8-K

UNITED STATESSECURITIES AND EXCHANGE COMMISSIONWASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): October 16, 2025

DIANTHUS THERAPEUTICS, INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware	001-38541	81-0724163
(State or Other Jurisdiction<br>of Incorporation)	(Commission File Number)	(IRS Employer<br>Identification No.)
7 Times Square<br><br>43rd Floor
New York, New York		10036
(Address of Principal Executive Offices)		(Zip Code)
Registrant’s Telephone Number, Including Area Code: (929) 999-4055
---

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

Title of each class	Trading<br>Symbol(s)	Name of each exchange on which registered
Common Stock, $0.001 Par Value	DNTH	The Nasdaq Capital Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

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. ☐

Item 1.01 Entry into a Material Definitive Agreement

License Agreement with Nanjing Leads Biolabs Co. Ltd.

On October 16, 2025, Dianthus Therapeutics, Inc. (“Dianthus” or the “Company”) entered into a License and Collaboration Agreement (the “License Agreement”) with Nanjing Leads Biolabs Co. Ltd. (“Leads”), pursuant to which Leads granted the Company a royalty-bearing, exclusive license outside of Greater China to develop, manufacture, commercialize or otherwise exploit LBL-047, referred to as DNTH212 by the Company. Dianthus also obtained certain non-exclusive rights to perform development and manufacturing activities in Greater China to support DNTH212 outside of Greater China. DNTH212 is an investigational, extended half-life bifunctional fusion protein targeting plasmacytoid dendritic cell (pDC) BDCA2 to reduce Type 1 interferon production, while simultaneously inhibiting BAFF/APRIL to suppress B cell function.

Consideration

Under the terms of the License Agreement, the Company will pay Leads up to $38 million, comprised of $30 million in upfront and near-term milestone payments plus an additional $8 million milestone, payable in cash or the Company's common stock at the Company's election, upon the initiation of a Dianthus-led Phase 1 study, for exclusive rights to develop and commercialize DNTH212 globally outside of Greater China. Leads will also be eligible to receive up to $962 million in development and regulatory approval milestones and sales-based milestones across five indications, as well as tiered royalties from mid-single digits up to a low double-digit on ex-Greater China net sales.

Governance and Development

A joint steering committee will oversee manufacturing, development, and commercial activities related to DNTH212. Leads will have the right to participate in the Company's global clinical studies with DNTH212 and enroll patients in Greater China. Leads will be responsible for certain costs with respect to patients enrolled in Greater China in the Company's global studies in which Leads has elected to participate.

Non-Competition

Leads and the Company are prohibited from directly or indirectly researching, developing, manufacturing or commercializing a competing product, as defined in the License Agreement, in the Company's territory outside of Greater China.

Term and Termination

The License Agreement will remain in effect on a country-by-country and product-by-product basis until expiration of the applicable royalty term, unless earlier terminated. Each party has customary termination rights, including for uncured material breach, insolvency, patent challenge, or, in the case of the Company, for convenience.

The foregoing description of the License Agreement does not purport to be complete and is qualified in its entirety by reference to the License Agreement, a copy of which the Company will file as an exhibit to its Annual Report on Form 10-K for the year ending December 31, 2025.

Item 2.02 Results of Operations and Financial Condition

The information set forth below under “Preliminary Financial Information for the Three Months Ended September 30, 2025” in Item 8.01 is incorporated by reference herein.

Such information is being “furnished” and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liability of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”). Such information shall not be incorporated by reference into any registration statement or other document pursuant to the Securities Act or into any filing or other document pursuant to the Exchange Act, except as otherwise expressly stated in any such filing.

Item 8.01 Regulation FD Disclosure

On October 16, 2025, the Company made publicly available on the investor relations section of its website a presentation announcing the execution of the License Agreement in connection with a conference call with investors to be held at 8:00 a.m. ET on October 16, 2025 (the “Presentation”). The Presentation is filed as Exhibit 99.1 and is incorporated by reference into this Item 8.01.

Preliminary Financial Information for the Three Months Ended September 30, 2025

In the Presentation, the Company disclosed its estimated cash, cash equivalents and investments as of September 30, 2025. While the Company has not finalized its full financial results for the three months ended September 30, 2025, the Company expects to report that it had approximately $555 million of cash, cash equivalents and investments as of September 30, 2025, with pro forma cash of approximately $525 million of cash, cash equivalents, and investments after deducting near term and upfront milestone payments to Leads of $30 million. This amount is preliminary, has not been audited and is subject to change pending completion of the Company’s unaudited financial statements for the three months ended September 30, 2025. Additional information and disclosures would be required for a more complete understanding of the Company’s financial position and results of operations as of September 30, 2025. The Company’s independent registered public accounting firm has not audited, reviewed or performed any procedures with respect to this preliminary information and, accordingly, does not express an opinion or any other form of assurance about such information.

