Form 8-K - Current report

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): October 30, 2024


Summit Therapeutics Inc.
(Exact Name of Registrant as Specified in Its Charter)

Delaware	001-36866	37-1979717
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer 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 October 30, 2024, Summit Therapeutics Inc. (the “Company”) issued a press release announcing its financial results and operational progress for the third quarter ended September 30, 2024. 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 9:00am ET on October 30, 2024 to announce its third quarter 2024 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 Item 7.01 and in Exhibit 99.2 shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, as amended, 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 October 30, 2024
99.2			Presentation Slides for October 30, 2024 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: October 30, 2024	By:	/s/ Manmeet S. Soni
		Chief Operating Officer and Chief Financial Officer
		(Principal Financial Officer)

Summit Therapeutics Reports Operational Progress and Financial Results for the Third Quarter and Nine Months Ended September 30, 2024 Ivonescimab Monotherapy Became First Drug to Achieve Clinically Meaningful Benefit over Pembrolizumab Monotherapy in a Phase III Randomized Clinical Trial in NSCLC, HARMONi-2, Reducing Risk of Disease Progression or Death by 49% in First-Line PD-L1 Positive Advanced NSCLC in China Enrollment Completed in Global Phase III HARMONi Trial in 2L+ EGFRm Advanced NSCLC; Received Fast Track Designation from FDA; Topline Data Expected in Mid-2025 Summit Intends to Expand HARMONi-3 Global Phase III Trial in 1L Metastatic NSCLC to Include Patients with Tumors of Non-Squamous Histology in Addition to Currently Enrolling Squamous Patients Summit to Initiate Global Phase III HARMONi-7 Trial in 1L PD-L1 High, Metastatic NSCLC in Early 2025 Encouraging Ivonescimab Phase II Data from China Featured at ESMO 2024 and WCLC 2024, Supports Continued Expansion of Clinical Development of Ivonescimab Outside of Metastatic NSCLC Raised $235 Million in Private Financing from Insiders & Leading Biopharma Institutional Investors Miami, Florida, October 30, 2024 - Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today reported an update on its operational progress and financial results for the third quarter and nine months ended September 30, 2024. Operational & Corporate Updates Our 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:  Since in-licensing ivonescimab in January 2023, we have launched a late-stage clinical development program in non-small cell lung cancer (NSCLC) comprised of two registrational Phase III trials in the following proposed indications: o 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).  Enrollment has completed with topline data expected in mid-2025; Fast Track Designation was granted by the US FDA for ivonescimab in this setting. o HARMONi-3: Ivonescimab combined with chemotherapy in first-line metastatic squamous NSCLC patients without actionable genomic alterations.

 Summit intends to amend the protocol to include patients with both squamous and non- squamous histologies.  As part of the trial amendment, the primary endpoint is intended to be updated to include two primary endpoints: progression-free survival (PFS) and overall survival (OS). Accordingly, Summit intends to update the total sample size for the randomized, multi- regional Phase III clinical trial to include an estimated 1,080 patients.  As a reminder, updated Phase II data from this setting was announced at the 2024 European Lung Cancer Conference (ELCC 2024) in March from the AK112-201 clinical trial centered around the cohort of patients in which ivonescimab was combined with chemotherapy for first-line treatment of squamous and non-squamous advanced or metastatic NSCLC in patients without actionable genomic alterations. This data was generated and analyzed by our collaboration and licensing partner, Akeso Inc. (Akeso, HKEX Code: 9926.HK).  First-line patients with advanced or metastatic non-squamous tumors (n=72) experienced a median PFS of 13.3 months (95% CI: 8.3 – 16.4 months). In addition, first-line advanced or metastatic squamous NSCLC patients (n=63) experienced a median PFS of 11.1 months (95% CI: 9.5 – 16.3 months). Both metrics are encouraging considering the expectations for the current standards of care. Median OS was not reached in either subset of patients after a median follow-up time of 22.1 months. The frequency of treatment-related adverse events (TRAEs) leading to the discontinuation of ivonescimab was 11.1% and 2.8%, respectively, in patients with squamous and non-squamous tumors.  In addition, we have announced our intention to launch a third Phase III clinical trial in the following proposed indication, with trial initiation expected in early 2025: o HARMONi-7: Ivonescimab monotherapy in first-line metastatic NSCLC patients whose tumors have high PD-L1 expression without actionable genomic alterations.  The sample size for this study is currently planned to be an estimated 780 patients with two primary endpoints, PFS and OS.  In early September 2024, positive results were announced from the Phase III HARMONi-2 trial which were subsequently presented at the Presidential Symposium at the International Association for the Study of Lung Cancer’s (IASLC) 2024 World Conference on Lung Cancer (WCLC 2024). HARMONi-2, a single- region, randomized, multi-center double-blinded Phase III study in patients with locally advanced or metastatic NSCLC whose tumors have positive PD-L1 expression, achieved its primary endpoint of PFS for patients receiving ivonescimab monotherapy vs. those receiving pembrolizumab monotherapy. The HARMONi-2 trial was conducted in China and sponsored by Akeso with data generated and analyzed by Akeso.

