SMMT · Summit Therapeutics Inc.

// // Consistent Overall Survival Observed in Western, Asian Patients in Updated Analysis from Phase III HARMONi Study in EGFRm NSCLC Post-TKI Setting for Ivonescimab Plus Chemotherapy vs. Chemotherapy Ivonescimab Plus Chemotherapy Achieves Statistically Significant and Clinically Meaningful Overall Survival Benefit in 1L Squamous NSCLC HARMONi-6 Trial Conducted in China, the First Phase III Head-to-Head Clinical Study to Demonstrate Superiority over an Anti-PD-(L)1 Antibody-Containing Regimen HARMONi-3 Global Phase III 1L NSCLC Study: Squamous Cohort Final PFS Analysis Events Expected to Be Reached in Second Half of 2026 with Interim OS Analyses Planned; Non-Squamous Cohort PFS Events Expected to Be Reached in the First Half of 2027 Summit Closes Second Quarter with $690.7 Million in Cash and Investments MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today reported its financial results for the second quarter and six months ended June 30, 2026 and provided an update on clinical and operational progress. “The clinical momentum of ivonescimab continues to build, with two recent key data readouts that significantly bolster our development progress. At ASCO, the landmark HARMONi-6 results established the first head-to-head Phase III study in any tumor type to demonstrate a meaningful overall survival advantage over anti-PD-1 inhibitors in combination with chemotherapy, representing an important milestone for cancer patients and for the broader immuno-oncology field,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit. “This was followed by updated overall survival data from the HARMONi trial, in which western patients replicated the survival benefit seen in Asian patients and further reinforces our confidence in the regional consistency of the efficacy results of ivonescimab.” “These new data continue to demonstrate the differentiated profile of ivonescimab,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit. “In HARMONi-6, we saw an outcome that underscores the potential impact of our bispecific PD-1 / VEGF program. Equally important, the updated HARMONi overall survival analysis provided additional evidence of consistency of efficacy outcomes across patient populations. We also presented encouraging Phase II colorectal cancer data at ASCO that adds to the growing body of evidence supporting the potential of ivonescimab as a differentiated PD-1 / VEGF bispecific antibody across tumor types. We believe these results meaningfully strengthen the overall body of evidence supporting ivonescimab and provide important validation as we advance our global development program across multiple solid tumors.” Clinical & Operational Updates Clinical and 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: Summit in-licensed ivonescimab from Akeso Inc. (Akeso, HKEX Code: 9926.HK) in January 2023. In total, over 4,000 patients have been treated with ivonescimab in clinical studies globally, and over 70,000 patients have been treated in the commercial setting with ivonescimab in China, as noted and updated by Akeso. Summit has exclusive rights to develop and commercialize ivonescimab in North America, South America, Europe, the Middle East, Africa, and Japan, while Akeso retains development and commercialization rights for remaining territories, including China. Summit is developing ivonescimab in non-small cell lung cancer (NSCLC) and colorectal cancer (CRC), specifically conducting multiregional 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 were previously treated with a third-

