8-K - SMMT - Equibles

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, 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): May 1, 2025

Summit Therapeutics Inc.
(Exact Name of Registrant as Specified in Its Charter)
Delaware	001-36866	37-1979717
(State or Other Jurisdiction<br>of Incorporation)	(Commission<br>File Number)	(IRS Employer<br>Identification No.)
601 Brickell Key Drive, Suite 1000, Miami, FL		33131
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s Telephone Number, Including Area Code: (305) 203-2034

Not applicable
(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 (see General Instruction A.2. below):

☐ 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 Symbol(s)	Name of Each Exchange on Which Registered
Common stock, $0.01 par value per share	SMMT	The Nasdaq Stock Market LLC

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 2.02	Results of Operations and Financial Condition.

On May 1, 2025, Summit Therapeutics Inc. (the “Company”) issued a press release announcing its financial results and operational progress for the first quarter ended March 31, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated by reference into this Item 2.02 as if fully set forth herein.

In accordance with General Instruction B.2 of Form 8-K, the information set forth under Item 2.02 and in Exhibit 99.1 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 liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

Item 7.01	Regulation FD Disclosure.

The Company will utilize slides during its earnings call scheduled for 4:30pm ET on May 1, 2025 to announce its first quarter 2025 financial results and provide an operational update for the Company. A copy of the slides is furnished as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated by reference into this Item 7.01 as if fully set forth herein.

In accordance with General Instruction B.2 of Form 8-K, the information set forth under Items 2.02 and 7.01 and in Exhibits 99.1 and 99.2 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 of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such filing.

Item 9.01	Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number	Description
99.1	Press Release, dated May 1, 2025
99.2	Presentation Slides for May 1, 2025 Earnings Call
104	Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURE

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.

	SUMMIT THERAPEUTICS INC.
Date: May 1, 2025	By:	/s/ Manmeet S. Soni
		Chief Operating Officer, Chief Financial Officer and Director
		(Principal Financial Officer)

a2025_prx0501xq12025earn

1 Summit Therapeutics Reports Financial Results and Operational Progress for the First Quarter Ended March 31, 2025 Ivonescimab in Combination with Chemotherapy Achieves Statistically Significant Superiority in PFS vs. Tislelizumab (PD-1 Inhibitor) Plus Chemotherapy in First-Line Treatment of Patients with Advanced Squamous NSCLC in HARMONi-6 Study Conducted by Akeso in China Enrollment Continues in Global Phase III Trial HARMONi-3 in First-Line Treatment of Patients with Metastatic NSCLC Ivonescimab Receives Approval in China as Monotherapy for First-Line Treatment for Advanced NSCLC in Tumors with Positive PD-L1 Expression: Interim Overall Survival HR = 0.777 in China for HARMONi-2 Study Conducted by Akeso Enrollment Has Begun in HARMONi-7 Global Phase III Trial in First-Line PD-L1 High, Metastatic NSCLC Ivonescimab Collaborations Progressing in Multiple Solid Tumor Settings: MD Anderson Collaboration Begins Enrolling Two Clinical Trials; Additional ISTs Initiated and Enrolling Leadership Team Advanced with Appointment of Robert LaCaze as Chief Commercial Officer Miami, Florida, May 1, 2025 - Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today reports its financial results and provides an update on its operational progress for the first quarter ended March 31, 2025. Operational & Corporate Updates Operational progress continues with ivonescimab (SMT112), an investigational, potentially first-in-class bispecific antibody combining the effects of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects associated with blocking VEGF into a single molecule: • In January 2023, we closed our Collaboration and License Agreement with Akeso Inc. (Akeso, HKEX Code: 9926.HK) for ivonescimab (SMT112), with which over 2,300 patients have been treated in clinical studies globally. Summit has rights to develop and commercialize ivonescimab in the United States, Canada, Europe, Japan, Latin America, including Mexico and all countries in Central America, South America, and the Caribbean, the Middle East, and Africa while Akeso retains development and commercialization rights for the rest of the world, including China. • Since in-licensing ivonescimab, we have begun our development for ivonescimab in non-small cell lung cancer (“NSCLC”), specifically launching Phase III clinical trials in the following proposed indications: ◦ HARMONi: Ivonescimab combined with chemotherapy in patients with epidermal growth factor receptor (EGFR)-mutated, locally advanced or metastatic non-squamous NSCLC who have progressed after treatment with a third-generation EGFR tyrosine kinase inhibitor (TKI)

