titles and subtitles used in this Correction are used for convenience only and are not to be considered in construing or interpreting this Correction.
• Counterparts. This Correction may be executed in any number of counterparts, each of which shall be enforceable against the parties that execute such counterparts, and all of which together shall constitute one instrument.

IN WITNESS WHEREOF, the parties hereto have executed this Correction as of the date set forth

above.

Lexeo Therapeutics, Inc.:		Executive:
By:
Signature:	/s/ R. Nolan Townsend	Signature:	/s/ Louis Tamayo
Name:	R. Nolan Townsend	Name:	Louis Tamayo
Title:	Chief Executive Officer

EX-10.7

Exhibit 10.7

TRANSITION AND SEPARATION AGREEMENT

This Transition and Separation Agreement (the “Agreement”) is made between Lexeo Therapeutics, Inc. (the “Company”) and Kyle Rasbach (the “Executive”) in connection with Executive’s separation from the Company.

• Separation Date; Transition Period.
• Executive’s last day of employment with the Company will be August 29, 2025, provided, however, Executive’s employment may be earlier terminated: (i) by the mutual written agreement of the parties hereto; (ii) by the Company in accordance with Paragraph 1(b) below; or (iii) by Executive’s voluntary resignation from employment with the Company (such last day of employment, as applicable, shall be referred to herein as (the “Separation Date”). Regardless of whether Executive signs this Agreement, Executive will be paid at Executive’s current rate of pay, through the Separation Date (the “Accrued Compensation”).
• The period from the date hereof to and including the Separation Date, shall be referred to as the “Transition Period”. During the Transition Period, Executive will be expected to continue performing the ordinary duties and responsibilities of Executive’s role and to assist in the transition of Executive’s duties and responsibilities as the Company may deem necessary and appropriate. For the avoidance of doubt, during the Transition Period, Executive shall continue to be employed exclusively by the Company and may not be employed by or provide services in any capacity to any other person, business or other third-party.
• For the avoidance of doubt, the Company may terminate Executive’s employment for “Cause” during the Transition Period under the same conditions for which the Company can otherwise terminate the Executive for Cause under the employment agreement between Executive and the Company dated December 13, 2024.
• As of the Separation Date, Executive will cease holding any position or title with the Company, and Executive will no longer be eligible or entitled to receive any compensation other than as expressly set forth herein.
• Consideration. In consideration of the releases and covenants given by Executive as set forth in this Agreement, including but not limited to the Release (as such term is defined below), and Executive’s compliance therewith, and provided that Executive executes, and do not revoke, this Agreement in accordance with the timeframes set forth herein, the Company agrees as follows:

During the Transition Period, (i) Executive will be paid at Executive’s regular annual base salary rate as of the date hereof, less all applicable federal, state and local withholding taxes and deductions, payable in accordance with the Company’s normal payroll practices (the “Base Salary Payments”), and (ii) Executive will continue to be covered by Executive’s employee benefits, subject to the requirements, conditions and limitations of such benefits, which may be amended from time to time. The payments contemplated in this Paragraph 2(a) will be reported on an IRS Form W-2.

• In addition, provided that Executive executes, and does not revoke, this Agreement in accordance with the timeframes set forth herein and Executive is not terminated by the Company for Cause at any time, the Company will, on the Separation Date:

• Pay Executive an amount approximately equal to a pro rated bonus for calendar 2025 in the gross amount of One Hundred and Twenty-Eight Thousand Dollars ($128,000), less all applicable federal, state and local withholding taxes and authorized deductions. The Payment will be paid in a lump sum, and will be reported on an IRS Form W-2.

• Accelerate two-thirds (66.67%) of one-quarter (25%) of Executive’s currently outstanding unvested Lexeo stock options (the “Options”), equivalent to 40,466 options. The exercise of the Options will remain subject to the terms of the Lexeo Therapeutics, Inc. 2023 Equity Incentive Plan.

• The Company will not contest any lawful application Executive makes for unemployment compensation benefits; provided, however, that the Company will respond truthfully to all mandatory inquiries directed to it by a governmental agency. It is understood that the Company does not make unemployment compensation benefits eligibility decisions and that the payments and benefits described in this Paragraph may affect Executive’s eligibility for unemployment compensation benefits.

• Compensation or Benefits. Executive acknowledges that, except as expressly provided in this Agreement, Executive has not earned and will not receive from the Company any additional compensation (including base salary, bonus, incentive compensation, or equity), severance, or benefits before or after the Separation Date, with the exception of any vested right Executive may have under the express terms of a written ERISA-qualified benefit plan (e.g., 401(k) account) or any vested stock options, and that the payments described in Paragraph 2 above are in lieu of and in full satisfaction of any amounts that might otherwise be payable under any contract, plan, policy, or practice of the Company.

• Expense Reimbursements. Executive agrees that, within thirty (30) days after the Separation Date, Executive will submit Executive’s final documented expense reimbursement statement reflecting all business expenses Executive incurred through the Separation Date, if any, for which Executive seeks reimbursement. The Company will reimburse Executive for these expenses in accordance with its regular business practice.

• Return of Company Property. Executive agrees that, by the Separation Date, Executive will return to the Company all Company documents (and all copies thereof) and other Company property in Executive’s possession or control, including, but not limited to, Company files, notes, drawings, records, plans, forecasts, reports, studies, analyses, proposals, agreements, drafts, financial and operational information, research and development information, sales and marketing information, customer lists, prospect information, pipeline reports, sales reports, personnel information, specifications, code, software, databases, computer-recorded information, tangible property and equipment (including, but not limited to, computing and electronic devices, mobile telephones, servers), credit cards, entry cards, identification badges and keys; and any materials of any kind which contain or embody any proprietary or confidential information of the Company (and all reproductions or embodiments thereof in whole or in part). Executive agrees that Executive will make a diligent search to locate any such documents, property and information by the close of business on the Separation Date or as soon as possible thereafter. If Executive has used any personally-owned computer or other electronic device, server, or e-mail system to receive, store, review, prepare or transmit any Company confidential or proprietary data, materials or information, by the Separation Date, Executive shall provide the Company with a computer-useable copy of such information and then permanently delete and expunge such Company confidential or proprietary information from those systems; and Executive agree to provide the Company access to Executive’s system as requested to verify that the necessary copying and/or deletion is completed. Executive’s timely compliance with this paragraph is a condition to Executive’s receipt of the severance benefits set forth in Paragraph 2(b) above.