o Patients (n=398) receiving ivonescimab experienced a 49% reduction in disease progression or death as compared to pembrolizumab (HR: 0.51, 95% CI: 0.38 - 0.69; p<0.0001). Median PFS of 11.1 months vs. 5.8 months was observed in patients administered ivonescimab vs. pembrolizumab. A clinically meaningful benefit was demonstrated across pre-specified clinical subgroups, including those with PD-L1 low expression, PD-L1 high expression, squamous and non-squamous histologies, as well as other high-risk patients. Both the overall response rate (ORR) measured according to RECIST v1.1 criteria, as well as the disease control rate (DCR), were higher in patients treated with ivonescimab compared to those treated with pembrolizumab. OS data was not yet mature at the time of the data cutoff and will be evaluated in the future. Ivonescimab demonstrated an acceptable and manageable safety profile, which was consistent with previous studies.  Additionally, encouraging perioperative NSCLC Phase II data was featured at WCLC 2024 from AK112- 205, a single-region (China), multi-center, open-label study of patients with Stage II or III resectable NSCLC, with data generated and analyzed by Akeso. The study was designed to assess patients receiving either ivonescimab monotherapy or ivonescimab plus chemotherapy prior to surgical resection and then ivonescimab monotherapy after surgery. Due to the maturity of the data and the timing of the data cutoff, the results were mature for the neo-adjuvant portion of the clinical trial. o At the time of data cutoff, 49 patients had been enrolled into the ivonescimab plus chemotherapy arm in the neo-adjuvant setting; of these 49 patients, 39 went on to complete surgery. Of the 39 patients who received ivonescimab plus chemotherapy in the neo-adjuvant stage and completed surgery, 71.8% of patients experienced a major pathological response (MPR) and 43.6% of patients experienced a pathological complete response (pCR). In the 49 patients enrolled in this cohort, median event-free survival (EFS) was not yet reached after 8.9 months of median follow- up time; the 12-month EFS rate was 80.3% (95% CI: 59.6, 91.1). These results are encouraging compared to the historical data that has been observed in global pivotal studies in a similar setting. The safety profile in this Phase II study was acceptable and manageable.  In September 2024, promising anti-tumor activity and safety data for ivonescimab were presented at the 2024 European Society for Medical Oncology Annual Meeting (ESMO 2024) featuring updated data in advanced triple-negative breast cancer (TNBC), recurrent / metastatic head and neck squamous cell carcinoma (HNSCC), and metastatic microsatellite-stable (MSS) colorectal cancer (CRC). Each trial from which the data was generated was a Phase II study conducted in China sponsored by Akeso with data generated and analyzed by Akeso. Based on the results of these Phase II data sets as well as data announced earlier in 2024, Summit intends to explore further clinical development of ivonescimab in solid tumor settings outside of metastatic NSCLC, the Company’s current area of focus in its Phase III clinical trials. o Metastatic MSS CRC: The study was designed to assess patients who were randomly assigned to receive ivonescimab plus FOLFOXIRI with or without ligufalimab (anti-CD47 monoclonal antibody). Note that ligufalimab, or AK117, is Akeso’s proprietary, investigational product that is not approved by any regulatory authority, and to which Summit does not have any license or ownership rights. At the time of data cutoff, 22 patients received ivonescimab plus FOLFOXIRI (median follow-up time of 9 months); 18 patients received ivonescimab plus ligufalimab plus

FOLFOXIRI (median follow-up time of 9.6 months). All patients in both groups experienced a reduction in their tumor burden compared to their baseline tumor assessment. The ORR and DCR for the 39 patients combined from both groups who had at least one post-baseline tumor assessment was 84.6% and 100%, respectively. Median progression-free survival was not reached in either group at the time of this analysis. The safety profile in this Phase II study was acceptable and manageable. o Advanced TNBC: The results presented were from the portion of the study intended to assess patients who received ivonescimab plus chemotherapy (either paclitaxel or nab-paclitaxel) with locally advanced or metastatic TNBC. At the time of data cutoff, 30 patients received ivonescimab plus chemotherapy with median follow-up time of 10.1 months. Sixty percent of patients had previously received taxane-based chemotherapy in either the neoadjuvant or adjuvant setting in this Phase II data set. All patients experienced a reduction in their tumor burden compared to their baseline tumor assessment. The ORR and DCR for the 29 patients who had at least one post- baseline tumor assessment were 72.4% and 100%, respectively. Median progression-free survival was 9.3 months as the time of this analysis. The safety profile in this Phase II study was acceptable and manageable. o Recurrent / Metastatic HNSCC: The results presented were from the portion of the study intended to assess patients who received ivonescimab with or without ligufalimab (anti-CD47) with PD-L1 positive, locally advanced or metastatic recurrent / metastatic HNSCC. At the time of data cutoff, 10 patients received ivonescimab (median follow-up: 3.3 months) and 20 patients received ivonescimab plus ligufalimab (median follow-up 4.1 months). Four of 10 patients receiving ivonescimab had a PD-L1 CPS of 1-20; nine of 20 patients administered ivonescimab plus ligufalimab had a PD-L1 CPS of 1-20; the remaining patients in each arm had a PD-L1 CPS >20. The ORR and DCR for the 30 patients was 50.0% and 86.7%, respectively. The safety profile in this Phase II study was acceptable and manageable. Financial Highlights “With the recent financing in September 2024 providing us $235 million, we have strengthened our cash balance to extend our cash runway” said Manmeet S. Soni, Summit’s Chief Operating Officer and Chief Financial Officer. “Our cash balance at quarter end aggregating to $487 million provides us enough cash to continue to invest in the ivonescimab trials planned to be expanded and initiated in 2025.” Cash, Cash Equivalents and Short-term Investments  Aggregate cash and cash equivalents, and short-term investments were approximately $487 million and $186.2 million at September 30, 2024 and December 31, 2023, respectively.  In September 2024, we closed a private financing of $235 million with multiple leading biotech institutional investors and insiders.