2 ◦ HARMONi-3: Ivonescimab combined with chemotherapy in first-line metastatic NSCLC patients ◦ HARMONi-7: Ivonescimab monotherapy in first-line metastatic NSCLC patients with high PD-L1 expression • In October 2024, we completed enrollment in our HARMONi clinical trial. We expect to disclose topline results from HARMONi in mid-2025. Enrollment continues in HARMONi-3 and the initial patients have been enrolled in the US in HARMONi-7. • On April 23, 2025, our partner, Akeso, announced that the HARMONi-6 Phase III clinical trial met its primary endpoint of progression-free survival (PFS) at a prespecified interim analysis conducted by an Independent Data Monitoring Committee. This trial evaluated ivonescimab combined with platinum- based chemotherapy against tislelizumab, a PD-1 inhibitor, with the same chemotherapy regimen in patients with locally advanced or metastatic squamous NSCLC, regardless of PD-L1 expression. Conducted in China by our partners at Akeso, the trial showed statistically significant and clinically meaningful improvement in PFS for ivonescimab plus chemotherapy. Akeso noted that no new safety signals were identified. o This study is the first known Phase III trial in NSCLC to show significant improvement over a PD- (L)1 inhibitor combined with chemotherapy in a head-to-head setting. Following the success of Akeso’s HARMONi-2 study, this is the second instance where ivonescimab-based regimens have demonstrated a significant PFS benefit in front-line treatment in NSCLC. The full data set for HARMONi-6 is planned to be presented at an upcoming major medical conference later this year. • On April 25, 2025, Akeso announced that ivonescimab was approved in China by the National Medical Products Administration (NMPA), the Chinese Health Authority, for a second indication based on the results of the HARMONi-2 trial. HARMONi-2 evaluated monotherapy ivonescimab against monotherapy pembrolizumab in patients with locally advanced or metastatic NSCLC whose tumors have positive PD- L1 expression. HARMONi-2 is a single region, multi-center, Phase III study conducted in China sponsored by Akeso with all relevant data exclusively generated, managed, and analyzed by Akeso. o As a part of the review of the supplemental marketing application submitted by Akeso seeking a label expansion of ivonescimab in China, the NMPA requested that Akeso perform an interim analysis of overall survival (OS). Akeso announced that the results of this interim overall survival analysis included a clinically meaningful, strongly positive trend represented by a hazard ratio of 0.777. The analysis was conducted at 39% data maturity, with a nominal alpha level of 0.0001. • Ivonescimab clinical trial collaborations with leading organizations continue to progress and expand evaluating ivonescimab in solid tumor settings outside of metastatic non-small cell lung cancer. o As part of our strategic collaboration with MD Anderson, two clinical trials sponsored by MD Anderson began enrolling this past quarter in cutaneous squamous cell carcinoma and glioblastoma. o We continue to support investigator-sponsored trials (ISTs) beyond our work with MD Anderson; two ISTs have begun enrolling at the Memorial Sloan Kettering Cancer Center and the Dana Farber Cancer Institute.

3 o As we announced in February, our clinical trial collaboration with Pfizer will evaluate multiple antibody drug conjugates (ADCs) in combination with ivonescimab in unique solid tumor settings. The studies combining ivonescimab with Pfizer’s vedotin ADCs are planned to begin later this year. We plan to review the data generated from these clinical trials as a part of our consideration for advancing our clinical development for ivonescimab beyond non-small cell lung cancer. • In March, we further strengthened our leadership team with the appointment of Robert LaCaze as Chief Commercial Officer. Prior to joining Summit, Mr. LaCaze has held senior positions at major pharmaceutical companies including Executive Vice President and Head of the Oncology Strategic Business Unit overseeing the global oncology franchise at Bayer Healthcare and Senior Vice President and Head of Global Oncology at Bristol-Myers Squibb. He is a seasoned biopharmaceutical executive with over 30 years of extensive leadership experience in commercial strategy and execution. He has a proven track record of launching multi-billion-dollar products, building and growing blockbuster drug franchises, and expanding market presence for various oncology products. Financial Highlights Cash and Cash Equivalents & Short-term Investments • Aggregate cash and cash equivalents and short-term investments were $361.3 million and $412.3 million at March 31, 2025 and December 31, 2024, respectively. GAAP and Non-GAAP Research and Development (R&D) Expenses • GAAP R&D expenses according to generally accepted accounting principles in the U.S. (“GAAP”) were $51.2 million for the first quarter of 2025, compared to $30.9 million for the same period of the prior year. • Non-GAAP R&D expenses were $47.1 million for the first quarter of 2025, compared to $28.5 million for the same period of the prior year. GAAP and Non-GAAP General and Administrative (G&A) Expenses • GAAP G&A expenses were $15.6 million for the first quarter of 2025, compared to $11.5 million for the same period of the prior year. • Non-GAAP G&A expenses were $8.6 million for the first quarter of 2025, compared to $4.4 million for the same period of the prior year. GAAP and Non-GAAP Operating Expenses • GAAP operating expenses were $66.8 million for the first quarter of 2025, compared to $42.4 million for the same period of the prior year. • Non-GAAP operating expenses were $55.7 million for the first quarter of 2025, compared to $32.9 million for the same period of the prior year. The increase is primarily related to the increase in R&D expenses due to