• Proprietary Information Obligations. Executive acknowledges and reaffirms Executive’s continuing obligations under Executive’s Confidential Information and Inventions Assignment Agreement, a copy of which is attached hereto as Exhibit A.

• Confidentiality. The provisions of this Agreement will be held in strictest confidence by Executive and will not be publicized or disclosed by Executive in any manner whatsoever; provided, however, that: (a) Executive may disclose this Agreement in confidence to Executive’s immediate family and to Executive’s attorneys, accountants, tax preparers and financial advisors; and (b) Executive may disclose this Agreement insofar as such disclosure may be necessary to enforce its terms or as otherwise required by law. In particular, and without limitation, Executive agree not to disclose the terms of this Agreement to any current or former Company employee or independent contractor.

• Trading in Lexeo Securities. In light of Executive’s exposure to confidential and sensitive information of the Company, including information that could be viewed as material non-public information, Executive agrees that he shall not himself or through others engage in trading in Lexeo securities for a period of six (6) months following his Separation Date.

• Non-disparagement. Executive agrees not to disparage the Company, its officers, directors, employees, shareholders, parents, subsidiaries, affiliates, and agents, in any manner likely to be harmful to its or their business, business reputation, or personal reputation; provided that Executive may respond accurately and fully to any request for information if required by legal process or in connection with a government investigation. In addition, the Company agrees that its officers and directors will not disparage Executive in any manner likely to be harmful to Executive’s business, business reputation, or personal reputation; provided that the Company may respond accurately and fully to any request for information if required by legal process or in connection with a government investigation.

Nothing in this provision or this Agreement is intended to prohibit or restrain Executive in any manner from making disclosures protected under the whistleblower provisions of federal or state law or regulation or other applicable law or regulation. Executive agrees to revise and update publicly available information, including professional and social networking websites such as LinkedIn and Facebook, within one (1) week of the Separation Date to remove any indication that Executive is employed by the Company.

• References. In response to any reference request from a prospective employer, the Company will only confirm Executive’s dates of employment and position.

• No Voluntary Adverse Action. Executive agrees that Executive will not voluntarily (except in response to legal compulsion or as permitted under the Protected Rights section below) assist any person in bringing or pursuing any proposed or pending litigation, arbitration, administrative claim or other formal proceeding against the Company, its parent or subsidiary entities, affiliates, officers, directors, employees or agents.

• Cooperation. Executive agrees to cooperate fully with the Company in connection with its actual or contemplated defense, prosecution, or investigation of any claims or demands by or against third parties, or other matters arising from events, acts, or failures to act that occurred during the period of Executive’s employment by the Company. Such cooperation includes, without limitation, making Executive available to the Company upon reasonable notice, without subpoena, to provide complete, truthful and accurate information in witness interviews, depositions, and trial testimony. The Company will reimburse Executive for reasonable out-of-pocket expenses Executive incurs in connection with any such cooperation (excluding foregone wages and attorneys’ fees) and will make reasonable efforts to accommodate Executive’s scheduling needs.

• No Admissions. Executive understands and agree that the promises and payments in consideration of this Agreement shall not be construed to be an admission of any liability or obligation by the Company to Executive or to any other person, and that the Company makes no such admission.

• Release of Claims. In exchange for the consideration provided to Executive under this Agreement to which Executive would not otherwise be entitled, Executive hereby generally and completely release the Company, and its affiliated, related, parent and subsidiary entities, and its and their current and former directors, officers, employees, shareholders, partners, agents, attorneys, predecessors, successors, insurers, affiliates, and assigns from any and all claims, liabilities, demands, causes of action, and obligations, both known and unknown, arising from or in any way related to events, acts, conduct, or omissions occurring at any time prior to and including the date Executive sign this Agreement. This general release includes, but is not limited to: (a) all claims arising from or in any way related to Executive’s employment with the Company or the termination of that employment; (b) all claims related to Executive’s compensation or benefits from the Company, including salary, bonuses, commissions, vacation pay, expense reimbursements, severance pay, fringe benefits, stock, stock options, or any other ownership, equity, or profits interests in the Company; (c) all claims for breach of contract, wrongful termination, and breach of the implied covenant of good faith and fair dealing; (d) all tort claims, including claims for fraud, defamation, emotional distress, and discharge in violation of public policy; and (e) all federal, state, and local statutory claims, including claims for discrimination, harassment, retaliation, attorneys’ fees, or other claims arising under the federal Civil Rights Act of 1964 (as amended), the federal Americans with Disabilities Act of 1990, the Age Discrimination in Employment Act (“ADEA”), the New York State Human Rights Law, the New York Labor Law, the New York Wage Theft Prevention Act, Section 125 of the New York Workers’ Compensation Law, the New York City Human Rights Law, the New York City Administrative Code, the Massachusetts Fair Employment Practices Act, the Massachusetts Equal Pay Act, the Massachusetts Civil Rights Act, the Massachusetts Labor and Industries Act, the Massachusetts Right to Privacy law, and the Massachusetts Wage Act, all as amended, and any other federal, state or local statutes, regulations, ordinances prohibiting discrimination or regulating employment or the payment of wages. Notwithstanding the foregoing, Executive is not releasing the Company hereby from: (i) any obligation to indemnify Executive pursuant to the Articles and Bylaws of the Company, any valid fully executed indemnification agreement with the Company, applicable law, or applicable directors and officers liability insurance; (ii) any claims that cannot be waived by law; or (iii) any claims for breach of this Agreement.