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 $37.7 million for the third quarter of 2024, compared to $15.3 million for the same period of the prior year.  Non-GAAP R&D expenses were $31.9 million for the third quarter of 2024, compared to $15.2 million for the same period of the prior year.  The increase is primarily due to expansion of clinical study and development costs related to ivonescimab and increases in people cost as we continue to build out our R&D team. GAAP and Non-GAAP General and Administrative (G&A) Expenses  GAAP G&A expenses were $20.4 million for the third quarter of 2024, compared to $5.4 million for the same period of the prior year.  Non-GAAP G&A expenses were $6.8 million for the third quarter of 2024, compared to $4.8 million for the same period of the prior year. GAAP and Non-GAAP Operating Expenses  GAAP operating expenses were $58.1 million for the third quarter of 2024, compared to $20.7 million for the same period of the prior year. This increase in GAAP operating expenses was primarily related to the increase in stock-based compensation expense during the quarter related to charges related to the achievement of certain market conditions on performance stock option awards and increase in R&D expenses as explained above.  Non-GAAP operating expenses were $38.7 million for the third quarter of 2024, compared to $20.0 million for the same period of the prior year. GAAP and Non-GAAP Net Loss  GAAP net loss in the third quarter of 2024 and 2023 was $56.3 million or $(0.08) per basic and diluted share, and $21.2 million or $(0.03) per basic and diluted share, respectively.  Non-GAAP net loss in the third quarter of 2024 and 2023 was $36.9 million or $(0.05) per basic and diluted share, and $20.5 million or $(0.03) per basic and diluted share, respectively. 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. Third Quarter 2024 Earnings Call Summit will host an earnings call this morning, Wednesday, October 30, 2024, at 9:00am ET. The conference call will be accessible by dialing (800) 715-9871 (toll-free domestic) or (646) 307-1963 (international) using conference code 3934052. 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, 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, 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 when in the presence of both PD-1 and 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 with over 18-fold increased binding affinity to PD-1 in the presence of VEGF in vitro, and over 4-times increased binding affinity to VEGF in the presence of PD-1 in vitro (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 (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 1,800 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, with a plan to initiate HARMONi-7 in early 2025. 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). HARMONi-3 is a Phase III clinical trial which is designed to evaluate ivonescimab combined with chemotherapy compared to pembrolizumab combined with chemotherapy in patients with first-line metastatic squamous NSCLC.

HARMONi-7 is a planned 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 two single-region (China), randomized Phase III clinical trials for ivonescimab in NSCLC, HARMONi-A and HARMONi-2. 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. 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 approved for marketing authorization in China in May 2024. 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 @summitplc. Contact Summit Investor Relations: Dave Gancarz Chief Business & Strategy Officer Nathan LiaBraaten Senior Director, Investor Relations investors@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 intended use of the net proceeds from the private placements, 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, 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, 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.

Summit Therapeutics Inc. GAAP Condensed Consolidated Statements of Operations (Unaudited) (in millions, except per share data) Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Operating expenses: Research and development $ 37.7 $ 15.3 $ 99.4 34.7 Acquired in-process research and development — — 15.0 520.9 General and administrative 20.4 5.4 46.1 18.7 Total operating expenses 58.1 20.7 160.5 574.3 Other operating (expense) income, net (0.3) 0.3 0.1 0.8 Operating loss (58.4) (20.4) (160.4) (573.5) Other income (expense), net 2.1 (0.8) 0.3 (4.9) Net loss $ (56.3) $ (21.2) $ (160.1) $ (578.4) Net loss per share attributable to common shareholders, basic and diluted $ (0.08) $ (0.03) $ (0.22) $ (0.98) Summit Therapeutics Inc. GAAP Condensed Consolidated Balance Sheet Information (in millions) Unaudited September 30, 2024 December 31, 2023 Cash and cash equivalents, and short-term investments $ 487.0 $ 186.2 Total assets $ 502.8 $ 202.9 Total liabilities $ 64.9 $ 125.2 Total stockholders' equity $ 437.9 $ 77.7

Summit Therapeutics Inc. GAAP Condensed Consolidated Statements of Cash Flows Information (in millions) Unaudited Nine Months Ended September 30, 2024 2023 Net cash used in operating activities $ (93.4) $ (57.3) Net cash used in investing activities (288.8) (648.3) Net cash provided by financing activities 404.8 80.3 Effect of exchange rate changes on cash 0.1 0.5 Increase (decrease) in cash and cash equivalents $ 22.7 $ (624.8)

Summit Therapeutics Inc. Schedule Reconciling Selected Non-GAAP Financial Measures (Unaudited) (in millions, except per share data) Three Months Ended September 30, Nine Months Ended September 30, 2024 2023 2024 2023 Reconciliation of GAAP to Non-GAAP Research and Development Expense GAAP Research and development $ 37.7 $ 15.3 $ 99.4 $ 34.7 Stock-based compensation (Note 1) (5.8) (0.1) (11.7) (2.0) Non-GAAP Research and development $ 31.9 $ 15.2 $ 87.7 $ 32.7 Reconciliation of GAAP to Non-GAAP General and Administrative Expenses GAAP General and administrative $ 20.4 $ 5.4 $ 46.1 $ 18.7 Stock-based compensation (Note 1) (13.6) (0.6) (28.2) (3.4) Non-GAAP General and administrative $ 6.8 $ 4.8 $ 17.9 $ 15.3 Reconciliation of GAAP to Non-GAAP Acquired In-Process Research and Development Expenses GAAP Acquired In-process research and development $ — $ — $ 15.0 $ 520.9 Acquired In-process research and development (Note 2) — — (15.0) (520.9) Non-GAAP Acquired In-process research and development $ — $ — $ — $ — Reconciliation of GAAP Net Loss to Non-GAAP Net Loss GAAP Net Loss $ (56.3) $ (21.2) $ (160.1) $ (578.4) Stock-based compensation (Note 1) 19.4 0.7 39.9 5.4 Acquired In-process research and development (Note 2) — — 15.0 520.9 Non-GAAP Net Loss $ (36.9) $ (20.5) $ (105.2) $ (52.1) Reconciliation of GAAP Net Loss to Non-GAAP Net Loss Per Common Share GAAP Net Loss Per Basic and Diluted Common Share $ (0.08) $ (0.03) $ (0.22) $ (0.98) Stock-based compensation (Note 1) 0.03 — 0.06 0.01 Acquired In-process research and development (Note 2) — — 0.02 0.88 Non-GAAP Net loss Per Basic and Diluted Common Share $ (0.05) $ (0.03) $ (0.14) $ (0.09) Basic and Diluted Common Shares 726.7 697.7 712.2 592.4