4 expansion of clinical studies and development costs related to ivonescimab and increases in people costs as we continue to build out our team. GAAP and Non-GAAP Net Loss • GAAP net loss in the first quarter of 2025 and 2024 was $62.9 million or $(0.09) per basic and diluted share, and $43.5 million or $(0.06) per basic and diluted share, respectively. • Non-GAAP net loss in the first quarter of 2025 and 2024 was $51.8 million or $(0.07) per basic and diluted share, and $34.0 million or $(0.05) per basic and diluted share, respectively.

5 Use of Non-GAAP Financial Measures This release includes measures that are not in accordance with U.S. generally accepted accounting principles (“Non-GAAP measures”). These Non-GAAP measures should be viewed in addition to, and not as a substitute for, Summit's reported GAAP results, and may be different from Non-GAAP measures used by other companies. In addition, these Non-GAAP measures are not based on any comprehensive set of accounting rules or principles. Summit management uses these non-GAAP measures for internal budgeting and forecasting purposes and to evaluate Summit’s financial performance. Summit management believes the presentation of these Non-GAAP measures is useful to investors for comparing prior periods and analyzing ongoing business trends and operating results. For further information regarding these Non-GAAP measures, please refer to the tables presenting reconciliations of our Non-GAAP results to our U.S. GAAP results and the “Notes on our Non-GAAP Financial Information” that accompany this press release. First Quarter 2025 Earnings Call Summit will host an earnings call this afternoon, Thursday, May 1, 2025, at 4:30pm ET. The conference call will be accessible by dialing (800) 715-9871 (toll-free domestic) or (646) 307-1963 (international) using conference code 4936739. A live webcast and instructions for joining the call are accessible through Summit’s website www.smmttx.com. An archived edition of the webcast will be available on our website after the call. About Ivonescimab Ivonescimab, known as SMT112 in Summit’s license territories, North America, South America, Europe, the Middle East, Africa, and Japan, and as AK112 in China and Australia, is a novel, potential first-in-class investigational bispecific antibody combining the effects of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects associated with blocking VEGF into a single molecule. Ivonescimab displays unique cooperative binding to each of its intended targets with multifold higher affinity to PD-1 when in the presence of VEGF. This could differentiate ivonescimab as there is potentially higher expression (presence) of both PD-1 and VEGF in tumor tissue and the tumor microenvironment (TME) as compared to normal tissue in the body. Ivonescimab’s tetravalent structure (four binding sites) enables higher avidity (accumulated strength of multiple binding interactions) in the TME (Zhong, et al, SITC, 2023). This tetravalent structure, the intentional novel design of the molecule, and bringing these two targets into a single bispecific antibody with cooperative binding qualities have the potential to direct ivonescimab to the tumor tissue versus healthy tissue. The intent of this design, together with a half-life of 6 to 7 days after the first dose (Zhong, et al, SITC, 2023), is to improve upon previously established efficacy thresholds, in addition to side effects and safety profiles associated with these targets. Ivonescimab was engineered by Akeso Inc. (HKEX Code: 9926.HK) and is currently engaged in multiple Phase III clinical trials. Over 2,300 patients have been treated with ivonescimab in clinical studies globally. Summit has begun its clinical development of ivonescimab in non-small cell lung cancer (NSCLC), commencing enrollment in 2023 in two multi-regional Phase III clinical trials, HARMONi and HARMONi-3, and the Company has begun to enroll patients in the United States for HARMONi-7. HARMONi is a Phase III clinical trial which intends to evaluate ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non- squamous NSCLC who have progressed after treatment with a 3rd generation EGFR TKI (e.g., osimertinib).