• ADEA Release. Executive acknowledges that Executive is knowingly and voluntarily waiving and releasing any rights Executive have under the ADEA, and that the consideration given for the waiver and releases Executive have given in this Agreement is in addition to anything of value to which Executive were already entitled. Executive further acknowledge that Executive have been advised, as required by the ADEA, that: (a) Executive’s waiver and release does not apply to any rights or claims arising after the date Executive signs this Agreement; (b) Executive should consult with an attorney prior to signing this Agreement (although Executive may choose voluntarily not to do so); (c) Executive has twenty-one (21) days to consider this Agreement (although Executive may choose voluntarily to sign it sooner); (d) Executive has seven (7) days following the date Executive signs this Agreement to revoke this Agreement (in a written revocation sent to the Company, specifically to Jennifer Speer via email at jcspeer@lexeotx.com); and (e) this Agreement will not be effective until the date upon which the revocation period has expired, which will be the eighth day after Executive sign this Agreement provided that Executive does not revoke it (the “Effective Date”).

• Protected Rights. Executive understands that nothing in this Agreement limits Executive’s ability to file a charge or complaint with the Equal Employment Opportunity Commission, the Department of Labor, the National Labor Relations Board, the Occupational Safety and Health Administration, the New York State Department of Labor, the Securities and Exchange Commission or any other federal, state or local governmental agency or commission (“Government Agencies”). Executive further understands this Agreement does not limit Executive’s ability to communicate with any Government Agencies or otherwise participate in any investigation or proceeding that may be conducted by any Government Agency, including providing documents or other information, without notice to the Company. While this Agreement does not limit Executive’s right to receive an award for information provided to the Securities and Exchange Commission, Executive understands and agrees that, to maximum extent permitted by law, Executive are otherwise waiving any and all rights Executive may have to individual relief based on any claims that Executive has released and any rights Executive have waived by signing this Agreement.

• Breach; Attorneys’ Fees. Executive acknowledges and agrees that any material breach of this Agreement, unless such breach constitutes a legal action by Executive challenging or seeking a determination in good faith of the validity of the waiver herein under the ADEA, or its exhibits (if any) shall entitle the Company immediately to recover and/or cease providing the consideration provided to Executive under this Agreement and to obtain damages, except as provided by law, provided, however, that the Company shall not recover Fifty Dollars ($50.00) of the consideration already paid pursuant to this Agreement and such amount shall serve as full and complete consideration for the promises and obligations assumed by Executive under this Agreement and its exhibits. In addition, except with regard to a legal action challenging or seeking a determination in good faith of the validity of the waiver herein under the ADEA, in the event that either party brings an action to enforce or effect its rights under this Agreement, the prevailing party shall be entitled to recover its costs and expenses, including the costs of mediation, arbitration, litigation, court fees, and reasonable attorneys’ fees incurred in connection with such an action.

• Representations. Executive hereby represents that Executive has: been paid all compensation owed and for all hours worked; received all leave and leave benefits and protections for which Executive is eligible pursuant to the Family and Medical Leave Act, the New York Paid Family Leave Law, the Massachusetts Parental Leave Law, or otherwise; and has not suffered any on-the-job injury for which Executive has not already filed a workers’ compensation claim.

• Dispute Resolution. Executive and the Company agree that any and all disputes, claims, or controversies of any nature whatsoever arising from, or relating to, this Agreement or its interpretation, enforcement, breach, performance or execution, Executive’s employment or the termination of such employment (including, but not limited to, any statutory claims) (collectively, “Claims”, each a “Claim”), shall be resolved, pursuant to the Federal Arbitration Act, 9 U.S.C. §1-16, and to the fullest extent permitted by law, by final, binding and confidential arbitration in New York, New York (or another mutually acceptable location) conducted before a single neutral arbitrator by JAMS, Inc. (“JAMS”) or its successor, under the then applicable JAMS Arbitration Rules and Procedures for Employment Disputes (available at http://www.jamsadr.com/rules-employment-arbitration/). By agreeing to this arbitration procedure, both Executive and the Company waive the right to have any Claim resolved through a trial by jury or judge or an administrative proceeding. Executive will have the right to be represented by legal counsel at any arbitration proceeding, at Executive’s own expense. This paragraph shall not apply to any action or claim that cannot be subject to mandatory arbitration as a matter of law. The arbitrator shall have sole authority for determining if a Claim is subject to arbitration, and any other procedural questions related to the dispute and bearing on the final disposition. In addition, the arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be available under applicable law in a court proceeding; and (b) issue a written statement signed by the arbitrator regarding the disposition of each claim and the relief, if any, awarded as to each claim, the reasons for the award, and the arbitrator’s essential findings and conclusions on which the award is based. Executive and the Company shall equally share all JAMS’ arbitration fees. To the extent JAMS does not collect or Executive otherwise do not pay to JAMS an equal share of all JAMS’ arbitration fees for any reason, and the Company pays JAMS Executive’s share, Executive acknowledge and agree that the Company shall be entitled to recover from Executive half of the JAMS arbitration fees invoiced to the parties (less any amounts Executive paid to JAMS) in a federal or state court of competent jurisdiction. Nothing in this letter agreement is intended to prevent either Executive or the Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Any awards or orders in such arbitrations may be entered and enforced as judgments in the federal and state courts of any competent jurisdiction.

• Complete Agreement. This Agreement, including Exhibit A, constitutes the complete, final and exclusive embodiment of the entire agreement between Executive and the Company with regard to its subject matter. Executive agrees and acknowledges that this Agreement is entered into without reliance on any promise or representation, written or oral, other than those expressly contained herein, and it supersedes any other such promises, warranties or representations.

• Miscellaneous.

• This Agreement may not be modified or amended except in a writing signed by both Executive and a duly authorized officer of the Company.

• This Agreement will bind the heirs, personal representatives, successors and assigns of both Executive and the Company, and inure to the benefit of both Executive and the Company, their heirs, successors and assigns.

• If any provision of this Agreement is determined to be invalid or unenforceable, in whole or in part, this determination will not affect the validity or enforceability of any other provision of this Agreement and the provision in question will be modified by the court so as to be rendered enforceable to the fullest extent permitted by law, consistent with the intent of the parties. Moreover, if one or more of the provisions contained in this Agreement shall be held to be excessively broad as to duration, scope, activity or subject, such provisions shall be construed by limiting or reducing them so as to be enforceable to the maximum extent compatible with applicable law.