Summit Therapeutics Inc. Schedule Reconciling Selected Non-GAAP Financial Measures (in millions) Unaudited Three Months Ended September 30, 2024 June 30, 2024 March 31, 2024 December 31, 2023 September 30, 2023 Reconciliation of GAAP to Non-GAAP Operating Expenses GAAP Operating expenses $ 58.1 $ 59.8 $ 42.6 $ 36.4 $ 20.7 Stock-based compensation (Note 1) (19.4) (11.1) (9.5) — (8.7) — (0.7) Acquired In-process research and development (Note 2) — (15.0) — — — Non-GAAP Operating Expense $ 38.7 $ 33.7 $ 33.1 $ 27.7 $ 20.0 Reconciliation of GAAP Net Loss to Non-GAAP Net Loss GAAP Net Loss $ (56.3) $ (60.4) $ (43.5) $ (36.6) $ (21.2) Stock-based compensation (Note 1) 19.4 11.1 9.5 8.7 0.7 Acquired In-process research and development (Note 2) — 15.0 — — — Non-GAAP Net Loss $ (36.9) $ (34.3) $ (34.0) $ (27.9) $ (20.5)

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 analyzing 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. In addition, non- GAAP Acquired In-Process Research and Development Expenses, non-GAAP Operating Expenses, non-GAAP Net Loss and non-GAAP EPS each exclude certain one-time charges associated with acquired in-process research and development, in each case as described further in the notes below and as expressed in the tabular reconciliation presented above. 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: Acquired in-process research and development represents a one-time charge associated with the Company's in-licensing of ivonescimab from Akeso.

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 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. 1Shibuya 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 2Stefan MI, Le Novère N. Cooperative binding. PLoS Comput Biol. 2013;9(6) 3US National Cancer Institute, a part of the National Institute of Health (NIH). https://www.cancer.gov/about-cancer/treatment/types/immunotherapy. Accessed April 2024. 4Han Y, et al. PD-1/PD-L1 Pathway: Current Researches in Cancer. Am J Cancer Res. 2020 Mar 1;10(3):727-742. 5Han Y, et al. PD-1/PD-L1 Pathway: Current Researches in Cancer. Am J Cancer Res. 2020 Mar 1;10(3):727-742.

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 Summit Therapeutics and the Summit Therapeutics logo are trademarks of Summit Therapeutics Inc. Copyright 2024, Summit Therapeutics Inc. All Rights Reserved. 6Cleveland Clinic. https://my.clevelandclinic.org/health/body/24630-t-cells. Accessed April 2024. 7MD Anderson Cancer Center. https://www.mdanderson.org/cancerwise/what-is-the-tumor-microenvironment-3-things-to-know.h00-159460056.html. Accessed April 2024. 8Shibuya 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.

Summit Therapeutics Q3 2024 Earnings Call October 30, 2024 9:00am ET

Forward Looking Statement 2 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. . Ivonescimab is an investigational therapy not 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 Q3 2024 Earnings Call – October 2024

3 Q3 2024 Highlights 3 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Raised $235M from Leading Biotech Investors Led by well-known biotech institutional and individual investors, including insiders 49% reduction in risk of disease progression over pembrolizumab Benefit demonstrated across PD-L1 low, PD-L1 high, squamous, and non- squamous subgroups Ivonescimab Improves PFS vs. Pembrolizumab in Akeso Ph III Trial in China Expansion of Global HARMONi-3 Phase III Trial: SQ + NSQ Completion of Enrollment in Global HARMONi Phase III Trial Topline data from multi-regional trial expected mid-2025 Fast Track Designation granted by FDA Phase II Data Featured at WCLC & ESMO Encouraging Phase II data presented in CRC, TNBC, HNSCC, and perioperative NSCLC Supports exploration of clinical development outside mNSCLC Upcoming Initiation of HARMONi-7 global Phase III Trial HARMONi-7 expected to initiate early 2025 Study to compare ivonescimab mono vs. pembrolizumab mono in NSCLC PD-L1 high (TPS ≥ 50%) Enrollment expanded to include patients with tumors of non-squamous histology in addition to the currently enrolling patients with squamous tumors

Company Details Focus ONCOLOGY Partnership Akeso Inc. Summit License Territories North America (including United States), South America, Japan, Europe, Middle East, & Africa Chief Executive Officers Bob Duggan Chairman & CEO Dr. Maky Zanganeh CEO & President NASDAQ SMMT Market Cap $16.1B‡ Cash $487M** Employees 150+‡ Offices Miami, FL Menlo Park, CA Oxford, UK …Improve quality of life, increase potential duration of life, and resolve serious medical healthcare needs… MISSION Unmatched high-speed execution, proven track record FOCUSED ON PATIENTS FIRST LEADERSHIP Lead Compound: Ivonescimab Only Phase III PD-1/VEGF Bispecific Antibody in Summit’s License Territories* Summit Therapeutics **As of September 30, 2024; ‡As of October 29, 2024 *There are no known PD-1-based bispecific antibodies approved by the U.S. Food and Drug Administration (“FDA”) or the European Medicines Agency (“EMA”). 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 Q3 2024 Earnings Call – October 2024 4 • Displays unique cooperative binding to each of its intended targets with multifold higher affinity when in the presence of both PD-1 and VEGF1 • Potential to accumulate higher levels of ivonescimab in the TME vs. healthy tissue (higher levels of PD-1 & VEGF expression in the TME)1-3 • The intent of the design, together with shorter half-life of 6 - 7 days1 is to improve upon previously established efficacy thresholds, in addition to side effects and safety profiles associated with these targets4-7 1. Zhong T, et al. AACR-NCI-EORTC International Conference 2023. Poster #B123; 2. Zhao Y. et al., eClinicalMedicine. 2023; 3(62): 102106; 3. Wang L, et al. J Thorac Oncol. 2024;19(3):465-475. 4. Avastin® (bevacizumab). Package insert. Genentech; 2022.; 5. Keytruda® (pembrolizumab). Package insert. Merck; 2024.; 6. Opdivo® (nivolumab). Package insert. Bristol Myers Squibb; 2024.; 7. Libtayo® (cemiplimab-rwlc). Package insert. Regeneron; 2024.