6 Enrollment in HARMONi was completed in the second half of 2024, and top-line results are expected to be announced in the middle of this year. HARMONi-3 is a Phase III clinical trial which is intended to evaluate ivonescimab combined with chemotherapy compared to pembrolizumab combined with chemotherapy in patients with first-line metastatic, squamous and non-squamous NSCLC. HARMONi-7 is a Phase III clinical trial which is intended to evaluate ivonescimab monotherapy compared to pembrolizumab monotherapy in patients with first-line metastatic NSCLC whose tumors have high PD-L1 expression. In addition, Akeso has recently had positive read-outs in three single-region (China), randomized Phase III clinical trials for ivonescimab in NSCLC: HARMONi-A, HARMONi-2, and HARMONi-6. HARMONi-A was a Phase III clinical trial which evaluated ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who have progressed after treatment with an EGFR TKI. HARMONi-2 is a Phase III clinical trial evaluating monotherapy ivonescimab against monotherapy pembrolizumab in patients with locally advanced or metastatic NSCLC whose tumors have positive PD-L1 expression. HARMONi-6 is a Phase III clinical trial evaluating ivonescimab in combination with platinum-based chemotherapy compared with tislelizumab, an anti-PD-1 antibody, in combination with platinum-based chemotherapy in patients with locally advanced or metastatic squamous NSCLC, irrespective of PD-L1 expression. Ivonescimab is an investigational therapy that is not approved by any regulatory authority in Summit’s license territories, including the United States and Europe. Ivonescimab was initially approved for marketing authorization in China in May 2024, and its label was expanded in China in April 2025. Ivonescimab was granted Fast Track designation by the US Food & Drug Administration (“FDA”) for the HARMONi clinical trial setting. About Summit Therapeutics Summit Therapeutics Inc. is a biopharmaceutical oncology company focused on the discovery, development, and commercialization of patient-, physician-, caregiver- and societal-friendly medicinal therapies intended to improve quality of life, increase potential duration of life, and resolve serious unmet medical needs. Summit was founded in 2003 and our shares are listed on the Nasdaq Global Market (symbol "SMMT"). We are headquartered in Miami, Florida, and we have additional offices in Menlo Park, California, and Oxford, UK. For more information, please visit https://www.smmttx.com and follow us on X @SMMT_TX.

7 Contact Summit Investor Relations: Dave Gancarz Chief Business & Strategy Officer Nathan LiaBraaten Senior Director, Investor Relations investors@smmttx.com media@smmttx.com Summit Forward-looking Statements Any statements in this press release about the Company’s future expectations, plans and prospects, including but not limited to, statements about the clinical and preclinical development of the Company’s product candidates, entry into and actions related to the Company’s partnership with Akeso Inc., the Company's anticipated spending and cash runway, the therapeutic potential of the Company’s product candidates, the potential commercialization of the Company’s product candidates, the timing of initiation, completion and availability of data from clinical trials, the potential submission of applications for marketing approvals, potential acquisitions, statements about the previously disclosed At-The-Market equity offering program (“ATM Program”), the expected proceeds and uses thereof, and other statements containing the words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "would," and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including the Company’s ability to sell shares of our common stock under the ATM Program, the conditions affecting the capital markets, general economic, industry, or political conditions, the results of our evaluation of the underlying data in connection with the development and commercialization activities for ivonescimab, the outcome of discussions with regulatory authorities, including the Food and Drug Administration, the uncertainties inherent in the initiation of future clinical trials, availability and timing of data from ongoing and future clinical trials, the results of such trials, and their success, global public health crises, that may affect timing and status of our clinical trials and operations, whether preliminary results from a clinical trial will be predictive of the final results of that trial or whether results of early clinical trials or preclinical studies will be indicative of the results of later clinical trials, whether business development opportunities to expand the Company’s pipeline of drug candidates, including without limitation, through potential acquisitions of, and/or collaborations with, other entities occur, expectations for regulatory approvals, laws and regulations affecting government contracts and funding awards, availability of funding sufficient for the Company’s foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the "Risk Factors" section of filings that the Company makes with the Securities and Exchange Commission. Any change to our ongoing trials could cause delays, affect our future expenses, and add uncertainty to our commercialization efforts, as well as to affect the likelihood of the successful completion of clinical development of ivonescimab. Accordingly, readers should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this press release represent the Company’s views only as of the date of this release and should not be relied upon as representing the Company’s views as of any subsequent date. The Company specifically disclaims any obligation to update any forward-looking statements included in this press release.

9 Summit Therapeutics Inc. GAAP Condensed Consolidated Statements of Operations (in millions, except per share data) Unaudited Three Months Ended March 31, 2025 2024 Operating expenses: Research and development $ 51.2 $ 30.9 General and administrative 15.6 11.5 Total operating expenses 66.8 42.4 Other income 3.9 2.0 Interest expense — (3.1) Net loss $ (62.9) $ (43.5) Net loss per share attributable to common shareholders per share, basic and diluted $ (0.09) $ (0.06) Summit Therapeutics Inc. GAAP Condensed Consolidated Balance Sheet Information (in millions) Unaudited March 31, 2025 December 31, 2024 Cash and cash equivalents and short-term investments $ 361.3 $ 412.3 Total assets $ 383.8 $ 435.6 Total liabilities $ 39.5 $ 46.8 Total stockholders' equity $ 344.3 $ 388.7

10 Summit Therapeutics Inc. GAAP Condensed Consolidated Statement of Cash Flows Information (in millions) Unaudited Three Months Ended March 31, 2025 2024 Net cash used in operating activities $ (61.1) $ (30.1) Net cash provided by investing activities 160.1 19.8 Net cash provided by financing activities 7.7 0.5 Effect of exchange rates on cash and cash equivalents 0.0 0.0 Increase (decrease) in cash, cash equivalents and restricted cash $ 106.7 $ (9.8)