• This Agreement will be deemed to have been entered into and will be construed and enforced in accordance with the laws of the State of New York without regard to conflict of laws principles.

• Any ambiguity in this Agreement shall not be construed against either party as the drafter. Any waiver of any condition or breach of this Agreement shall be in writing and shall not be deemed to be a waiver of any other condition or breach, nor shall the failure of or delay by either of the parties in exercising any right, power, or privilege hereunder operate as a waiver thereof to preclude any other or further exercise thereof or the exercise of any other such right, power, or privilege.

• This Agreement may be executed in counterparts and electronic or facsimile signatures will suffice as original signatures.

Executive has twenty-one (21) calendar days to decide whether to accept this Agreement, and the

Agreement’s terms will expire if Executive does not sign and return it within that timeframe.

The Parties have executed this Agreement on the day and year written below.

LEXEO THERAPEUTICS, INC.		KYLE RASBACH
By:	/s/ R. Nolan Townsend	/s/ Kyle Rasbach
R. Nolan Townsend		Chief Financial Officer
Chief Executive Officer
Date:	8/13/2025	Date:	08/13/2025

EXHIBIT A

CONFIDENTIAL INFORMATION

AND INVENTIONS ASSIGNMENT AGREEMENT

[See Next Page]

EX-10.8

Exhibit 10.8

[***] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL.

Center for Technology Licensing

1155 York Avenue New York, NY 10065 P: 646.962.7045

innovation.weill.cornell.edu

Weill Cornell Medicine Enterprise Innovation

October 30, 2024

[***]

RE: FOURTH AMENDMENT

to the FIRST LICENSE AGREEMENT by and between Lexeo Therapeutics, Inc. (hereinafter “Licensee”) and Cornell University (“Cornell”) (each a “Party”) effective May 28, 2020, and amended a first time effective July 4, 2022, a second time effective September 28, 2022, and a third time effective Feb 16, 2024 (Cornell Contract [***]) (the “First License Agreement”)

Effective the date of the last signature hereto (“Amendment Date”), the Parties agree to hereby modify the First License Agreement as follows:

• Appendix A: Inventions of the First License Agreement is hereby amended to include:

[***]

• Appendix B1: Patent Rights of the First License Agreement is hereby amended to include:

[***]

• The lists of dockets on the cover page and in the Notices section of the First License Agreement shall include [***].
• Paragraph 1.9 is hereby changed from:

1.9 “Field” means all human and non-human prophylactic and therapeutic uses of Licensed Products.

to:

1.9 “Field” means all human and non-human prophylactic and therapeutic uses of Licensed Products, other than Licensed Products that would be a Licensed Product if (i) [***] were included in Patent Rights or (ii) [***] were included in Technology.

• As consideration for this Amendment, Licensee will pay Cornell an amendment fee of [***] within [***] of the Amendment Date.

• These changes do not otherwise change the terms and conditions of the First License Agreement.

• This Amendment may be executed by electronic signatures or by facsimile and in two (2) or more counterparts, each of which shall be deemed an original and all of which together shall constitute but one and the same instrument.

IN WITNESS WHEREOF, both Cornell and Licensee have executed this Amendment by their respective and duly authorized officers on the day and year written.

CORNELL UNIVERSITY		LEXEO THERAPEUTICS, INC.
By:	/s/ Lisa Placanica	By:	/s/ Frank Borchetta
	[Signature of Authorized Officer]		[Signature of Authorized Officer]
Name:	Lisa Placanica	Name:	Frank Borchetta
Title:	Senior Managing Director	Title:	Senior Director, IP Counsel
Date:	3/5/2025	Date:	3/5/2025

EX-10.9

Exhibit 10.9

[***] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL.

Appendix D: Amendment to Second License Agreement

April 21, 2024

[***]

RE: 3rd AMENDMENT

to the SECOND LICENSE AGREEMENT by and between the Parties effective May 28, 2020, amended a first time effective January 13, 2022 and a second time effective July 4, 2022 (Cornell Contract [***]) (the “Second License Agreement”)

Effective the date of the last signature hereto (“Amendment Date”), the Parties agree to hereby modify the Second License Agreement as follows:

• On the cover page and in Paragraph 10.1, “D-9332” is hereby deleted.

• The following row is deleted from Appendix A: Inventions:

[***]

• Paragraph 1.27 “Net Sales” is hereby amended as follows in order to remove references to “Portfolio FA Supp”:

• In the first paragraph, the following parenthetical is hereby deleted:

“(other than a Licensed Product developed using the Technology included in Portfolio FA Supp and no other Patent Rights, Nonexclusive Patent Rights or other Technology included herein)”

• The following paragraph is hereby deleted:

The Parties agree, that for purposes of calculating royalties due hereunder, Net Sales shall not include any sales of Licensed Products that are developed based on Portfolio FA Supp and no other Patent Rights, Nonexclusive Patent Rights or other Technology.

• Paragraph 1.35 “Portfolio” is hereby deleted and replaced with the following, in order to remove reference to “Portfolio FA Supp”:

1.35 “Portfolio” means each of the groupings of Inventions, Patent Rights, Nonexclusive Patent Rights, Technology and Licensed Methods identified in the Cornell docket or dockets defined in Paragraphs 3.3(a)(iii)-(v) as Portfolio Batten or Portfolio ARSA (each as defined below).