Forward-Looking Statements

This Current Report on Form 8-K contains statements that may constitute “forward-looking statements” within the meaning of the federal securities laws, including, but not limited to, statements relating to the Company’s expected financial results and the License Agreement. Words such as “may,” “might,” “will,” “objective,” “intend,” “should,” “could,” “can,” “would,” “expect,” “believe,” “design,” “estimate,” “predict,” “potential,” “anticipate,” “goal,” “opportunity,” “develop,” “plan” or the negative of these terms, and similar expressions, or statements regarding intent, belief, or current expectations, are forward looking statements. While the Company believes these forward-looking statements are reasonable, undue reliance should not be placed on any such forward-looking statements, which are based on information available to us on the date of this report. These forward-looking statements are based upon current estimates and assumptions and are subject to various risks and uncertainties (including, without limitation, those set forth in the Company's filings with the SEC), many of which are beyond the Company's control and subject to change. Actual results could be materially different. The Company claims the protection of the Safe Harbor contained in the Private Securities Litigation Reform Act of 1995 for forward-looking statements and expressly disclaims any obligation to update or alter any statements whether as a result of new information, future events or otherwise, except as required by law.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit No.	Description
99.1	Company Presentation, dated October 16, 2025
104	Cover Page Interactive Data File (embedded within the inline XBRL document)

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 hereunto duly authorized.

			DIANTHUS THERAPEUTICS, INC.
Date:	October 16, 2025	By:	/s/ Adam M. Veness, Esq.
			Adam M. Veness, Esq.<br>SVP, General Counsel and Secretary

Dianthus TherapeuticsLicensing of DNTH212 (BDCA2 and BAFF/APRIL) from Leads Biolabs October 16, 2025 Exhibit 99.1

Forward-looking statements Certain statements in this presentation, other than purely historical information, may constitute “forward-looking statements” within the meaning of the federal securities laws, including for purposes of the safe harbor provisions under the United States Private Securities Litigation Reform Act of 1995, express or implied statements regarding future plans and prospects, including statements regarding the expectations or plans for discovery, preclinical studies, clinical trials and research and development programs, in particular with respect to claseprubart and DNTH212, and any developments or results in connection therewith, including the target product profile and administration of claseprubart and DNTH212; the anticipated timing of the initiation and results from those studies and trials; expectations regarding the clinical trial designs or indications; expectations regarding the time period over which the Company’s capital resources are expected to be sufficient to fund its anticipated operations; and expectations regarding market size, patient population size, and potential opportunities for complement therapies, in particular with respect to claseprubart and DNTH212. Claseprubart and DNTH212 are investigational agents that are not approved as therapies in any indication in any jurisdiction worldwide. The words “opportunity,” “potential,” “milestones,” “runway,” “will,” “anticipate,” “achieve,” “near-term,” “catalysts,” “pursue,” “pipeline,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “possible,” “predict,” “project,” “should,” “strive,” “would,” “aim,” “target,” “commit,” and similar expressions (including the negatives of these terms or variations of them) generally identify forward-looking statements, but the absence of these words does not mean that statement is not forward looking. Actual results could differ materially from those included in the forward-looking statements due to various factors, risks and uncertainties, including, but not limited to, that preclinical testing of claseprubart and DNTH212 and data from clinical trials may not be predictive of the results or success of ongoing or later clinical trials, that the development of claseprubart or DNTH212 may take longer and/or cost more than planned, that the Company or its partner may be unable to successfully complete the clinical development of the Company’s compounds, that the Company or its partner may be delayed in initiating, enrolling or completing its planned clinical trials, and that the Company's compounds may not receive regulatory approval or become commercially successful products. These and other risks and uncertainties are identified under the heading "Risk Factors" included in the Company’s Annual Report on Form 10-K for the period ended December 31, 2024, and other filings that the Company has made and may make with the SEC in the future. Nothing in this presentation should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. Nothing in this Presentation should be regarded as a representation by any person that the forward-looking statements set forth herein will be achieved or that any of the contemplated results of such forward-looking statements will be achieved. Dianthus undertakes no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law.