11 Summit Therapeutics Inc. Schedule Reconciling Selected Non-GAAP Financial Measures (in millions, except per share data) Unaudited Three Months Ended March 31, 2025 2024 Reconciliation of GAAP to Non-GAAP Research and Development Expense GAAP Research and development $ 51.2 $ 30.9 Stock-based compensation (Note 1) (4.1) (2.4) Non-GAAP Research and development $ 47.1 $ 28.5 Reconciliation of GAAP to Non-GAAP General and Administrative Expenses GAAP General and administrative $ 15.6 $ 11.5 Stock-based compensation (Note 1) (7.0) (7.1) Non-GAAP General and administrative $ 8.6 $ 4.4 Reconciliation of GAAP to Non-GAAP Operating Expenses GAAP Operating expenses $ 66.8 $ 42.4 Stock-based compensation (Note 1) (11.1) (9.5) Non-GAAP Operating expense $ 55.7 $ 32.9 Reconciliation of GAAP Net Loss to Non-GAAP Net Loss GAAP Net Loss $ (62.9) $ (43.5) Stock-based compensation (Note 1) 11.1 9.5 Non-GAAP Net Loss $ (51.8) $ (34.0) Reconciliation of GAAP Net Loss to Non-GAAP Net Loss Per Common Share GAAP Net Loss Per Basic and Diluted Common Share $ (0.09) $ (0.06) Stock-based compensation (Note 1) 0.02 0.01 Non-GAAP Net loss Per Basic and Diluted Common Share $ (0.07) $ (0.05) Basic and Diluted Common Shares 738.1 701.8

12 Summit Therapeutics Inc. Schedule Reconciling Selected Non-GAAP Financial Measures (in millions) Three Months Ended March 31, 2025 December 31, 2024 September 30, 2024 June 30, 2024 March 31, 2024 Reconciliation of GAAP to Non-GAAP Operating Expenses GAAP Operating expenses $ 66.8 $ 65.6 $ 58.4 $ 59.6 $ 42.4 Stock-based compensation (Note 1) (11.1) (11.0) (19.4) (11.1) — (9.5) Non-GAAP Operating Expense (Note 2) $ 55.7 $ 54.6 $ 39.0 $ 48.5 $ 32.9 Reconciliation of GAAP Net Loss to Non-GAAP Net Loss GAAP Net Loss $ (62.9) $ (61.2) $ (56.3) $ (60.4) $ (43.5) Stock-based compensation (Note 1) 11.1 11.0 19.4 11.1 9.5 Non-GAAP Net Loss (Note 2) $ (51.8) $ (50.2) $ (36.9) $ (49.3) $ (34.0)

13 Summit Therapeutics Inc. Notes on our Non-GAAP Financial Information Non-GAAP financial measures adjust GAAP financial measures for the items listed below. These Non-GAAP measures should be viewed in addition to, and not as a substitute for Summit's reported GAAP results, and may be different from Non-GAAP measures used by other companies. In addition, these Non-GAAP measures are not based on any comprehensive set of accounting rules or principles. Summit management uses these non-GAAP measures for internal budgeting and forecasting purposes and to evaluate Summit’s financial performance. Summit management believes the presentation of these Non-GAAP measures is useful to investors for comparing prior periods and analysing ongoing business trends and operating results. Each of non-GAAP Research and Development Expense, non-GAAP General and Administrative Expenses, non- GAAP Operating Expenses, Non-GAAP Net Loss and Non-GAAP EPS differ from GAAP in that such measures exclude the non-cash charges and costs associated with stock-based compensation. Note 1: Stock-based compensation is a non-cash charge and costs calculated for this expense can vary year-over- year depending on the stock price of awards on the date of grant as well as the timing of compensation award arrangements. Note 2: Beginning in the fourth quarter of 2024, the Company’s non-GAAP financial measures will no longer exclude acquired in-process research and development expenses (“IPR&D”). Non-GAAP financial measures for the three months ended June 30, 2024 previously excluded $15.0 million of IPR&D which represented an upfront payment made to Akeso under an amendment to the Collaboration and License Agreement. Prior period amounts have been revised to conform to the current period presentation.