// // Data Expected to Be Generated by Mid-2027 HAYWARD, Calif. & MIAMI--(BUSINESS WIRE)-- Arcus Biosciences, Inc. (NYSE: RCUS), a clinical-stage, global biopharmaceutical company focused on developing differentiated molecules and combination therapies for people with cancer and inflammatory and autoimmune diseases, and Summit Therapeutics Inc. (Nasdaq: SMMT), a biopharmaceutical company focused on patient-friendly oncology therapies intended to improve quality of life, increase potential duration of life, and resolve serious unmet medical needs, today announced a clinical trial collaboration to evaluate the safety and efficacy of Arcus’s casdatifan, an investigational hypoxia-inducible factor 2-alpha (HIF-2α) inhibitor, in combination with Summit’s ivonescimab, an investigational PD-1 / VEGF bispecific antibody, in clear cell renal cell carcinoma (ccRCC), including first-line metastatic disease, the most common form of kidney cancer. “Combining casdatifan, a hard-hitting HIF-2α inhibitor, with ivonescimab, the most advanced and well-studied anti-PD-1 / VEGF bispecific, presents a compelling opportunity to create a well-tolerated and TKI-sparing combination that has the potential to prolong survival,” said Terry Rosen, Ph.D., Chief Executive Officer of Arcus. “Our development strategy is to establish casdatifan as a backbone therapy so that every patient has the opportunity to benefit from casdatifan across each line of therapy, and this collaboration enables the evaluation of a highly innovative regimen with strong scientific and clinical rationale to be an important first-line treatment for kidney cancer.” The clinical trial collaboration will evaluate casdatifan in combination with ivonescimab in a new cohort to be added to ARC-20, Arcus’s platform study, evaluating casdatifan alone or in combination with other potential treatment options across multiple cohorts in metastatic ccRCC. Under the terms of the agreement, Summit will supply ivonescimab and Arcus will conduct and sponsor the combination study. Both companies will contribute to the cost of the study, and each company will retain development and commercial rights to their respective molecules. Initial data from this clinical trial collaboration is expected to be generated by mid-2027. “Ivonescimab’s novel mechanism of action targeting both the PD-1 axis and VEGF pathway is particularly compelling in renal cell carcinoma, where both pathways are known to play an important role in disease progression,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “We are excited to get this work underway with Arcus to evaluate whether the combination of ivonescimab and casdatifan can translate into improved and more durable outcomes for patients. Despite recent advances, kidney cancer remains a disease area with stark stage-dependent survival where only a small proportion of patients survive beyond five years, highlighting the ongoing unmet need in this tumor setting.” About Kidney Cancer According to the American Cancer Society, kidney cancer is among the top 10 most commonly diagnosed forms of cancer among both men and women in the U.S., and an estimated 80,450 Americans will be diagnosed with kidney cancer in 2026. 1 ccRCC is the most common type of kidney cancer in adults. 2 If detected in its early stages, the five-year survival rate for kidney cancer is high; for patients with advanced or late-stage metastatic kidney cancer, however, the five-year survival rate is only 19%. 3 For metastatic kidney cancer, targeted drug therapies are one of the main treatment options. 4 About Casdatifan (AB521) Casdatifan is a small-molecule inhibitor of hypoxia-inducible factor 2-alpha (HIF-2α), a master switch that turns on hundreds of genes in response to low oxygen levels. In a majority of people with the most common form of kidney cancer (clear cell renal cell carcinoma), genetic anomalies result in the dysregulation of this master switch and trans

// // Western Patients Achieved OS HR of 0.76, Consistent with Asian Patients in this Global Phase III Study MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) today announced results of an updated overall survival (OS) analysis from the global Phase III HARMONi clinical trial featuring the novel, potential first-in-class investigational bispecific antibody ivonescimab. Ivonescimab plus platinum-doublet chemotherapy in this trial continues to show a positive OS trend and a consistent efficacy and safety profile in Asian and western patients when compared to chemotherapy alone. The HARMONi study is evaluating ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with endothelial growth factor receptor (EGFR)-mutated, locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who were previously treated with a third-generation EGFR tyrosine kinase inhibitor (TKI). The study demonstrated a statistically significant benefit in the primary analysis for progression-free survival (PFS), one of the study’s two primary endpoints along with OS. Summit’s Biologics License Application (BLA) with the U.S. Food and Drug Administration (FDA) is based on the results from the HARMONi trial and has a Prescription Drug User Fee Act (PDUFA) goal action date of November 14, 2026. In April 2025, the primary OS analysis was performed, whereby ivonescimab in combination with chemotherapy showed a positive trend without achieving a statistically significant benefit with a hazard ratio of 0.79 (95% CI: 0.62 – 1.01; p=0.057). Median OS was 16.8 months for those patients administered ivonescimab plus chemotherapy vs. 14.0 months for those receiving placebo plus chemotherapy. At the time of the primary analysis, median follow-up time for western patients was 9.2 months and less than the median OS at the time of the primary analysis. In September 2025, an additional analysis was performed, whereby the western patients were followed to increase their time on study (Asian patients were included and locked at the time of the primary analysis at a median follow-up time of 32.7 months). This analysis included longer-term follow-up of western patients of 13.7 months. A hazard ratio of 0.78 (95% CI: 0.62 – 0.98; nominal p=0.0332) was observed, consistent with the primary analysis. Median OS remained the same in both arms from the primary analysis. An additional analysis was performed with a data cut-off date in June 2026, whereby most western patients have now discontinued treatment or completed two years of treatment. The median follow-up time for western patients now is 23.2 months. The cutoff date for Asian patients was consistent with the prior analysis with a median follow-up time of 32.7 months. A hazard ratio of 0.76 was observed in both the full intention-to-treat population and the subgroup of western patients. More detailed data from this analysis are intended to be presented at an upcoming medical meeting. These results have been made available to the FDA. Global Overall Survival Analyses at Each Data Cut-Off DCO: Apr 2025 (Primary Analysis) DCO: Sept 2025 DCO: June 2026* Ivonescimab + Chemo Placebo + Chemo Ivonescimab + Chemo Placebo + Chemo Ivonescimab + Chemo Placebo + Chemo (n=219) (n=219) (n=219) (n=219) (n=219) (n=219) Hazard Ratio, ITT 0.79 0.78 0.76 DCO = data cut-off; ITT = intention-to-treat population; mos = months; chemo = chemotherapy *Note: Additional information, including median OS, confidence intervals for hazard ratios, etc., are intended to be presented at an upcoming medical conference The hazard ratios for the subgroup of western patients improved from the analysis in April 2025 to the September 2025 and June 2026 analyses with longer-term follow-up of western patients. With longer follow-up, results of western patients are now consistent in terms of the magnitude of OS benefit with those patients enrolled in Asia, who had a longer follow-up at the time of the pri