• Paragraph 3.1(c)(ii), copied below, is hereby deleted and replaced with “This subsection left purposefully blank”, in order to remove reference to “Portfolio FA Supp”:

(ii) With respect to Portfolio FA Supp, for each service, composition or product supported by Portfolio FA Supp:

AMOUNT	DATE OR EVENT
[***]	[***]
[***]	[***]

• Paragraph 3.3(a)(v), copied below, is hereby deleted and replaced with “This subsection left purposefully blank”, in order to remove reference to “Portfolio FA Supp”:

• develop a Licensed Product for a central nervous system disease based on Cornell Docket D-9332 (“Portfolio FA Supp”) as follows, wherein each row in the following table is an obligation under this Paragraph 3.3(a)(vii):

MILESTONE TO BE ACHIEVED	TIME FROM EFFECTIVE DATE BY WHICH MILESTONE MUST BE ACHIEVED
[***]	[***]
[***]	[***]
[***]	[***]

• Paragraph 3.3(a)(vi) is hereby deleted and replaced with the following, in order to remove references to “Portfolio FA Supp”:

• incur Research Expenditures for each of Portfolio Batten and Portfolio ARSA as follows:

PORTFOLIO DESCRIPTION	RESEARCH EXPENDITURE MILESTONE TO BE ACHIEVED DURING EACH CONSECUTIVE TWO CLENDAR YEAR PERIOD (COMMENCING ON JANUARY 1, 2021)
[***]	[***]

• Paragraph 3.3(b) is hereby deleted and replaced with the following, in order to remove references to “Portfolio FA Supp”:

(b) Subject to Paragraph 3.3(c), if LICENSEE or its applicable Sublicensee fails to perform any of its obligations specified in Paragraphs 3.3(a)(i)-(ix), then Cornell as its sole remedy shall have the right and option to terminate this Agreement as follows:

(i) in the case of Paragraph 3.3(a)(ii), Cornell shall have the right to terminate this Agreement in full in accordance with the terms and conditions of this Agreement, and

(ii) in the case Paragraphs 3.3(a)(i) and (iii)-(ix), solely with respect to the Licensed Product for the applicable Portfolio Batten or Portfolio ARSA, Cornell shall have the right to terminate this Agreement in part (but not as a whole) with respect to specific dockets or under the Patent Rights or under the Nonexclusive Patent Rights with respect to such applicable Portfolio Batten or Portfolio ARSA.

• These changes do not otherwise change the terms and conditions of the Second License Agreement.
• This Amendment may be executed by electronic signatures or by facsimile and in two (2) or more counterparts, each of which shall be deemed an original and all of which together shall constitute but one and the same instrument.

IN WITNESS WHEREOF, both Cornell and Licensee have executed this Amendment by their respective and duly authorized officers on the day and year written.

-- Signatures on following page --

CORNELL UNIVERSITY		LEXEO THERAPEUTICS, INC.
By:	/s/ Lisa Placanica	By:	/s/ R. Nolan Townsend
			[Signature of Authorized Officer]
Name:	Lisa Placanica	Name:	R. Nolan Townsend
Title:	Senior Managing Director	Title:	Chief Executive Officer
Date:	4/21/2024	Date:	4/21/2024

EX-10.10

Exhibit 10.10

[***] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL.

FIRST AMENDMENT TO THE LICENSE AGREEMENT BETWEEN

LEXEO THERAPEUTICS, INC.

AND

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

This First Amendment (“Amendment”) by and between Lexeo Therapeutics, Inc. located at 345 Park Avenue South, Sixth Floor, New York, NY 10010 (“LICENSEE”) and The Regents of the University of California a California public corporation having its statewide administrative offices at 1111 Franklin Street, Oakland, California 94607-5200 (“UNIVERSITY”), represented by its San Diego campus having an address at University of California San Diego, Office of Innovation and Commercialization, Mail Code 0910, 9500 Gilman Drive, La Jolla, California 92093-0910 (“UC SAN DIEGO”) is made and effective as of the last date of signature (“Effective Date”).

WHEREAS, LICENSEE and UNIVERSITY entered into a License Agreement, effective on October 4, 2021 (“License Agreement”, UC Agreement Control No. [***]), that exclusively licensed UNIVERSITY’s rights to the patent application entitled “Gene Therapy for Arrhythmogenic Right Ventricular Cardiomyopathy” (“Patent Rights”), UCSD Case No. [***], and related written nonpublic technical information to LICENSEE.

WHEREAS, LICENSEE and UNIVERSITY mutually desire to amend the Agreement pursuant to Section 10.10 as set forth below;

NOW THEREFORE, in consideration of the premises and mutual covenants herein, the parties agree as follows:

• Paragraph 1.23 shall be deleted and replaced with: “Technology” means the written nonpublic technical information, if any, relating to the Invention which the Inventors provided to LICENSEE prior to the Effective Date and which is detailed in Exhibit C. For clarity, technology also includes any information or other intellectual property embodied in the Invention, including information that was confidential at any time before the Effective Date.

• Article 5 shall be renamed “Intellectual Property Matters”.

• Paragraph 5.2 shall be renamed “Intellectual Property Litigation”.

• Paragraph 5.2(b) shall be added and shall state: To the extent permitted by law, LICENSEE shall have the right to initiate suit to correct inventorship of patent(s) assigned to third parties relating to the subject matter of the Invention to include as a named inventor an Inventor (“Inventorship Claims”). If UNIVERSITY (based on actual knowledge of the licensing professional responsible for administering this Invention) or LICENSEE learns of potential Inventorship Claims, the knowledgeable party promptly will inform the other party of the potential Inventorship Claim and provide evidence relevant to the potential Inventorship Claim available to the knowledgeable party (“Inventorship Claim Notice”). UNIVERSITY and LICENSEE agree to discuss and determine how best to proceed. [***] after the Inventorship Claim Notice, or earlier by agreement of UNIVERSITY and LICENSEE or to comply with an applicable statutory or equitable deadline to file, LICENSEE may inform UNIVERSITY of its intention to initiate suit, and LICENSEE shall initiate suit as soon as practicable thereafter, subject to the additional requirements set forth in this section. If LICENSEE has not declared its intention to initiate suit within [***] of the Inventorship Claim Notice, then UNIVERSITY may initiate suit. Any such patent(s) or patent application(s) for which inventorship is corrected in connection with an Inventorship Claim shall be automatically included within the scope of Patent Rights, as defined in Section 1.18.