14 Appendix: Glossary of Critical Terms Contained Herein Affinity – Affinity is the strength of binding of a molecule, such as a protein or antibody, to another molecule, such as a ligand. Avidity – Avidity is the accumulated strength of multiple binding interactions. Angiogenesis – Angiogenesis is the development, formation, and maintenance of blood vessel structures. Without sufficient blood flow, tissue may experience hypoxia (insufficient oxygen) or lack of nutrition, which may cause cell death.1 Cooperative binding – Cooperative binding occurs when the number of binding sites on the molecule that can be occupied by a specific ligand (e.g., protein) is impacted by the ligand’s concentration. For example, this can be due to an affinity for the ligand that depends on the amount of ligand bound or the binding strength of the molecule to one ligand based on the concentration of another ligand, increasing the chance of another ligand binding to the compound.2 Immunotherapy – Immunotherapy is a type of treatment, including cancer treatments, that help a person’s immune system fight cancer. Examples include anti-PD-1 therapies.3 Intracranial - Within the cranium or skull. PD-1 – Programmed cell Death protein 1 is a protein on the surface of T cells and other cells. PD-1 plays a key role in reducing the regulation of ineffective or harmful immune responses and maintaining immune tolerance. However, with respect to cancer tumor cells, PD-1 can act as a stopping mechanism (a brake or checkpoint) by binding to PD-L1 ligands that exist on tumor cells and preventing the T cells from targeting cancerous tumor cells.4 PD-L1 – Programmed cell Death Ligand 1 is expressed by cancerous tumor cells as an adaptive immune mechanism to escape anti-tumor responses, thus believed to suppress the immune system’s response to the presence of cancer cells.5 PD-L1 TPS – PD-L1 Tumor Proportion Score represents the percentage of tumor cells that express PD-L1 proteins. PFS – Progression-Free Survival. RANO – Response Assessment in Neuro-Oncology, the standard for assessing the response of a brain or spinal cord tumor to therapy. SQ-NSCLC – Non-small cell lung cancer tumors of squamous histology. 1 Shibuya M. Vascular Endothelial Growth Factor (VEGF) and Its Receptor (VEGFR) Signaling in Angiogenesis: A Crucial Target for Anti- and Pro-Angiogenic Therapies. Genes Cancer. 2011 Dec;2(12):1097-105 2 Stefan MI, Le Novère N. Cooperative binding. PLoS Comput Biol. 2013;9(6) 3 US National Cancer Institute, a part of the National Institute of Health (NIH). https://www.cancer.gov/about-cancer/treatment/types/immunotherapy. Accessed April 2024. 4 Han Y, et al. PD-1/PD-L1 Pathway: Current Researches in Cancer. Am J Cancer Res. 2020 Mar 1;10(3):727-742. 5 Han Y, et al. PD-1/PD-L1 Pathway: Current Researches in Cancer. Am J Cancer Res. 2020 Mar 1;10(3):727-742.

15 T Cells – T cells are a type of white blood cell that is a component of the immune system that, in general, fights against infection and harmful cells like tumor cells.6 Tetravalent – A tetravalent molecule has four binding sites or regions. Tumor Microenvironment – The tumor microenvironment is the ecosystem that surrounds a tumor inside the body. It includes immune cells, the extracellular matrix, blood vessels and other cells, like fibroblasts. A tumor and its microenvironment constantly interact and influence each other, either positively or negatively.7 VEGF – Vascular Endothelial Growth Factor is a signaling protein that promotes angiogenesis.8 6 Cleveland Clinic. https://my.clevelandclinic.org/health/body/24630-t-cells. Accessed April 2024. 7 MD Anderson Cancer Center. https://www.mdanderson.org/cancerwise/what-is-the-tumor-microenvironment-3-things-to-know.h00-159460056.html. Accessed April 2024. 8 Shibuya M. Vascular Endothelial Growth Factor (VEGF) and Its Receptor (VEGFR) Signaling in Angiogenesis: A Crucial Target for Anti- and Pro-Angiogenic Therapies. Genes Cancer. 2011 Dec;2(12):1097-105.