Indication Study Treatment Population Regimen Phase Status NSCLC 2L+ EGFRm + Chemo vs. Chemo Approved 1L PD-L1 Positive Monotherapy vs. pembrolizumab (PD-1) III Primary Analysis 1L Squamous + Chemo vs. tislelizumab (PD-1) + chemo III Ongoing AK112-205 Neoadjuvant/Adjuvant +/- Chemo II Ongoing AK112-208 1L advanced or metastatic + PD-1/CTLA-4 bsAb + chemo II Ongoing Biliary Tract CA TBD 1L + Chemo vs. durvalumab (PD-L1) + chemo III Planned Head & Neck CA TBD 1L PD-L1 Positive + CD47 vs. pembrolizumab (PD-1) III Ongoing Pancreatic CA TBD 1L PDAC + Chemo vs. chemo III Planned Ovarian CA AK112-211 PSOC + Chemo +/- PARP inhibitor II Ongoing Colorectal CA AK112-206 Metastatic MSS CRC +/- CD47, +/- chemo II Ongoing Hepatocellular CA AK112-207 BCLC Stage B or C Monotherapy II Ongoing Ovarian CA AK104-221 Recurrent +/- Chemo, PD-1/CTLA-4 bsAb II Ongoing G/GEJ CA AK117-202 HER2 negative +/- CD47 + chemo II Ongoing Breast CA AK117-203 TNBC + Chemo, CD47 + chemo II Ongoing SCLC AK112-103 Extensive Stage + Chemo I Completed Ivonescimab Global Clinical Trials Ivonescimab More Than 25 Clinical Trials Across 17 Tumor Settings1 1,800+ Patients Treated in Clinical Trials 9 Phase III Trials Completed, Ongoing, or Announced1 1 Approved Oncology Indication in China1 6 Head-to-Head Studies vs. PD-(L)1 9 Dedicated Trials Outside NSCLC1 These ivonescimab clinical trials are being conducted in China and/or Australia and are fully sponsored and managed by Akeso. Indication Study Treatment Population Regimen Phase Status NSCLC 2L+ EGFRm + Chemo vs. chemo III Enrollment Complete 1L + Chemo vs. pembrolizumab (PD-1) + chemo III Ongoing 1L PD-L1 High Monotherapy vs. pembrolizumab (PD-1) III Planned 1. Akeso's 2024 First Half Interim Results (prnewswire.com) Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA) Abbreviations: Abbreviations: 1L=first-line; 2L=second-line; Adeno CA=adenocarcinoma; BCLC=Barcelona clinic liver cancer; BRAC=breast cancer gene; bsAb=bispecific antibody; Chemo=chemotherapy; CD47=cluster of differentiation 47; CTLA-4=cytotoxic T lymphocyte antigen-4; CPS=combined positive score; CRC=colorectal cancer; EGFRm+=epidermal growth factor receptor mutant positives; G/GEJ=gastroesophageal junction; HER2=human epidermal growth factor receptor 2; NSCLC=non-small-cell lung cancer; PARPi=poly(ADP-ribose) polymerase inhibitors; PD-L1=programmed cell death ligand 1; PD- 1=Programmed Cell Death Protein 1; TNBC=triple negative breast cancer; TPS=tumor proportion score; SCLC=Extensive Stage Small Cell Lung Cancer; PDAC=pancreatic ductal adenocarinoma5 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 Approved in China only

Multiple Meetings > Summit & Akeso Partnership Consummated January 2023 NSCLC Phase II Data (poster) Publications, Approval, New Clinical Trials New Akeso Phase III Trials Announced Biliary Tract CA Head & Neck CA Pancreatic CA Shaping the Path to Become a Commercial Entity SITC: Society for Immunotherapy of Cancer; MOA: Mechanism of Action; ASCO: American Society of Clinical Oncology; NSCLC: Non-small Cell Lung Cancer; EORTC: European Organisation for Research and Treatment of Cancer; NCI: National Cancer Institute; AACR: American Association for Cancer Research; IST: Investigator Sponsored Trials CDE: Centre for Drug Evaluation (China) 6 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 Q3 2024 Earnings Call – October 2024 H1 2023 H2 2023 H1 2024 H2 2024 First Patient In First Patient In Last Patient In Announced ISTs Approved Ivonescimab Studies Lung & non-lung Indications Strategic Collaboration MD Anderson Relationships Approval in China Ivonescimab: NSCLC Ivonescimab MOA (Poster) EORTC-NCI-AACR Ivonescimab MOA (Poster) NSCLC Phase II Data (Article) THE LANCET SITC ASCO ASCO JAMA Phase II Data in Non-lung Indications ELCC NSCLC Data Update (poster) NSCLC Phase III Data Non-lung Phase II Data WCLC ESMO NSCLC Clinical Trials Raised $500M Raised $200M Raised $235M FDA ISTs Approved Ivonescimab Studies Lung & non-lung indications Phase III Data also, Biliary Tract Cancer Phase II Poster