// // Conference Call to Be Held at 4:30 p.m. EDT MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) will host a conference call to announce its second quarter 2026 financial results and provide an update on operational progress on Thursday, July 23, 2026. The call is scheduled to take place at 4:30 p.m. EDT. The live and archived webcast can be accessed through the Investor Information section of the company’s website, www.smmttx.com . About Summit Therapeutics Inc. 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 the company’s shares are listed on the Nasdaq Global Market (symbol "SMMT"). Summit is headquartered in Miami, Florida, with additional offices in Palo Alto, California, Princeton, New Jersey, Dublin, Ireland, and Oxford, UK. For more information, please visit https://www.smmttx.com and follow Summit on X @SMMT_TX. 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. and other collaborations, 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, the expected timing of BLA submissions or FDA decisions, potential acquisitions, statements about the previously disclosed At-The-Market equity offering program (“ATM Program”), the expected proceeds and uses thereof, the Company’s estimates regarding stock-based compensation, 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 effects of geopolitical developments, domestic and foreign trade policies, and monetary policies, 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 a

// // MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced it has signed an agreement with Toronto-based Biossil, Inc. for the sale of ridinilazole, an investigational Phase III precision antibiotic owned by Summit. Biossil is an artificial intelligence (AI)-native biopharma company focused on advancing late-stage programs in life-threatening indications with urgent unmet medical needs. Previously, ridinilazole was evaluated in Summit’s Phase III Ri-CoDIFy study for the treatment of patients suffering from C. difficile infection ( C. diff. infection or CDI), an area of high unmet need. The study showed that ridinilazole resulted in a higher observed Sustained Clinical Response (SCR) rate than vancomycin but did not meet the study’s primary endpoint for superiority within the established time boundaries. SCR is defined as Clinical Response of the treated episode of CDI and no recurrence of the infection through 30 days after the end of treatment. These results were announced by Summit in December 2021 and subsequently published in the journal Clinical Infectious Diseases. 1 Ri-CoDIFy, as well as earlier-stage clinical studies of ridinilazole, demonstrated its ability to spare the gut microbiome compared to vancomycin, the standard of care in C. difficile infection, which is believed to impact recurrence of the disease. The gut microbiome and its homeostasis have been linked to overall quality of human health across several recent studies. “Ridinilazole has long represented a scientifically differentiated approach to addressing Clostridioides difficile infection, a serious disease that continues to place a substantial burden on patients, caregivers, and healthcare systems,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit. “We believe Biossil’s AI-native development capabilities and focus on urgent unmet medical needs make them well positioned to advance this program, while allowing Summit to continue prioritizing our core oncology strategy and the development of ivonescimab. Summit is pleased that Biossil is planning to continue clinical development of ridinilazole to unlock its potential. The exploratory data in previous clinical trials, which require further study, demonstrated numerical differences favoring ridinilazole versus vancomycin, including microbiome preservation, lower recurrence rates, reduced toxin production, dosing convenience, and tolerance.” Under the terms of the agreement, Summit will receive $500,000 upfront and up to $104.5 million in regulatory and commercial milestones, plus tiered royalties on net sales. “Introduction of novel, microbiome-sparing antibiotics has lagged the growing global need,” said Alexander Mosa, MD, PhD, CSO and Chair of Biossil. “Recurrent C. difficile infection, selection of antibiotic-resistant genes, and gut dysbiosis are common, burdensome, and in need of new approaches. We thank Summit for entrusting us with continued development of ridinilazole, and we will advance this program with urgency and focus.” The use of ridinilazole is not approved and its safety and efficacy have not been evaluated by regulatory authorities, including the United States Food and Drug Administration (FDA). About C. Difficile Infection Clostridioides difficile , or C. difficile , infection (CDI) is a bacterial infection of the colon that produces toxins causing inflammation of the colon, severe watery diarrhea, painful abdominal cramping, nausea, fever, and dehydration. CDI can also result in more serious disease complications, including bowel perforation, sepsis, and death. CDI is a contagious infectious disease that represents a serious healthcare issue in hospitals, long-term care facilities, and the wider community. According to the Peggy Lillis Foundation, C. difficile causes nearly 500,000 infections in the United States each year and contributes to more than 29,000 deaths annually. 2 The foundation also describes C. difficile as the most commo

// // MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) (“Summit,” “we,” or the “Company”) today announced that it has commenced an underwritten public offering of $500.0 million of shares of its common stock. All of the shares in the proposed offering are being offered by Summit. In addition, Summit intends to grant the underwriters a 30-day option to purchase up to an additional $75.0 million of shares of its common stock at the public offering price, less underwriting discounts and commissions. The proposed offering is subject to market and other conditions, and there can be no assurance as to whether or when the offering may be completed, or as to the actual size or terms of the offering. Summit intends to use the net proceeds from the proposed offering, together with its existing cash, cash equivalents, to fund the research and development of its lead product candidate, ivonescimab, and for working capital and other general corporate purposes. J.P. Morgan, Goldman Sachs & Co. LLC and Citigroup are acting as joint book-running managers for the proposed offering. The securities described above are being offered by Summit pursuant to a shelf registration statement on Form S-3, including a base prospectus, that was previously filed with the Securities and Exchange Commission (SEC) and which became automatically effective on June 9, 2026. A preliminary prospectus supplement and accompanying base prospectus relating to and describing the terms of the proposed offering will be filed with the SEC and will be available on the SEC’s website at www.sec.gov . Copies of the preliminary prospectus supplement and accompanying base prospectus may also be obtained, when available, from: J.P. Morgan Securities LLC, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, or by email at [email protected] and [email protected] ; Goldman Sachs & Co. LLC, Attention: Prospectus Department, 200 West Street, New York, NY 10282, by telephone at (866) 471-2526, or by email at [email protected] ; or Citigroup, c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, NY 11717, or by telephone at (800) 831-9146. This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation, or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction. 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 Palo Alto, California, Princeton, New Jersey, Dublin, Ireland, and Oxford, UK. For more information, please visit <a href="https:/

// // MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced that it will participate in and present at the 47 th Annual Goldman Sachs Global Healthcare Conference in Miami, Florida on Monday, June 8, 2026. Members of the Summit management team will participate in a fireside chat presentation at 10:00 AM ET, providing a corporate overview and update on recent progress, including the development of its innovative investigational bispecific antibody, ivonescimab. The presentation will be available live through the company’s website: www.smmttx.com . An archived version of the presentation will be available on the website following the presentation. About Summit Therapeutics Inc. 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 the company’s shares are listed on the Nasdaq Global Market (symbol "SMMT"). Summit is headquartered in Miami, Florida, with additional offices in Palo Alto, California, Princeton, New Jersey, Dublin, Ireland, and Oxford, UK. For more information, please visit https://www.smmttx.com and follow Summit on X @SMMT_TX . 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. and other collaborations, 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, the expected timing of BLA submissions or FDA decisions, potential acquisitions, statements about the previously disclosed At-The-Market equity offering program (“ATM Program”), the expected proceeds and uses thereof, the Company’s estimates regarding stock-based compensation, 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

// // Ivonescimab Plus Chemotherapy Reduced the Risk of Death by 34% Compared to Tislelizumab Plus Chemotherapy; Hazard Ratio 0.66 First Regimen to Achieve a Statistically Significant and Clinically Meaningful Overall Survival Benefit over an anti-PD-(L)1 Antibody Combined with Chemotherapy in a Phase III Clinical Trial in 1L NSCLC Tolerable Safety Profile Consistent with Prior Clinical Trial Results Simultaneous Publication of Latest Ivonescimab HARMONi-6 Results in The Lancet Summit Conference Call to Be Held at 7:00 a.m. ET on Monday, June 1, 2026 MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced positive overall survival (OS) results from the Phase III HARMONi-6 trial, conducted in China and sponsored by Summit’s partner Akeso, Inc. (HKEX Code: 9926.HK), will be presented today as part of the Plenary Session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The presentation is entitled “ Ivonescimab plus chemotherapy versus tislelizumab plus chemotherapy in previously untreated advanced squamous non-small cell lung cancer: Overall survival results of the phase 3 HARMONi-6 trial .” HARMONi-6 is evaluating ivonescimab in combination with platinum-based chemotherapy compared to tislelizumab, a PD-1 inhibitor, in combination with platinum-based chemotherapy in patients with locally advanced or metastatic squamous non-small cell lung cancer (NSCLC) irrespective of PD-L1 expression. HARMONi-6 is a single region, multi-center, Phase III study conducted in China and sponsored by Akeso, with all relevant data exclusively generated, managed, and analyzed by Akeso. The trial’s primary endpoint is progression-free survival (PFS), and OS is a key secondary endpoint. The trial results will be presented by Dr. Shun Lu, MD, PhD, Chief of Shanghai Lung Cancer Center at Shanghai Chest Hospital, Professor of Medicine at Shanghai Jiaotong University, and associate editor for the Journal of Thoracic Oncology . In major markets globally, first-line therapy for patients with advanced NSCLC without driver mutations is most commonly a PD-1 inhibitor plus platinum-based chemotherapy. Prior to HARMONi-6, there were no known Phase III clinical trials in advanced NSCLC which have shown a statistically significant and clinically meaningful improvement in OS when compared to PD-(L)1 inhibitor therapy in combination with chemotherapy in a head-to-head setting. Examples of PD-(L)1 inhibitors include pembrolizumab, nivolumab, tislelizumab, and atezolizumab. Clinically Meaningful Efficacy In the HARMONi-6 planned inte