q12025earningsdeck_final

Summit Therapeutics Q1 2025 Earnings Call May 1, 2025 4:30pm ET

Forward Looking Statement Any statements in this presentation about the Company’s future expectations, plans and prospects, including but not limited to, statements about the clinical and preclinical development of the Company’s product candidates, entry into and actions related to the Company’s partnership with Akeso Inc., the Company’s anticipated spending and cash runway, the therapeutic potential of the Company’s product candidates, the potential commercialization of the Company’s product candidates, the timing of initiation, completion and availability of data from clinical trials, the potential submission of applications for marketing approvals, potential acquisitions, statements about the previously disclosed At-The-Market equity offering program (“ATM Program”), the expected proceeds and uses thereof, and other statements containing the words "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "plan," "potential," "predict," "project," "should," "target," "would," and similar expressions, constitute forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including the results of our evaluation of the underlying data in connection with the development and commercialization activities for ivonescimab, the outcome of discussions with regulatory authorities, including the Food and Drug Administration, the uncertainties inherent in the initiation of future clinical trials, availability and timing of data from ongoing and future clinical trials, the results of such trials, and their success, and global public health crises that may affect timing and status of our clinical trials and operations, whether preliminary results from a clinical trial will be predictive of the final results of that trial or whether results of early clinical trials or preclinical studies will be indicative of the results of later clinical trials, whether business development opportunities to expand the Company’s pipeline of drug candidates, including without limitation, through potential acquisitions of, and/or collaborations with, other entities occur, expectations for regulatory approvals, laws and regulations affecting government contracts and funding awards, availability of funding sufficient for the Company’s foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the "Risk Factors" section of filings that the Company makes with the Securities and Exchange Commission. Any change to our ongoing trials could cause delays, affect our future expenses, and add uncertainty to our commercialization efforts, as well as to affect the likelihood of the successful completion of clinical development of ivonescimab. Accordingly, the audience should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this presentation represent the Company’s views only as of the date of this presentation and should not be relied upon as representing the Company’s views as of any subsequent date. The Company specifically disclaims any obligation to update any forward-looking statements included in this presentation. Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call - May 2025 2

Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Data generated and analyzed by Akeso. z Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call - May 2025 3 1 Q1 2025 Highlights Enrollment completed Oct 2024, topline data expected mid-2025 Initial enrollment begun and activation of additional sites ongoing Enrollment and activation of additional sites ongoing Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). ISTs have begun enrolling ISTs Two studies are open and enrolling: cSCC and GBM MD Anderson Collab Pfizer Collaboration Clinical trials expected to start later this year ISTs: Investigator Sponsored Trials; HA: Health Authority; cSCC: Cutaneous Squamous Cell Carcinoma; GBM: Glioblastoma Ivonescimab Collaborations Progressing & Expanding: Ivonescimab + chemo achieved stat sig superiority in PFS vs. PD-1 plus chemo in 1L Squamous NSCLC Ivonescimab monotherapy approved in China in 1L NSCLC PD-L1+; OS HR 0.777 at early HA-requested interim analysis

Phase I-II Phase III 2L+ EGFRm NSCLC: 1L NSCLC: 1L NSCLC: 1L R/M HNSCC: 1L Biliary Tract: 1L Pancreatic: Conducted in China Fully Sponsored and Managed by Akeso 4 Summit Confidential & Proprietary Information – Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA) Ivonescimab Pipeline 30+ Approved ISTs, 2 now enrolling Investigator Sponsored Trials Phase III Further Announcements in 2025 Expanding CDP M.D. Anderson Collaboration 2L+ EGFRm NSCLC: 1L NSCLC: 1L NSCLC: Planned and Ongoing Studies Sponsored by Summit Therapeutics* Not shown in image Not shown in image 2 trials now enrolling in cSCC, GBM Not shown in image *ISTs, M.D. Anderson collaboration trials, Pfizer collaboration trials not sponsored by Summit. Akeso Phase III clinical trials from Akeso's 2024 First Half Interim Results (prnewswire.com; akesobio.com) and/or clinicaltrials.gov. Abbreviations: ISTs, Investigator sponsored trials; NSCLC, non small cell lung cancer; GI, gastrointestinal; G/GEJ, Gastric / Gastroesophageal Junction; SCLC, small cell lung cancer; HNSCC, Head and neck squamous cell carcinoma; CDP, clinical development plan. 2L+ NSCLC: NSCLC Ovarian G/GEJ SCLC Hepatocellular Colorectal Pfizer Collaboration 1L TNBC:

China Ivonescimab Catalysts in 2025 Ivonescimab + Chemo vs. Tislelizumab + Chemo in 1L NSCLC Ivo monotherapy: clinically meaningful early OS trend vs. pembro monotherapy (OS HR = 0.777 at 39% maturity based on health authority- requested interim analysis)2 Ivo + chemo achieved statistically & clinically meaningful PFS benefit over PD-1 + chemo (tislelizumab + chemo)3 Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 5 Global Ivo’s first global Phase III trial results expected mid-20251 References: 1. Summit Therapeutics Inc JPM presentation on January 13, 2025. 2. Summit Therapeutics Inc press release on April 25, 2025. 3. Summit Therapeutics Inc press release on April 23, 2025. Ivonescimab vs. Pembrolizumab in 1L PD-L1+ NSCLC Ivonescimab + Chemo vs. Chemo in 2L+ EGFRm NSCLC Mid-2025