Double-blind, randomized Phase III study comparing ivonescimab with pembrolizumab for patients with advanced or metastatic PD-L1-positive NSCLCa Stratification • Clinical stage (IIIB/C vs. IV) • Histology (SQ vs. non-SQ) • PD-L1 Score (high vs. low expressing) HARMONi-2: Study Design Patient Population • Stage IIIB-IV aNSCLC • No prior systemic therapy • No EGFR mutations or ALK rearrangements • ECOG PS 0 or 1 • PD-L1-positive expressing tumors Ivonescimab 20 mg/kg Q3W (N=198) Pembrolizumab 200 mg Q3W (N=200) Treatment until no clinical benefit, unacceptable toxicity or up to 24 months Endpoints Primary: PFS by blind IRRC per RECIST v1.1 Secondary: OS, PFS assessed by INVs, ORR, DoR, TTR and safety Exploratory: QoL a Patients were randomized from November 2022 to August 2023. Data cut off: January 29, 2024. Abbreviations: aNSCLC, advanced non-small cell lung cancer; EGFR, epidermal growth factor receptor; ALK, anaplastic lymphoma kinase; ECOG PS, Eastern Cooperative Oncology Group performance score; PD-L1, programmed death ligand 1; TPS, tumor proportion score; R, randomization; SQ, squamous cell carcinoma; Q3W, every three weeks; PFS, progression-free survival; IRRC, independent radiology review committee; OS, overall survival; INV, investigator; ORR, overall response rate; DoR, duration of response; TTR, time to response; QoL, quality of life. 2024 World Conference on Lung Cancer Presidential Symposium, 9/8/24, San Diego, CA Caicun Zhou | HARMONi-2 Akeso Sponsored Study 7 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 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. 1:1 Ra nd om iza tio n N=398

HARMONi-2: Primary Endpoint: PFS per IRRC Abbreviations: mPFS, median progression-free survival; IRRC, independent radiology review committee; mo, month; NE, not estimable; HR: hazard ratio; CI, confidence interval. Ivonescimab (n = 198) Pembrolizumab (n = 200) mPFS, mos (95% CI) 11.14 (7.33, NE) 5.82 (5.03, 8.21) Stratified HR (95% CI) 0.51 (0.38, 0.69) p-value <0.0001 Ivonescimab is the first compound to demonstrate a statistically significant improvement in PFS vs. pembrolizumab with HR = 0.51, and 5.3 months improvement in mPFS. 2024 World Conference on Lung Cancer Presidential Symposium, 9/8/24, San Diego, CA Caicun Zhou | HARMONi-28 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 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. 9-mo: 40% (32, 48) 9-mo: 56% (47, 64) Median Follow-up: 8.67 months PF S (% ) Time (months) Number at risk (Events) Ivonescimab Pembrolizumab Censor Ivonescimab Pembrolizumab

HARMONi-2: Key PFS Subgroup Analyses PD-L1 High (TPS ≥50%)PD-L1 Low (TPS 1-49%) Ivonescimab showed meaningful improvement in PFS vs. pembrolizumab in patients with both low and high PD-L1, with squamous or non-squamous advanced NSCLC. Stratified HR (95% CI) 0.54 (0.37, 0.79) Stratified HR (95% CI) 0.46 (0.28, 0.75) Stratified HR (95% CI) 0.48 (0.31, 0.74) Stratified HR (95% CI) 0.54 (0.36, 0.82) Non-SquamousSquamous NSCLC Histology PD-L1 Expression 2024 World Conference on Lung Cancer Presidential Symposium, 9/8/24, San Diego, CA Caicun Zhou | HARMONi-29 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 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.

a Patients who received ≥1 dose of study treatment. Abbreviations: AEs, adverse events; TRAEs, treatment-related adverse events; SQ, squamous cell carcinoma. TRAEs HARMONi-2: Safety Summary Safety Summary, n (%) Ivonescimab (n = 90a) Pembrolizumab (n = 91a) TRAEs (all grades) 77 (85.6) 73 (80.2) Grade≥3 20 (22.2) 17 (18.7) Serious TRAEs 17 (18.9) 17 (18.7) Leading to discontinuation 2 (2.2) 3 (3.3) Leading to death 0 1 (1.1) TRAEs in SQ Subgroup Safety Summary, n (%) Ivonescimab (n = 197a) Pembrolizumab (n = 199a) TRAEs (all grades) 177 (89.8) 163 (81.9) Grade≥3 58 (29.4) 31 (15.6) Serious TRAEs 41 (20.8) 32 (16.1) Leading to discontinuation 3 (1.5) 6 (3.0) Leading to death 1 (0.5) 2 (1.0) Most Common TRAEs (incidence ≥10%) 2024 World Conference on Lung Cancer Presidential Symposium, 9/8/24, San Diego, CA Caicun Zhou | HARMONi-210 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 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. The differences in AEs were predominantly proteinuria, hypertension, and laboratory abnormalities. Ivonescimab showed a manageable safety profile, which was consistent with previous studies. Ivonescimab also demonstrated a tolerable safety profile in SQ patients.

HARMONi-2: irAEs and Possible VEGF-Related AEs • All VEGF-related AEs were grades 1-3 in both arms. • Grade 3 haemorrhage was observed in two patients with non-SQ and was not reported in SQ patients in the ivonescimab arm. irAEs Safety Summary, n (%) Ivonescimab (n = 197a) Pembrolizumab (n = 199a) Possible VEGF-Related AEs (all grades) 94 (47.7) 42 (21.1) Grade≥3 20 (10.2) 2 (1.0) Possible VEGF-Related AEs Safety Summary, n (%) Ivonescimab (n = 197a) Pembrolizumab (n = 199a) irAEs (all grades) 59 (29.9) 56 (28.1) Grade≥3 14 (7.1) 16 (8.0) Serious irAEs 11 (5.6) 22 (11.1) Leading to discontinuation 0 5 (2.5) Leading to death 0 0 Safety Summary by Classification, n (%) Ivonescimab (n = 197a) Pembrolizumab (n = 199a) All Grade Grade≥3 All Grade Grade≥3 Proteinuria 62 (31.5) 6 (3.1) 20 (10.1) 0 Hypertension 31 (15.7) 10 (5.1) 5 (2.5) 1 (0.5) Haemorrhage 29 (14.7) 2 (1.0) 22 (11.1) 1 (0.5) Arterial thromboembolism 2 (1.0) 2 (1.0) 1 (0.5) 0 Venous thromboembolism 0 0 1 (0.5) 0 a Patients who received ≥1 dose of study treatment. Abbreviations: VEGF, vascular endothelial growth factor; irAEs, immune- related AEs; AEs, adverse events; SQ, squamous cell carcinoma. 2024 World Conference on Lung Cancer Presidential Symposium, 9/8/24, San Diego, CA Caicun Zhou | HARMONi-211 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 Ivonescimab is an investigational therapy not approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Data generated and analyzed by Akeso. Ivonescimab exhibited similar irAEs to that of pembrolizumab.