// // Promising Data Further Support Continued Expansion of Ivonescimab Clinical Development in mCRC Overall Study Population Achieved ORR of 70.8% and DCR of 100.0%; Responses Consistent Across Ivonescimab Dose Levels Combined with Chemotherapy Acceptable and Manageable Safety Profile for Ivonescimab Regimen; No New Safety Signals Observed MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today presented new results from the AK112-206 trial (NCT05382442), a global, open-label, multicenter Phase II study in first-line metastatic colorectal cancer (mCRC) co-sponsored by Summit and Akeso, featuring the novel, potential first-in-class investigational bispecific antibody ivonescimab. The data were presented today at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago. The presentation, entitled “ Ivonescimab with Oxaliplatin + Fluorouracil + Leucovorin Calcium for Patients with Unresectable Metastatic Colorectal Cancer: A Phase 2 Study,” detailed interim results of the multiregional extension portion of the study evaluating ivonescimab combined with mFOLFOX6 chemotherapy in patients with unresectable microsatellite stable (MSS) mCRC who were previously untreated for metastatic disease. Patients (n=49) were randomized (1:1) to receive ivonescimab (10 or 20 mg/kg; n=24, n=25, respectively) plus mFOLFOX6 once every two weeks. The data cut-off for this analysis was March 31, 2026 (10 or 20 mg/kg median follow-up: 9.9 months, 9.8 months, respectively). In this U.S.- and China-based Phase II cohort of treatment-naïve patients with mCRC, patients receiving ivonescimab in combination with standard-of-care doublet chemotherapy mFOLFOX6 demonstrated an objective response rate (ORR) of 70.8% across both arms in evaluable patients (n=48). This result is encouraging compared to historical performance of standard-of-care regimens combining bevacizumab with FOLFOX chemotherapy from prior studies. Treatment responses in the ivonescimab 20 mg/kg arm were more durable than in the ivonescimab 10 mg/kg arm, with a duration of response landmark estimate at 9 months of 79.1% vs. 41.5%, respectively. While progression-free survival (PFS) analysis is still immature in this study, the landmark 9-month PFS rate was 76.1% for those patients receiving 20 mg/kg of ivonescimab. The safety profile of ivonescimab combined with chemotherapy in this study is comparable to rates observed in historical studies with chemotherapy and anti-VEGF antibodies. In total including both arms, 20.4% of patients experienced serious treatment-related adverse events (TRAEs) associated with either ivonescimab or chemotherapy. There were no ivonescimab-related deaths and one ivonescimab-related discontinuation, supporting the tolerability and ability to manage adverse events. “In this expansion cohort of treatment-naïve patients with metastatic colorectal cancer, the addition of ivonescimab to mFOLFOX6 delivered deep and durable response rates that compare favorably to historical benchmarks seen with chemotherapy alone or in combination with anti-VEGF therapies,” said David Berz, M.D., Ph.D., medical oncologist, Founder of Valkyrie Clinical Trials and an investigator in the AK112-206 study. “While progression-free survival remains immature, the high proportion of patients who were progression-free at nine months is encouraging, and the safety profile was consistent with established standards of care. These results support the potential of this dual-targeted approach to improve outcomes in this diff