• Paragraph 5.2(c) shall be added and shall state: To the extent permitted by law, LICENSEE shall have the right to file suit to protect its exclusive license to use Technology in the Field within the Territory, and during the Term, including the right to file suit based on misuse of information or other intellectual property within the scope of the Technology, and other related claims (“Information Claims”). If UNIVERSITY (based on actual knowledge of the licensing professional responsible for administering this Invention) or LICENSEE learns of potential Information Claims, the knowledgeable party promptly will inform the other party of the potential Information Claim and provide evidence relevant to the potential Information Claim available to the knowledgeable party (“Information Claim Notice”). UNIVERSITY and LICENSEE agree to discuss and determine how best to proceed. [***] after the Information Claim Notice, or earlier by agreement of UNIVERSITY and LICENSEE or to comply with an applicable statutory or equitable deadline to file, LICENSEE may inform UNIVERSITY of its intention to initiate suit, and LICENSEE shall initiate suit as soon as practicable thereafter, subject to the additional requirements set forth in this section. If LICENSEE has not initiated suit within [***] of the Information Claim Notice, then UNIVERSITY may initiate suit. Any information or other intellectual property that is assigned or licensed to UNIVERSITY in connection with an Information Claim shall be automatically included within the scope of Technology, as defined in Paragraph 1.23.

• The final paragraph in Paragraph 5.2 shall be deleted and replaced with: Notwithstanding the foregoing: (1) UNIVERSITY may not be joined in any suit without its prior written consent; (2) LICENSEE may not admit liability or wrongdoing on behalf of UNIVERSITY without its prior written consent; (3) Each party will cooperate with the other in litigation initiated under Paragraph 5.2, but at the expense of the party who initiated the suit; (4) If UNIVERSITY is joined in any suit under Paragraph 5.2, LICENSEE will pay all of UNIVERSITY’s costs; (5) If UNIVERSITY is a party to a suit under Paragraph 5.2, then the recovery to UNIVERSITY will be greater than or equal to [***] of net recoveries; (6) Any agreement made by LICENSEE for purposes of settling litigation or other dispute regarding Patent Rights, Inventorship Claims, or Information Claims will comply with the requirements of Paragraph 2.2 (Sublicense); and (7) If LICENSEE or UNIVERSITY (but not both) sues a third party for infringement of Patent Rights, Inventorship Claims, or Information Claims, then the non-suing party may not thereafter sue such infringer for the acts of infringement raised in the suit.

• Capitalized terms used herein that are not otherwise defined shall have the same meanings ascribed to such terms in the Agreement.

• If the terms of the Agreement in any way conflict with or are otherwise inconsistent with the terms of this Amendment, the terms of this Amendment shall govern and control.

• Except as modified herein, the above-referenced Agreement, and the subsequent Amendments shall remain in full force and effect and is hereby incorporated by reference. The Agreement, as amended and modified, constitutes the entire agreement and understanding between the parties.

• This Amendment may be executed in two or more counterparts, each of which shall be deemed an original, but all of which shall constitute one and the same instrument.

IN WITNESS WHEREOF, the parties have caused this Amendment to be executed by their duly authorized representatives as of the Effective Date.

THE REGENTS OF THE UNIVERSITY<br><br>OF CALIFORNIA		LEXEO THERAPEUTICS, INC.
By:	/s/ Victoria Cajipe, Ph.D.
Victoria Cajipe, Ph.D.		By:	/s/ Jenny Robertson
Associate Director, Innovation &		Print Name:	Jenny Robertson
Commercialization		Title:	Chief Business & Legal Officer
Date:	8/7/2024	Date:	8/8/2024

EX-10.11

Exhibit 10.11

[***] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL.

AMENDMENT No. 2

TO THE LICENSE AGREEMENT UC CONTROL No. [***]

BETWEEN LEXEO THERAPEUTICS AND

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Lexeo Therapeutics and the Regents of the University of California (“UNIVERSITY”) represented by its San Diego campus (“UC SAN DIEGO”) entered into a License Agreement, UC SAN DIEGO Control Number [***] (“Agreement”) effective October 4, 2021 and amended (Amendment No.1) effective August 8, 2024. The parties now wish to amend such Agreement, to be effective upon the date of last signature of this Amendment No.2 (“Amendment Effective Date”) to include certain modifications. These modifications are to be substituted for the relevant sections and/or paragraphs in the Agreement, and are effective from the Amendment Effective Date.

For these purposes, the parties agree on the following changes as detailed below.

ARTICLE 5. PATENT MATTERS.

Delete Paragraph 5.1 in its entirety and replace it with the following:

“

• LICENSEE shall be responsible for the prosecution and maintenance of any Patent Rights claiming or covering any Inventions, and UNIVERSITY shall reasonably cooperate with LICENSEE in connection with the same, including, upon the request of LICENSEE, promptly executing any and all patent applications, formal documents, assignments, or other instruments which LICENSEE deems necessary or reasonably useful for the filing, prosecution, and maintenance, of any Patent Rights claiming or covering any such Inventions, which may be filed or prepared at LICENSEE's cost and expense.
• LICENSEE shall keep UNIVERSITY reasonably informed of the prosecution of Patent Rights. LICENSEE shall provide UNIVERSITY with a copy of material communications from any patent authority regarding such Inventions, and shall provide drafts of any material filings or responses to be made to such patent authorities a reasonable amount of time in advance of submitting such filings or responses so that UNIVERSITY may have an opportunity to review and comment.
• If LICENSEE plans to abandon, cease prosecution or not maintain any patent(s) or patent application(s) in Patent Rights, then to avoid abandonment or other loss of rights, LICENSEE will provide UNIVERSITY with at least [***] notice of such plan and UNIVERSITY shall have the right, in UNIVERSITY's sole discretion, to file for or continue prosecution and/or maintenance of such patent or patent application at its own expense.
• For clarity, nothing in this Amendment relieves LICENSEE from its obligation to make disclosures to UNIVERSITY.”

In consideration for this Amendment No. 2, LICENSEE shall pay UNIVERSITY an amendment fee of [***] within [***] of receipt of an invoice.

All other terms and conditions in the Agreement between LICENSEE and UNIVERSITY effective October 4, 2021 shall remain unchanged and in effect.