Introduction Marino Garcia, Chief Executive Officer DNTH212 Opportunity Overview Simrat Randhawa, MD, Head of Research & Development Deal Terms & Strategic Perspectives Ryan Savitz, Chief Financial Officer & Chief Business Officer Marino Garcia, Chief Executive Officer Q&A Marino Garcia, Chief Executive Officer Simrat Randhawa, MD, Head of Research & Development Ryan Savitz, Chief Financial Officer & Chief Business Officer Agenda

DNTH212 (BDCA2 and BAFF/APRIL inhibitor) expands leadership in next-generation therapeutics Entered into an exclusive license agreement with Leads Biolabs for global rights (ex-Greater China1) for DNTH212, a first and potentially best-in-class, Ph. 1 ready bifunctional BDCA2 and BAFF/APRIL inhibitor IND cleared by FDA with Ph. 1 SAD study in healthy volunteers and patients with SLE expected to initiate in Q4’25 in China with top-line HV results expected in 2H’26 Pro forma estimated cash of ~$525M2 maintains runway into 2028, expected to fund multiple catalysts Builds on favorable safety and clinical PoC for BDCA2 and BAFF/APRIL targeted biologics, with potential for enhanced efficacy from complementary mechanisms targeting innate and adaptive immune systems Continues Dianthus’ strategy of pursuing clinically validated MoAs with next-generation best-in-class therapeutics and a pipeline-in-a-product potential DNTH212 demonstrated superior in vitro inhibition of pDCs vs. litifilimab and superior Ig reductions in NHPs vs. povetacicept highlighting potential for improved clinical benefit in severe autoimmune diseases Note: DNTH212 is being developed in China by Leads Biolabs as LBL-047 1. Greater China includes Mainland China, Hong Kong, Macau, and Taiwan Targeting patient-friendly convenience with S.C. self-administration and Q4W or less frequent dosing 2. Estimated pro forma cash includes preliminary and unaudited cash, cash equivalents and investments as of September 30, 2025 of approximately $555 million less $30 million of upfront and near-term milestone payments

DNTH212 Opportunity Overview

Inhibiting BDCA2 reduces Type 1 interferon production from plasmacytoid dendritic cells (pDCs) Single CRD2 domain of TACI designed to deliver robust B cell modulation via BAFF/APRIL inhibition DNTH212 targets both the innate and adaptive immune systems with complementary disease modifying mechanisms enabling potential best-in-class efficacy DNTH212 is a bifunctional BDCA2 and BAFF/APRIL inhibitor targeting two well-validated pathways Anti-BDCA2 Antibody Potent inhibition of Type 1 interferon TACI-CRD2 Domain Potent reduction of Ig levels via BAFF/APRIL inhibition Afucosylated Bifunctional Ab Enhanced ADCC on target cells leads to pDC depletion YTE Mutation on Fc Extended half-life DNTH212 Humanized monoclonal antibody targeting BDCA2 fused with TACI-CRD2

Potential to drive superior clinical efficacy by targeting both the innate and adaptive immune systems Panda SK, et al., Plasmacytoid dendritic cells in autoimmunity. Curr Opin Immunol. 2017 Feb;44:20-25. Minaga K, et al., Plasmacytoid Dendritic Cells as a New Therapeutic Target for Autoimmune. Front Immunol. 2021 Jul 23;12:713779 Bifunctional approach addressing autoimmune diseases where both Type 1 interferon and B Cells are implicated has strong mechanistic rationale for potential best-in-class efficacy Adaptive Immune System: B Cells Generate autoantibodies, forming immune complexes that trigger inflammation and tissue damage Inhibiting BAFF/APRIL has been shown effective in multiple autoimmune diseases Innate Immune System: Plasmacytoid Dendritic Cells (pDCs) Key cell type producing Type I IFN Promote B cell proliferation and Ig secretion through antigen presentation and production of BAFF Direct and indirect activation of other innate and adaptive immune cells Type 1 interferon inhibition has been shown effective in multiple autoimmune diseases DNTH212 Systemic inflammation DNTH212 Systemic inflammation Expression BDCA2 ITAM pathway pDC Type 1 IFNs BAFF TACI IgM APRIL IgG IgA B cell NK cells TLR7/9 Autoantigen Plasma cell Type 1 IFNs Autoantibody immune complexes