// // Overall Survival Data to be Featured at ASCO 2026 Plenary Session as Late-Breaking Abstract from HARMONi-6, a Phase III Study in 1L Squamous NSCLC in China Update Conference Call to be Held on June 1, 2026 after ASCO Plenary Session HARMONi-3 Squamous Cohort of Global Phase III 1L NSCLC Study: Final PFS Data Expected in Second Half of 2026 with Interim OS Analyses Planned HARMONi-3 Non-Squamous Cohort of Global Phase III 1L NSCLC Study: PFS Data Expected in the First Half 2027 MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today reports its financial results and provides an update on clinical and operational progress for the first quarter ended March 31, 2026. Clinical & Operational 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: Since in-licensing ivonescimab, from Akeso Inc. (Akeso, HKEX Code: 9926.HK) in January 2023, over 4,000 patients have been treated with ivonescimab in clinical studies globally, and over 70,000 patients have been treated in the commercial setting with ivonescimab in China, as noted and updated by Akeso. Summit has rights to develop and commercialize ivonescimab in North America, South America, Europe, the Middle East, Africa, and Japan, while Akeso retains development and commercialization rights for remaining territories, including China. Summit is developing ivonescimab in non-small cell lung cancer (NSCLC) and colorectal cancer (CRC), specifically conducting multiregional 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 were previously treated with a third-generation EGFR tyrosine kinase inhibitor (TKI) HARMONi-3: Ivonescimab combined with chemotherapy in patients with first-

// // Three Poster Presentations Will Feature Updated Ivonescimab Data, including Intracranial Anti-Tumor Activity from the Global HARMONi Phase III Study MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) today announced that data for its novel, potential first-in-class investigational bispecific antibody, ivonescimab, will be presented at the 2026 European Lung Cancer Congress (ELCC 2026) in Copenhagen, Denmark. Three posters featuring updated ivonescimab data will be displayed on Friday, March 27 from 1:00 to 2:00 pm Central European Time. Data for HARMONi was generated and analyzed by Summit and for HARMONi-2 by our collaboration and licensing partner, Akeso Inc. (HKEX Code: 9926.HK). The first poster, “Intracranial Efficacy of Ivonescimab Plus Chemotherapy in Epidermal Growth Factor Receptor (EGFR) Tyrosine Kinase Inhibitor (TKI)-Resistant, EGFR-Mutated Non-Small Cell Lung Cancer (NSCLC) in the HARMONi Study” includes outcome data from patients with and without asymptomatic brain metastases at baseline enrolled in HARMONi (NCT06396065). These patients received either ivonescimab delivered in combination with chemotherapy, or chemotherapy alone in this global Phase III trial for patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who were previously treated with an EGFR TKI. Ivonescimab plus chemotherapy demonstrated an improvement in intracranial progression free survival (PFS) in patients with baseline brain metastases of 10.1 months compared to 6.5 months for chemotherapy (HR 0.53 (0.33-0.84); nominal p=0.0068). In patients who did not have baseline CNS metastases, the addition of ivonescimab also showed an improvement in intracranial PFS over control arm with 15.7 months compared to 11.6 months (HR 0.72 (0.55-0.94); nominal p=0.0172). No new safety signals were identified across baseline brain metastasis subgroups. The second poster, “Health-Related Quality of Life in Patients Previously Treated with an EGFR-TKI from HARMONi: A Phase 3 Trial of Ivonescimab vs Placebo Plus Chemotherapy” includes data from patients enrolled in HARMONi (NCT06396065). These patients received either ivonescimab delivered in combination with chemotherapy, or chemotherapy alone in this global Phase III trial for patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who were previously treated with an EGFR TKI. The third poster, “Health-Related Quality of Life with Ivonescimab Versus Pembrolizumab for PD-L1 Positive, NSCLC (HARMONi-2): a Randomised, Double-Blind, Phase 3 Study in China” includes data from patients enrolled in HARMONi-2 or AK112-303 (NCT05499390). These patients received either ivonescimab delivered as monotherapy, or pembrolizumab delivered as monotherapy in this Phase III study conducted exclusively in China for patients with locally advanced or metastatic NSCLC whose tumors have positive PD-L1 expression with all data collected and analyzed by Akeso. About the ELCC 2026 Posters Poster Title : Intracranial Efficacy of Ivonescimab Plus Chemotherapy in EGFR TKI-Resistant, EGFR-Mutated NSCLC in the HARMONi Study ELCC Presentation No.: 15P Session Date & Time: Friday, March 27, 1:00 to 2:00pm CET Poster Title : Health-Related Quality of Life in Patients Previously Treated with an EGFR-TKI from HARMONi: A Phase 3 Trial of Ivonescimab vs Placebo Plus Chemotherapy ELCC Presentation No.: 20P Session Date & Time: Friday, March 27, 1:00 to 2:00pm CET Poster Title : Health-Related Quality of Life with Ivonescimab Versus Pembrolizumab f

// // MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) today announced that it will participate in three upcoming investor conferences during March of this year. Members of the Summit leadership team will participate in individual investor meetings along with some fireside chats at the following conferences: TD Cowen's 46th Annual Health Care Conference in Boston on Monday, March 2, 2026 Fireside chat 2:30pm ET Jefferies Conference in Miami on Tuesday, March 10, 2026 Investor meetings only Citizens Life Sciences Conference in Miami on Wednesday, March 11, 2026 Fireside chat 2:15pm ET The fireside chats will be available live on our website: www.smmttx.com . An archived version of both presentations will be available on our website following the presentation. 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 outside of Summit’s license territories, 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. By design, 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 is intended to 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. We believe ivonescimab’s specifically engineered tetravalent structure (four binding sites) enables higher avidity (accumulated strength of multiple binding interactions) in the TME (Zhong, et al, iScience , 2025). 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, iScience , 2025) increasing to approximately 10 days at steady state dosing, is to improve upon previously established efficacy thresholds, side effects, and safety profiles associated with prior approved drugs to these targets. Ivonescimab was engineered by Akeso Inc. (HKEX Code: 9926.HK) and is currently utilized in multiple Phase III clinical trials. Over 4,000 patients have been treated with ivonescimab in clinical studies globally, and over 60,000 patients when considering those treated in a commercial setting in China, as noted by Akeso. There are currently 15 Phase III clinical studies that are either announced, ongoing, or have been completed studying ivonescimab, four of which are Summit-sponsored global studies, one of which is a multiregional study sponsored by a cooperative group, and ten of which are being or have been conducted in China by Akeso. Summit began its clinical development of ivonescimab in NSCLC

// // HARMONi-3 Squamous Cohort of Global Phase III 1L NSCLC Study: Interim PFS Analysis Planned in Q2 2026; Final PFS and Interim OS Data Planned in Second Half of 2026 HARMONi-3 Squamous Cohort Enrollment Screening Has Been Completed Phase III ILLUMINE Study in 1L PD-L1 Positive R/M HNSCC Sponsored by Cooperative Group, GORTEC, to Initiate; First Patient Expected in Early Q2 2026 US FDA Accepts BLA Filing Based on HARMONi Study; PDUFA Goal Action Date of November 14, 2026 First Patient Dosed in Revolution Medicines Clinical Trial Collaboration Evaluating Ivonescimab in Combination with RAS(ON) Inhibitors in RAS Mutant Tumors G SK Collaboration Clinical Trials Evaluating Ivonescimab in Combination with GSK’s Novel B7-H3, Risvutatug Rezetecan, Expected to Start Mid-2026 MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today reports its financial results and provides an update on clinical and operational progress for the fourth quarter and year ended December 31, 2025. Clinical & Operational 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: Since in-licensing ivonescimab (SMT112), from Akeso Inc. (Akeso, HKEX Code: 9926.HK) in January 2023, over 4,000 patients have been treated with ivonescimab in clinical studies globally, and over 60,000 patients have been treated in a commercial setting with ivonescimab in China, as noted by Akeso. Summit has rights to develop and commercialize ivonescimab in North America, South America, Europe, the Middle East, Africa, and Japan, while Akeso retains development and commercialization rights for remaining territories, including China. Summit is developing ivonescimab in non-small cell lung cancer (NSCLC) and colorectal cancer (CRC), specifically conducting multiregiona

// // Conference Call to be Held at 4:30pm ET MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) will host an earnings call to announce its fourth quarter and full year 2025 financial results and provide an operational update for the Company on Monday, February 23, 2026, after the market closes. Summit will host a live webcast of the earnings conference call at 4:30pm ET, which will be accessible through our website, www.smmttx.com . An archived edition of the session will be available on our website. 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 Palo Alto, California, Princeton, New Jersey, Dublin, Ireland, and Oxford, UK. For more information, please visit https://www.smmttx.com and follow us on X @SMMT_TX . 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, the expected timing of BLA submissions or FDA decisions, potential acquisitions, statements about the previously disclosed At-The-Market equity offering program (“ATM Program”), the expected proceeds and uses thereof, the Company’s estimates regarding stock-based compensation, 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,

// // MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today announced the grant of inducement awards of options to purchase a collective total of up to 257,368 shares of common stock. Awards were made to 20 new employees of the Company. The awards were granted as an inducement material to the new employees becoming employees of the Company in accordance with Nasdaq Listing Rule 5635(c)(4) and have been approved by the Company’s Compensation Committee. The inducement awards were granted on January 26, 2026. The options have a ten (10) year term and an exercise price of $16.56 per share, the closing price per share of the Company’s common stock as reported by Nasdaq on January 26, 2026. The options were granted from a pool of equity incentives reserved by the Compensation Committee on January 22, 2025 for issuance as inducements to new employees in accordance with Nasdaq Listing Rule 5635(c)(4). The options awarded to the recipients are subject to vesting in equal annual installments over a four-year period. The options awarded are subject to the terms of a stock option agreement to be executed by the recipient of the grant. 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 Palo Alto, California, Princeton, New Jersey, Dublin, Ireland, and Oxford, UK. For more information, please visit https://www.smmttx.com and follow us on X @SMMT_TX . 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, the expected timing of BLA submissions or FDA decisions, potential acquisitions, statements about the previously disclosed At-The-Market equity offering program (“ATM Program”), the expected proceeds and uses thereof, the Company’s estimates regarding stock-based compensation, 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 Th