The parties agree this Amendment No. 2 may be executed electronically and in two or more counterparts each of which shall be deemed an original and all of which together shall constitute but one and the same document.

IN WITNESS WHEREOF, both UNIVERSITY and LICENSEE have executed this Agreement by their respective and duly authorized officers on the day and year written.

LEXEO THERAPEUTICS, INC.:		THE REGENTS OF THE<br><br>UNIVERSITY OF CALIFORNIA:
By:	/s/ Jenny Robertson	By:	/s/ Anthony Reza Razavi, Ph.D.
	(Signature)		(Signature)
Jenny Robertson		Anthony Reza Razavi, Ph.D.
Chief Business & Legal Officer		Associate Director - Innovation and<br><br>Commercialization
Date:	5/28/2025	Date:	2025-05-16

EX-10.12

Exhibit 10.12

[***] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL.

AMENDMENT No. 1

TO THE LICENSE AGREEMENT UC CONTROL No. [***]

BETWEEN LEXEO THERAPEUTICS AND

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

UC case [***]

Lexeo Therapeutics, Inc. (“LICENSEE,” a successor in interest to Stelios Therapeutics, Inc.) and the Regents of the University of California (“UNIVERSITY”) represented by its San Diego campus (“UC SAN DIEGO”) wish to amend the License Agreement between the parties, UC SAN DIEGO Control Number [***] (UC case [***]), effective August 6, 2020 (“Agreement”), to include certain modifications. This Amendment No. 1 to the Agreement shall be effective upon the date of last signature (“Amendment Effective Date”). These modifications are to be substituted for the relevant sections and/or paragraphs in the Agreement and are effective from the Amendment Effective Date.

WHEREAS, UNIVERSITY and Stelios Therapeutics, Inc. entered into the Agreement on August 6, 2020.

WHEREAS, LICENSEE acquired Stelios Therapeutics, Inc. on July 16, 2021, and LICENSEE became the successor in interest to Stelios Therapeutics, Inc. under the Agreement.

For the purposes described above, the parties agree on the following changes as detailed below.

ARTICLE 5. PATENT MATTERS.

Delete Paragraph 5.1 in its entirety and replace it with the following:

“

• LICENSEE shall be responsible for the prosecution and maintenance of any Patent Rights claiming or covering any Inventions, and UNIVERSITY shall reasonably cooperate with LICENSEE in connection with the same, including, upon the request of LICENSEE, promptly executing any and all patent applications, formal documents, assignments, or other instruments which LICENSEE deems necessary or reasonably useful for the filing, prosecution, and maintenance, of any Patent Rights claiming or covering any such Inventions, which may be filed or prepared at LICENSEE's cost and expense.
• LICENSEE shall keep UNIVERSITY reasonably informed of the prosecution of Patent Rights. LICENSEE shall provide UNIVERSITY with a copy of material communications from any patent authority regarding such Inventions, and shall provide drafts of any material filings or responses to be made to such patent authorities a reasonable amount of time in advance of submitting such filings or responses so that UNIVERSITY may have an opportunity to review and comment.
• If LICENSEE plans to abandon, cease prosecution or not maintain any patent(s) or patent application(s) in Patent Rights, then to avoid abandonment or other loss of rights, LICENSEE will provide UNIVERSITY with at least [***] notice of such plan and UNIVERSITY shall have the right, in UNIVERSITY's sole discretion, to file for or continue prosecution and/or maintenance of such patent or patent application at its own expense.
• For clarity, nothing in this Amendment relieves LICENSEE from its obligation to make disclosures to UNIVERSITY.”

In consideration for this Amendment No. 1, LICENSEE shall pay UNIVERSITY an amendment fee of [***] within [***] of receipt of an invoice.

All other terms and conditions in the Agreement between LICENSEE and UNIVERSITY effective April 23, 2020 shall remain unchanged and in effect.

The parties agree this Amendment No. 1 may be executed electronically and in two or more counterparts each of which shall be deemed an original and all of which together shall constitute but one and the same document.

IN WITNESS WHEREOF, both UNIVERSITY and LICENSEE have executed this Agreement by their respective and duly authorized officers on the day and year written.

LEXEO THERAPEUTICS, INC.:		THE REGENTS OF THE<br><br>UNIVERSITY OF CALIFORNIA:
By:	/s/ Jenny Robertson	By:	/s/ Anthony Reza Razavi, Ph.D.
	(Signature)		(Signature)
Jenny Robertson		Anthony Reza Razavi, Ph.D.
Chief Legal Officer		Associate Director - Innovation and<br><br>Commercialization
Date:	2025-06-04	Date:	2025-06-04

EX-10.13

Exhibit 10.13

[***] = CERTAIN CONFIDENTIAL INFORMATION CONTAINED IN THIS DOCUMENT, MARKED BY BRACKETS, HAS BEEN OMITTED BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL.

AMENDMENT No. 1

TO THE LICENSE AGREEMENT UC CONTROL No. [***]

BETWEEN LEXEO THERAPEUTICS AND

THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Lexeo Therapeutics, Inc. (“LICENSEE,” a successor in interest to ARVC Therapeutics, Inc. and Stelios Therapeutics, Inc.) and the Regents of the University of California (“UNIVERSITY”) represented by its San Diego campus (“UC SAN DIEGO”) wish to amend the License Agreement between the parties, UC SAN DIEGO Control Number [***], effective April 23, 2020 (“Agreement”), to include certain modifications. This Amendment No. 1 to the Agreement shall be effective upon the date of last signature (“Amendment Effective Date”). These modifications are to be substituted for the relevant sections and/or paragraphs in the Agreement and are effective from the Amendment Effective Date.

WHEREAS, UNIVERSITY and ARVC Therapeutics, Inc. entered into the Agreement April 23, 2020.

WHEREAS, ARVC Therapeutics, Inc. merged with Stelios Therapeutics, Inc. on May 19, 2020, and Stelios Therapeutics, Inc. became the successor in interest to ARVC Therapeutics, Inc. under the Agreement.