HARMONi-7: Phase III Study in 1L Metastatic NSCLC with PD-L1 High (NCT not yet assigned) • Untreated squamous or non- squamous metastatic NSCLC with PD-L1 high expression • ECOG 0 or 1 Stratification factors to include histology (squamous vs non- squamous) Treatment until: • Intolerable toxicity, or • Disease progression, or • 24 months of treatment Safety and Survival Follow up Group B Pembrolizumab 200 mg Q3W R 1:1 (N=780) Group A Ivonescimab 20 mg/kg Q3W Study Endpoints Primary endpoints: PFS, OS Secondary endpoints: ORR, safety and tolerability Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). 12 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024

HARMONi-3: Intended Amended Study Design Ivonescimab + Carboplatin + Paclitaxel (or nab-paclitaxel) + Q3W x 4 cycles Pembrolizumab + Carboplatin + Paclitaxel (or nab-paclitaxel) Q3W x 4 cycles Key Inclusion § First line Stage IV squamous and non- squamous NSCLC Key Exclusion § Known actionable mutations for which first line approved agents are available § Symptomatic CNS metastases § Major blood vessel or organ invasion § Active autoimmune disease Treatment Until: § Disease progression § Unacceptable toxicity § Withdrawal of consent/death § Initiation of a new anti-tumor therapy § Complete 24 months of treatment Primary • OS, PFS by Investigator Secondary • ORR, DCR, DOR , safety, PK, immunogenicity Ivonescimab + Carboplatin + Pemetrexed Q3W x 4 cycles Pembrolizumab + Carboplatin + Pemetrexed, Q3W x 4 cycles 1:1 Ra nd om iza tio n Squamous Non-Squamous OR Squamous: Pembrolizumab Squamous: Ivonescimab Non-Squamous: Pembrolizumab + Pemetrexed Non-Squamous: Ivonescimab + Pemetrexed Maintenance n = ~1080 Safety and Survival Follow -up 13 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 Endpoints Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Stratification Factors Include Histology (Squamous vs. Non-Squamous)

AK112-201: Study Design • ORR according to RECIST v1.1 assessed by the investigator • Safety Primary Endpoints Cohort 1 1L without EGFR/ALK alteration Cohort 2 EGFR+ adv Progressed after EGFR-TKI Cohort 3 Progressed after platinum-doublet with PD-1 Ivonescimab + pemetrexed + carboplatin (non-squamous) or Ivonescimab + paclitaxel + carboplatin (squamous) Ivonescimab + pemetrexed + carboplatin Ivonescimab + docetaxel A Trial of AK112 (PD-1/VEGF Bispecific) in Combination with Chemotherapy in Patients with NSCLC. ClinicalTrials.gov identifier: NCT04736823. https://classic.clinicaltrials.gov/ct2/show/NCT04736823. (Accessed 2024, May 17); Zhao Y, et al. EClinicalMedicine. 2023;62:102106; 3. Zhang L, et al., ELCC 2024 poster #FPN68P Abbreviations: ALK=anaplastic lymphoma kinase; EGFR=epidermal growth factor reception; NSCLC=non-small Cell Lung Cancer; ORR=objective response rate; PD-1=programmed Cell Death Protein 1; TKI=tyrosine kinase inhibitor Phase 2, multi-center, open-label study in patients with advanced NSCLC in China (NCT04736823) Akeso-Sponsored Study 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. 14 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024

Med OS, mo (95% CI) Squamous NSCLC (n=63) Not Reached (22.5-NE) Non-Squamous NSCLC (n=72) Not Reached (17.5-NE) AK112-201: Efficacy Data Cohort 1 - Ivonescimab plus Chemo in NSCLC Without EGFR/ALK Alteration Abbreviations: CI=confidence interval; KM=Kaplan-Meier; mo=months; NE=non-estimable; NR=not reached; OS=overall survival 1. Zhang L, et al., ELCC 2024 poster #FPN68P Med PFS, mo (95% CI) Squamous NSCLC (n=63) 11.1 (9.5-16.3) Non-Squamous NSCLC (n=72) 13.3 (8.3-16.4) (N=135)1 Median duration of follow up: 22.1 months Data cutoff: October 10, 2023 Median duration of follow up: 21.3 months Data cutoff: October 10, 2023 Pr ob ab ili ty o f O ve ra ll Su rv iv al Pr ob ab ili ty o f P ro gr es si on F re e Su rv iv al 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.15 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024

Summary of Safety, n (%) Squamous (n=63) Non-Squamous (n=72) Grade ≥3 TRAE 28 (44.4) 18 (25.0) TRSAE 18 (28.6) 14 (19.4) TRAE leading to ivonescimab discontinuation 7 (11.1) 2 (2.8) TRAE leading to death 0 3 (4.2) Data cutoff: October 10, 2023 AK112-201: Safety Data Cohort 1 - Ivonescimab plus Chemo in NSCLC Without EGFR/ALK Alteration Abbreviations: TRAE: Treatment related adverse event; TRSAE: Treatment related serious adverse event Zhang L, et al., ELCC 2024 poster #FPN68P 16 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 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.