DNTH212 achieves superior pDC depletion compared to litifilimab in vitro Comparable Suppression of Pro-Inflammatory Cytokine IFN-α1 Deeper Depletion of pDC2 Method: Human PBMCs from a healthy donor were co-cultured with a TLR9 agonist and serially diluted antibodies for 24 hours. IFN-α release in the supernatant was measured using an HTRF kit Method: Human PBMCs from a healthy donor were co-cultured with serially diluted antibodies for 24 hours. pDC counts were assessed via flow cytometry pDC depletion removes a key cell type involved in Type I IFN production and activation of other immune cells which contribute to disease

DNTH212 shows superior inhibition of IgM, IgA, and IgM compared to povetacicept following single dose in NHPs S.C. DNTH212 IV povetacicept and telitacicept1 Note: These data are derived from different studies at different points in time, with differences in methodology, design and populations. As a result, cross-trial comparisons cannot be made, and no head-to-head clinical trials of DNTH212 and other agents have been conducted Arthritis Rheumatol.2023 Jul;75(7):1187-1202. Note: WT TACI (13-118) Fc:Telitacicept IgM IgA IgG Deeper Ig reductions have potential to drive superior clinical efficacy while maintaining at least Q4W dosing Maximal Ig Inhibition DNTH212 10mg/kg Povetacicept1 9mg/kg IgM 76% ~60% IgA 66% ~50% IgG 38% ~30% Telitacicept (9mg/kg IV) Vehicle Control Povetacicept (9mg/kg IV) Nadir ~27 days ~60% ~50% ~30% IgM IgA IgG DNTH212 (1mg/kg S.C.) DNTH212 (10mg/kg S.C.) Nadir ~43 days

Validation of both BDCA2 and BAFF/APRIL targeted therapies support DNTH212 bifunctional approach Note: Company press releases and investor presentations Positive Litifilimab (BDCA2) Data in SLE / CLE BAFF/APRIL Validation Across Multiple Autoimmune Indications and Strategic Activity

Biological Rationale Clinical Evidence Primary Sjögren's Syndrome ~350,000 U.S. Patients  B Cell: ianalumab positive Ph. 3; telitacicept positive Ph. 3 Cutaneous Lupus Erythematosus ~300,000 U.S. Patients  Type 1 interferon: litifilimab positive Ph. 2 Systemic Lupus Erythematosus ~225,000 U.S. Patients  Type 1 interferon: anifrolumab approved; litifilimab positive Ph. 2 B Cell: belimumab approved; telitacicept approved (CN); ianalumab positive Ph. 2 Lupus Nephritis ~120,000 U.S. Patients  B Cell: belimumab approved Dermatomyositis ~50,000 U.S. Patients  Type 1 interferon: dazukibart positive Ph. 2 Broad opportunity for DNTH212 across multiple diseases where Type 1 Interferon and B Cells are implicated Type 1 interferon targeting Ph. 3 studies currently ongoing in: SLE, CLE, LN, Scleroderma, DM. B Cell (BAFF/APRIL) targeting Ph. 3 studies currently ongoing in: LN, SLE Estimated U.S. patients per Dianthus meta-analysis and estimates Indications with biological rationale Indications with biological rationale and supportive clinical data Biological Rationale Hidradenitis Suppurativa ~330,000 U.S. Patients  Scleroderma ~75,000 U.S. Patients  Pemphigus Vulgaris ~32,000 U.S. Patients  Dianthus to provide update on indication prioritization in 2026

Expect to start Ph. 1 study in China in Q4’25 with top-line Part A HV results in 2H’26 5mg N = 2:0 S.C. Administration Healthy Volunteers (Part A) ~46 HVs enrolled into seven cohorts: Treated (N= up to 6) Placebo (N= up to 2) ~30 patients enrolled into three cohorts: Treated (N= up to 10) Healthy Volunteers (Part A) SLE Patients (Part B) Safety, PK, and PD as well as other biomarkers and preliminary efficacy Key Parameters US IND cleared in September 2025, IND in China expected to clear Q4 2025 S.C. Administration SLE Patients (Part B) 20mg N = 3:1 60mg N = 6:2 180mg N = 6:2 360mg N = 6:2 720mg N = 6:2 1080mg N = 6:2 Dose 1 N = 10 Dose 2 N = 10 Dose 3 N = 10 As of September 2025, subject to China IND clearance.