Abbreviations: NSCLC, non-small cell lung cancer; PD- L1, programmed cell death-ligand; Q3W, every three weeks; PFS, progression free survival; OS, overall survival; ORR, overall response rate; DCR, disease control rate; DOR, duration of response; BICR, blinded independent central review; 1L, first-line. Ivonescimab + Chemo vs. Pembrolizumab + Chemo Randomized, Double-blind, Phase III Study 1L NSCLC: PD-L1 All-Comers* NCT05899608 Key Inclusion • 1L squamous or non-squamous metastatic NSCLC • Regardless of PD-L1 expression • No activating genomic alterations Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). * PFS by BICR is a sensitivity analysis Primary • OS, PFS by Investigator Secondary • ORR, DCR, DOR, safety and tolerability • PFS by BICR* Study Endpoints Ivonescimab + Carboplatin + Paclitaxel (or nab-paclitaxel) + Q3W x 4 cycles Pembrolizumab + Carboplatin + Paclitaxel (or nab-paclitaxel) Q3W x 4 cycles Treatment Until: • Intolerable toxicity, • Disease progression, • 24 months of treatment Ivonescimab + Carboplatin + Pemetrexed Q3W x 4 cycles Pembrolizumab + Carboplatin + Pemetrexed, Q3W x 4 cycles 1:1 R a n d o m iz a ti o n Squamous Non-Squamous OR Maintenance n = ~1080 S a fety a n d S u rv iv a l F o llo w -u pSquamous: Pembrolizumab Squamous: Ivonescimab Non-Squamous: Pembrolizumab + Pemetrexed Non-Squamous: Ivonescimab + Pemetrexed Stratification Factors Include Histology Squamous vs. Non-Squamous Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 6 Summit Sponsored Study

Summit Sponsored Study Abbreviations: NSCLC, non-small cell lung cancer; PD- L1, programmed cell death-ligand 1; Q3W, every three weeks; PFS, progression free survival; OS, overall survival; ORR, overall response rate; 1L, first-line Randomized, Double-blind, Phase III Study 1L NSCLC with PD-L1 High Expression NCT067675141 Key Inclusion • 1L squamous or non-squamous metastatic NSCLC • PD-L1 high expression • No activating genomic alterations Monotherapy Ivonescimab vs. Pembrolizumab Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). 1. HARMONi-7. ClinicalTrials.gov identifier: NCT06767514 Updated Jan 10, 2025, Accessed on Jan. 10, 2025 Study Details | Clinical Study of Ivonescimab for First-line Treatment of Metastatic NSCLC Patients With High PD-L1 | ClinicalTrials.gov Treatment Until • Intolerable toxicity, • Disease progression, • 24 months of treatmentPembrolizumab 200 mg Q3W Ivonescimab 20 mg/kg Q3W (N=780) 1:1 R a n d o m iz a ti o n S a fety a n d S u rv iv a l F o llo w -u p Study Endpoints Primary endpoints: PFS, OS Secondary endpoints: ORR, safety and tolerability Stratification Factors Include Histology Squamous vs. Non-Squamous Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 7

2028 Estimated CPI TAM2 Approved Anti PD-(L)1 & Anti-VEGF Therapies Approved Anti PD-(L)1 Therapies Approved Anti-VEGF Therapies 50+ Approved Indications for PD-(L)1 & VEGF Therapies 1 $90B+ NSCLC CPI TAM2,3$20B+ Ivonescimab Clinical TrialsIvonescimab Opportunity Goes Beyond Checkpoint Inhibitors (CPI) 1. Data from cancer.gov updated 2024 2. IQVIA MIDAS Disease, Dec 2023; IQVIA Institute Apr 2024. 3. TD Cowen; Investors Guide to Immuno-Oncology; Sept 6, 2023; Abbreviations: PD-(L)1, programmed cell death- (ligand) 1; PD-1, programmed cell death protein 1; VEGF, vascular endothelial growth factor; TAM, Total Addressable Market; Ph, phase; Ivo, ivonescimab.; CPI, checkpoint inhibitor Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 8

Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 9 Financial Summary As of March 31, 2025 Cash & Investments : ~$361 Million Current Debt: $0 Common Shares Outstanding: ~742 Million

Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 10 (1) Excludes stock-based compensation Refer to the next slides for reconciliations between Generally Accepted Accounting Principles (GAAP) and Non-GAAP financial measures. Financial Summary Q1’25 vs. Q4’24 (1) Excludes stock-based compensation

Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 11 Schedule Reconciling Selected Non-GAAP Financial Measures Note 1: Stock-based compensation is a non-cash charge and costs calculated for this expense can vary year-over-year depending on the stock price of awards on the date of grant as well as the timing of compensation award arrangements.

Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Summit Confidential & Proprietary Information Do Not Copy or Distribute Presentation Summit Therapeutics Q1 2025 Earnings Call – May 2025 12 Schedule Reconciling Selected Non-GAAP Financial Measures Note 1: Stock-based compensation is a non-cash charge and costs calculated for this expense can vary year-over-year depending on the stock price of awards on the date of grant as well as the timing of compensation award arrangements.

Summit Therapeutics Q1 2025 Earnings Call May 1, 2025 4:30pm ET