Phase II Study Designs: CRC, TNBC, HNSCC, Early-Stage NSCLC Akeso-Sponsored Phase II Studies Conducted in China 17 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 Ivonescimab is an investigational therapy not approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Data generated and analyzed by Akeso. Perioperative Resectable NSCLC • Open-label, multi-center phase II study, • Patients diagnosed with resectable stage II, IIIA or IIIB NSCLC were enrolled into two cohorts • Patients received neoadjuvant ivonescimab (20 mg/kg) monotherapy (cohort 1), or ivonescimab (20 mg/kg or 30 mg/kg) plus chemotherapy (cohort 2), followed by surgery and adjuvant ivonescimab • Primary endpoints: safety and MPR 1L Triple Negative Advanced Breast Cancer (TNBC) • Open-label, multi-center phase II study in patients with locally advanced unresectable or metastatic TNBC • Patients received ivonescimab and chemotherapy or chemotherapy • Primary endpoints: ORR by RECIST v1.1 and safety • Secondary endpoints: DoR, DCR, PFS, and OS 1L MSS Metastatic Colorectal Cancer (mCRC) • Open-label, multi-center, phase II randomized study • Untreated mCRC patients randomized 1:1 to receive FOLFOXIRI + ivonescimab (group A) or FOLFOXIRI + ivonescimab + ligufalimab (CD47) (group B), followed by maintenance with 5-fluoruracil + ivonescimab with (group B) or without ligufalimab (group A) • Primary endpoints: ORR by RECIST v1.1 and safety 1L PD-L1-Positive Head-and-Neck SCC (R/M HNSCC) • Open-label, multi-center phase II study • R/M HNSCC patients with PD-L1 positive (CPS≥1), including oropharynx, hypopharynx, larynx or oral cavity cancer • Patients received ivonescimab monotherapy or in combination with ligufalimab (CD47) • Primary endpoint: ORR per RECIST v1.1 assessed by investigator

Promising Phase II Data: CRC, TNBC, HNSCC, NSCLC Perioperative Resectable NSCLC Ivonescimab (n=11) Ivo + Chemo (n=49) pCR (n = 10; n = 39, respectively) 30.0% 43.6% MPR (n = 10; n = 39, respectively) 60.0% 71.8% 12-month EFS 81.8% 80.3% No TRAEs led to cancelled / delayed surgery or wound healing complications. 1L MSS mCRC Ivo + Chemo (n = 22) Ivo + CD47 + Chemo (n = 18) ORR (n = 22; n = 17, respectively) 81.8% 88.2% DCR (n = 22; n = 17, respectively) 100% 100% 9-month PFS Rate 81.4% 86.2% TRAE-Led Discontinuations 0 1 1L PD-L1-positive R/M HNSCC Ivonescimab (n =10) Ivo + CD47 (n=20) ORR 30.0% 60.0% DCR 80.0% 90.0% Median PFS 5.0 mos 7.1 mos TRAE-Led Discontinuations 0 1L TNBC Ivo + Chemo CPS <10% (n=24) Ivo + Chemo CPS >10% (n=6) ORR (n = 23; n = 6, respectively) 69.6% 83.3% DCR (n = 23; n = 6, respectively) 100% 100% 6-month PFS Rate 71.2% 80.0% TRAE-Led Discontinuations 0 18 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 2024 IASLC World Conference on Lung Cancer European Society of Medical Oncology Annual Meeting 2024 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. Akeso-Sponsored Phase II Studies Conducted in China

19 Q3 2024 Highlights 19 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024 Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China’s National Medical Products Administration (NMPA). Raised $235M from Leading Biotech Investors Led by well-known biotech institutional and individual investors, including insiders 49% reduction in risk of disease progression over pembrolizumab Benefit demonstrated across PD-L1 low, PD-L1 high, squamous, and non- squamous subgroups Ivonescimab Improves PFS vs. Pembrolizumab in Akeso Ph III Trial in China Expansion of Global HARMONi-3 Phase III Trial: SQ + NSQ Completion of Enrollment in Global HARMONi Phase III Trial Topline data from multi-regional trial expected mid-2025 Fast Track Designation granted by FDA Phase II Data Featured at WCLC & ESMO Encouraging Phase II data presented in CRC, TNBC, HNSCC, and perioperative NSCLC Supports exploration of clinical development outside mNSCLC Upcoming Initiation of HARMONi-7 global Phase III Trial HARMONi-7 expected to initiate early 2025 Study to compare ivonescimab mono vs. pembrolizumab mono in NSCLC PD-L1 high (TPS ≥ 50%) Enrollment expanded to include patients with tumors of non-squamous histology in addition to the currently enrolling patients with squamous tumors

Financial Summary Q3’24 vs. Q2’24 Key Items as of September 30, 2024: • Closed private financing of $235M • Cash, cash equivalents, and short-term investments: $487M • Total shares outstanding: 737M (1) Excludes stock-based compensation (2) Excludes a one-time charge associated with the Company's in-licensing of ivonescimab from Akeso. Refer to the next slides for reconciliations between Generally Accepted Accounting Principles (GAAP) and Non-GAAP financial measures. 20 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024

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. Note 2: Acquired in-process research and development represents a one-time charge associated with the Company's in-licensing of ivonescimab from Akeso.21 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024

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. Note 2: Acquired in-process research and development represents a one-time charge associated with the Company's in-licensing of ivonescimab from Akeso. 22 Summit Confidential & Proprietary Information - Do Not Copy or Distribute Presentation Summit Therapeutics Q3 2024 Earnings Call – October 2024

Summit Therapeutics Q3 2024 Earnings Call October 30, 2024 9:00am ET

Cover	Oct. 30, 2024
Cover [Abstract]
Document Type	8-K
Document Period End Date	Oct. 30, 2024
Entity Registrant Name	Summit Therapeutics Inc.
Entity Incorporation, State or Country Code	DE
Entity File Number	001-36866
Entity Tax Identification Number	37-1979717
Entity Address, Address Line One	601 Brickell Key Drive, Suite 1000
Entity Address, City or Town	Miami
Entity Address, State or Province	FL
Entity Address, Postal Zip Code	33131
City Area Code	(305)
Local Phone Number	203-2034
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Title of 12(b) Security	Common stock, $0.01 par value per share
Trading Symbol	SMMT
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	false
Entity Central Index Key	0001599298
Amendment Flag	false