DNTH212 TPP aims to deliver superior efficacy in a safe and well-tolerated therapy with patient friendly convenience Achieving the TPP would position DNTH212 as a first-line biologic across a range of indications Bifunctional approach has potential for superior efficacy in various disease states versus only targeting innate or adaptive immune system SAFETY EFFICACY CONVENIENCE Inhibiting Type 1 interferon or BAFF/APRIL has been generally safe and well-tolerated Targeting patient friendly S.C. self-administration with Q4W or less frequent dosing

DNTH212 Expands Leadership in Next-generation Therapeutics for Severe Autoimmune Diseases

Favorable upfront and near-term economics with no impact on previously guided cash runway into 2028 Up to $38M comprised of $30M in upfront and near-term milestone payments plus an additional $8M milestone upon the initiation of a Dianthus-led Phase 1 study Future Milestone Payments Upfront and Near-Term Payments Royalties on Net Sales Leads Biolabs will be eligible to receive future payments up to $962M in development and regulatory approval milestones and sales-based milestones across multiple indications Leads Biolabs will be eligible to receive tiered royalties from mid-single digits up to a low double digit on ex-Greater China1 net sales Pro forma estimated cash of ~$525M2 maintains runway into 2028, including the planned development of DNTH212 Greater China includes Mainland China, Hong Kong, Macau, and Taiwan Estimated pro forma cash includes preliminary and unaudited cash, cash equivalents and investments as of September 30, 2025 of approximately $555 million less $30 million of upfront and near-term milestone payments

DNTH212 expands our leadership in next-generation therapeutics with best-in-class potential Value Proposition Claseprubart DNTH212 Validated Mechanism of Action(s) aC1s: gMG, CIDP Classical Pathway: gMG, CIDP, MMN BDCA2: SLE, CLE BAFF/APRIL: SLE, Sjögren’s, IgAN, MG, RA Best-in-class Potential Superior affinity, potency, and convenience vs. riliprubart Superior convenience and potential potency and safety advantage vs. empasiprubart Dual mechanism, targeting innate and adaptive immune systems Superior in-vitro pDC depletion vs. litifilimab Superior serum Ig inhibition vs. povetacicept in NHPs Convenient Dosing & Administration Targeting self-administered S.C. Q2W or Q4W Targeting self-administered S.C. Q4W or less frequent dosing Pipeline-in-a-product gMG, CIDP, MMN Announce prioritized indications in 2026 DNTH212 illustrates our strategy of pursuing next-generation therapeutics with clinically validated MoAs and best-in-class potential

Achieving DNTH212 TPP would position DNTH212 as a first-line, best-in-class therapy across multiple indications Type 1 interferon and BAFF/APRIL are known drivers of autoimmune disease Potential S.C. self-administration Q4W or less frequent Targeting innate and adaptive immune systems has potential for superior efficacy Inhibiting Type 1 interferon or BAFF/APRIL has been generally safe and well-tolerated Broad opportunity across multiple diseases where Type 1 interferon and B-cells are implicated Composition of matter patent expected to expire no earlier than 2044 Patient-friendly Convenience Superior Efficacy Clinically Validated MoA Favorable Safety Potential Pipeline-in-a-Product Robust IP Protection DNTH212 is an investigational agent that is not approved as a therapy in any indication in any jurisdiction worldwide

DNTH212 bolsters pipeline and builds on our vision of being a leader in severe autoimmune diseases gMG: >100,000 gMG U.S. patients from Komodo claims data accessed 2013-2025; approx. 85% of gMG patients have AChR autoantibody-driven disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7033452/# CIDP & MMN: Komodo claims data 2013-2025, adjusted to account for 70% capture of real-world patient counts for biologic treated patients; CIDP adjusted to account for 27% misdiagnosed Two clinical stage next-generation therapies with potential to address significant unmet needs across a range of severe autoimmune diseases with multiple near-term catalysts Program Indication Ph. 1 Ph. 2 Ph. 3 Upcoming Milestones Claseprubart aC1s gMG >100,000 U.S. Patients Expect to initiate Ph. 3 study in 2026 CIDP >40,000 U.S. Patients Interim responder analysis expected in 2H’26 Peer Catalyst: Riliprubart Ph. 3 MOBILIZE and VITALIZE (H2H vs IVIG) data expected in 2H’26 MMN >10,000 U.S. Patients Ph. 2 top-line results expected in 2H’26 Peer Catalyst: Empasiprubart Ph. 3 data in 2H’26 DNTH212 BDCA2 and BAFF/APRIL Multiple Autoimmune Diseases Ph. 1 HV top-line results expected in 2H’26 Announce prioritized indications in 2026 Healthy volunteers (Part A) SLE patients (Part B)

October 16, 2025 Q&ALicensing of DNTH212 (BDCA2 and BAFF/APRIL) from Leads Biolabs