BLA Filing Based on HARMONi Global Phase III Study Results PDUFA Goal Action Date of November 14, 2026 Significant Unmet Need Remains; Over 14,000 U.S. Patients Eligible for Treatment Each Year in This Setting Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today announced that the U.S. Food & Drug Administration (FDA) has accepted for filing Summit's Biologics License Application (BLA) seeking approval for ivonescimab in combination with chemotherapy in patients with epidermal growth factor receptor (EGFR)-mutated locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) post-tyrosine kinase inhibitor (TKI) therapy. The FDA provided a Prescription Drug User Fee Act (PDUFA) goal action date of November 14, 2026. The BLA was submitted based on the overall results of the Phase III HARMONi trial, which evaluated ivonescimab plus platinum-doublet chemotherapy compared to placebo plus platinum-doublet chemotherapy in patients with

Summit to Advance Development Opportunities of Ivonescimab with GSK’s Novel B7-H3 risvutatug rezetecan Multiple Solid Tumor Settings to Be Pursued with Clinical Trials Expected to Start in Mid-2026 Summit Therapeutics Inc. (NASDAQ: SMMT) today announced it has entered into a clinical trial collaboration with GSK plc (“GSK”, LSE/NYSE: GSK) to evaluate ivonescimab, a novel, investigational PD-1 / VEGF bispecific antibody, in combination with risvutatug rezetecan (also known as GSK’227), GSK’s novel investigational B7-H3 targeting antibody drug conjugate (ADC), across multiple solid tumor settings, including small cell lung cancer (SCLC). “We believe exploring new mechanisms and combinations with the potential to surpass current options for patients and physicians will have the most profound impact on those battling the toughest cancer challenges today,” stated Robert W. Duggan and Dr. Maky Zanganeh, Co-Chief Executive Officers of Summit. “With the goal of accelerating development of

Significant Unmet Need Remains in this Setting Over 14,000 Patients are Eligible for 2L+ Treatment in This Setting in the United States Each Year Summit Enters 2026 with Approximately $710 Million in Cash Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) today announced that it has submitted a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) seeking approval for ivonescimab, the novel, first-in-class investigational bispecific antibody, in combination with chemotherapy in second-line or later treatment of patients with epidermal growth factor receptor (EGFR)-mutated locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC). The BLA submission was based on the overall results of the global Phase III HARMONi trial. The BLA was submitted during the fourth quarter of 2025. “This BLA submission, the first for ivonescimab, marks a critical milestone for Summit, our global clinical development plan, and the many

Summit Therapeutics Inc. (NASDAQ: SMMT) ("Summit," "we," or the "Company") today announced the grant of inducement awards of options to purchase a collective total of up to 214,331 shares of common stock. Awards were made to seventeen new employees of the Company. The awards were granted as an inducement material to the new employees becoming employees of the Company in accordance with Nasdaq Listing Rule 5635(c)(4) and have been approved by the Company’s Compensation Committee. The inducement awards were granted on January 6, 2026. The options have a ten (10) year term and an exercise price of $18.66 per share, the closing price per share of the Company’s common stock as reported by Nasdaq on January 6, 2026. The options were granted from a pool of equity incentives reserved by the Compensation Committee on January 22, 2025 for issuance as inducements to new employees in accordance with Nasdaq Listing Rule 5635(c)(4). The options awarded to the recipients are subject to vesting in

Summit Therapeutics Inc. (NASDAQ: SMMT) (“Summit,” “we,” or the “Company”) today announced that it will participate in and present at the 44 th Annual J.P. Morgan Healthcare Conference in San Francisco, California, on Monday, January 12, 2026 at 9:45 AM PT. Robert W. Duggan, Chairman and Co-Chief Executive Officer, and Dr. Maky Zanganeh, President and Co-Chief Executive Officer, will present a corporate overview and a new update on the progress of our organization, including the development of our innovative investigational bispecific antibody, ivonescimab. Our leadership team will also participate in investor meetings during the conference. The presentation will be available live from our website: www.smmttx.com . An archived version of the presentation will be available on our website following the presentation. 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