WHEREAS, LICENSEE acquired Stelios Therapeutics, Inc. on July 16, 2021, and LICENSEE became the successor in interest to Stelios Therapeutics, Inc. under the Agreement.

For the purposes described above, the parties agree on the following changes as detailed below.

ARTICLE 5. PATENT MATTERS.

Delete Paragraph 5.1 in its entirety and replace it with the following:

“

• LICENSEE shall be responsible for the prosecution and maintenance of any Patent Rights claiming or covering any Inventions, and UNIVERSITY shall reasonably cooperate with LICENSEE in connection with the same, including, upon the request of LICENSEE, promptly executing any and all patent applications, formal documents, assignments, or other instruments which LICENSEE deems necessary or reasonably useful for the filing, prosecution, and maintenance, of any Patent Rights claiming or covering any such Inventions, which may be filed or prepared at LICENSEE's cost and expense.
• LICENSEE shall keep UNIVERSITY reasonably informed of the prosecution of Patent Rights. LICENSEE shall provide UNIVERSITY with a copy of material communications from any patent authority regarding such Inventions, and shall provide drafts of any material filings or responses to be made to such patent authorities a reasonable amount of time in advance of submitting such filings or responses so that UNIVERSITY may have an opportunity to review and comment.
• If LICENSEE plans to abandon, cease prosecution or not maintain any patent(s) or patent application(s) in Patent Rights, then to avoid abandonment or other loss of rights, LICENSEE will provide UNIVERSITY with at least [***] notice of such plan and UNIVERSITY shall have the right, in UNIVERSITY's sole discretion, to file for or continue prosecution and/or maintenance of such patent or patent application at its own expense.
• For clarity, nothing in this Amendment relieves LICENSEE from its obligation to make disclosures to UNIVERSITY.”

In consideration for this Amendment No. 1, LICENSEE shall pay UNIVERSITY an amendment fee of [***] within [***] of receipt of an invoice.

All other terms and conditions in the Agreement between LICENSEE and UNIVERSITY effective April 23, 2020 shall remain unchanged and in effect.

The parties agree this Amendment No. 1 may be executed electronically and in two or more counterparts each of which shall be deemed an original and all of which together shall constitute but one and the same document.

IN WITNESS WHEREOF, both UNIVERSITY and LICENSEE have executed this Agreement by their respective and duly authorized officers on the day and year written.

LEXEO THERAPEUTICS, INC.:		THE REGENTS OF THE<br><br>UNIVERSITY OF CALIFORNIA:
By:	/s/ Jenny Robertson	By:	/s/ Anthony Reza Razavi, Ph.D.
	(Signature)		(Signature)
Jenny Robertson		Anthony Reza Razavi, Ph.D.
Chief Legal Officer		Associate Director - Innovation and<br><br>Commercialization
Date:	2025-05-30	Date:	2025-05-27

EX-31.1

Exhibit 31.1

CERTIFICATION

I, R. Nolan Townsend certify that:

• I have reviewed this Form 10-Q of Lexeo Therapeutics, Inc.;
• Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;
• Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;
• The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:
• Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;
• Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;
• Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and
• Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and
• The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):
• All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and
• Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Dated: November 5, 2025
/s/ R. Nolan Townsend
By: R. Nolan Townsend
Chief Executive Officer<br><br>(Principal Executive Officer)

EX-31.2

Exhibit 31.2

CERTIFICATION

I, Louis Tamayo certify that:

• I have reviewed this Form 10-Q of Lexeo Therapeutics, Inc.;
• Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;
• Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;
• The registrant's other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:
• Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;
• Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;
• Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and
• Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and
• The registrant's other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):
• All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and
• Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Dated: November 5, 2025
/s/ Louis Tamayo
By: Louis Tamayo
Chief Financial Officer
(Principal Financial and Accounting Officer)

EX-32.1

Exhibit 32.1

CERTIFICATION

Pursuant to the requirement set forth in Rule 13a-14(b) of the Securities Exchange Act of 1934, as amended, (the “Exchange Act”) and Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. §1350), R. Nolan Townsend, Chief Executive Officer and Principal Executive Officer of Lexeo Therapeutics, Inc. (the “Company”), hereby certifies that, to the best of his knowledge:

• The Company’s Quarterly Report on Form 10-Q for the period ended September 30, 2025, to which this Certification is attached as Exhibit 32.1 (the “Periodic Report”), fully complies with the requirements of Section 13(a) or Section 15(d) of the Exchange Act; and
• The information contained in the Periodic Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: November 5, 2025
/s/ R. Nolan Townsend
R. Nolan Townsend
Chief Executive Officer
(Principal Executive Officer)

*This certification accompanies the Form 10-Q to which it relates, is not deemed filed with the Securities and Exchange Commission and is not to be incorporated by reference into any filing of Lexeo Therapeutics, Inc. under the Securities Act of 1933, as amended, or the Exchange Act (whether made before or after the date of the Form 10-Q), irrespective of any general incorporation language contained in such filing.

EX-32.2

Exhibit 32.2

CERTIFICATION

Pursuant to the requirement set forth in Rule 13a-14(b) of the Securities Exchange Act of 1934, as amended, (the “Exchange Act”) and Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. §1350), Louis Tamayo, Chief Financial Officer and Principal Financial and Accounting Officer of Lexeo Therapeutics, Inc. (the “Company”), hereby certifies that, to the best of his knowledge:

• The Company’s Quarterly Report on Form 10-Q for the period ended September 30, 2025, to which this Certification is attached as Exhibit 32.1 (the “Periodic Report”), fully complies with the requirements of Section 13(a) or Section 15(d) of the Exchange Act; and
• The information contained in the Periodic Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

Dated: November 5, 2025
/s/ Louis Tamayo
Louis Tamayo
Chief Financial Officer
(Principal Financial and Accounting Officer)

*This certification accompanies the Form 10-Q to which it relates, is not deemed filed with the Securities and Exchange Commission and is not to be incorporated by reference into any filing of Lexeo Therapeutics, Inc. under the Securities Act of 1933, as amended, or the Exchange Act (whether made before or after the date of the Form 10-Q), irrespective of any general incorporation language contained in such filing.