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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 BTC Ivonescimab Plus Chemotherapy Reduced the Risk of Death by 25% Compared to Durvalumab Plus Chemotherapy; OS Hazard Ratio 0.75 Tolerable Safety Profile Consistent with Prior Clinical Trial Results U.S. Registration-Enabling Phase II / III Study of Ivonescimab in BTC starting in Q4 2026 through Summit’s ECOG-ACRIN Collaboration MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) today noted that its partner Akeso Inc. announced positive results from the Phase III HARMONi-GI1 study evaluating the novel, potential first-in-class investigational bispecific antibody ivonescimab plus chemotherapy compared with durvalumab plus chemotherapy as a first-line treatment for patients with advanced biliary tract cancer (BTC). These data are featured in today’s Presidential Symposium II at the European Society for Medical Oncology 2026 Congress (ESMO 2026) in Madrid, Spain. The HARMONi-GI1 presentation is entitled “ Ivonescimab plus chemotherapy versus durvalumab plus chemotherapy as first-line treatment for advanced biliary tract cancer: A randomized, controlled, double-blinded, phase 3 trial (HARMONi-GI1).” The HARMONi-GI1 study 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 primary endpoint of the HARMONi‑GI1 trial is overall survival (OS) and, as Akeso previously announced , a prespecified analysis showed the ivonescimab-based regimen achieved statistically significant and clinically meaningful superiority in OS compared to the durvalumab-based regimen. Clinically Meaningful Efficacy In the HARMONi-GI1 interim analysis of OS, ivonescimab in combination with chemotherapy demonstrated a statistically significant improvement when compared to durvalumab in combination with chemotherapy, with a hazard ratio (HR) of 0.75 (95% CI: 0.61, 0.92; one-sided p=0.0031). A clinically meaningful benefit was demonstrated across clinical subgroups, including age. Median follow-up time of the current data cut was 14.3 months. HARMONi-GI1 ITT (n=682): Ivonescimab + Chemo Durvalumab + Chemo Median Follow-up: 14.3 mos. (n=340) (n=342) Median OS 14.9 mos. (95% CI: 12.9, NE) 12.1 mos. (95% CI: 11.0, 13.4) OS Stratified HR 0.75 (95% CI: 0.61, 0.92; p = 0.0031 [one-sided]) 12-Month OS Rates 59.7% 50.7% 18-Month OS Rates 44.0% 32.5% ITT = intention-to-treat; n = number; mos.: months; CI=confidence interval; NE: not established Key secondary endpoints in the HARMONi-GI1 study were also met. Ivonescimab in combination with chemotherapy demonstrated a statistically significant improvement in progression-free survival (PFS) when compared with durvalumab in combination with chemotherapy, with an HR of 0.61 (95% CI: 0.51, 0.72; one-sided p HARMONi-GI1 ITT (n=682): Ivonescimab + Chemo Durvalumab + Chemo Median Follow-up: 14.3 mos. (n=340) (n=342) Median PFS 8.4 mos. (95% CI: 7.5, 9.3) 5.8 mos. (95% CI: 5.6, 7.2) PFS Stratified HR 0.61 (95% CI: 0.51, 0.72; p 6-Month PFS Rates 68.7% 49.3% 9-Month PFS Rates 49.3% 31.7% ORR 53.8% (95% CI: 48.4%, 59.2%) 32.5% (95% CI: 27.5%, 37.7%) DCR 91.5% (95% CI: 88.0%, 94.2%) 77.8% (95% CI: 73.0%, 82.1%) ITT=intention-to-treat; n = number; mos.: months; CI=confidence interval “HARMONi-GI1 marks an important milestone for patients with advanced biliary tract cancer and for the continued development of ivonescimab,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit. “This is the first known Phase III study in advanced biliary tract cancer to demonstrate overall survival superiority over an anti-PD-(L)1 therapy combined with chemotherapy. Moreover, as the first Phase III readout for ivonescimab beyond non-small cell lung cancer, the HARMONi-GI1 results further reinforce the potential

Research Will Use Lunit’s AI-powered Pathology Platform to Analyze H&E Whole-Slide Images and Generate Scalable Insights into Tumor Microenvironment Biology MIAMI & SEOUL, South Korea--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) and Lunit Inc. (KRX: 328130) today announced a research agreement to evaluate the use of Lunit SCOPE IO, Lunit’s AI-powered pathology platform, for tumor microenvironment analysis in support of Summit’s immuno-oncology development programs with ivonescimab. The effort will focus on applying Lunit SCOPE IO to hematoxylin and eosin-stained (H&E) whole-slide images to characterize tumor microenvironment features. The companies aim to explore how AI-powered pathology analysis can support biomarker discovery, patient stratification or selection, and a deeper biological understanding of response to ivonescimab therapies. Summit is developing ivonescimab, a novel, potential first-in-class investigational PD-1 / VEGF bispecific antibody, in several solid tumors. Lunit SCOPE IO is designed to support immuno-oncology research and biomarker development through AI-powered analysis of H&E slides, enabling scalable assessment of tumor microenvironment features without requiring additional stains or assays. “Understanding the tumor microenvironment is increasingly important as immuno-oncology moves beyond single-axis checkpoint inhibition toward more complex mechanisms and combinations,” said Allen Yang, MD, PhD, Chief Research and Development Strategy Officer of Summit. “We are pleased to work with Lunit to explore how AI-powered pathology can help generate deeper, more scalable insights from routine tissue samples and inform the continued development of ivonescimab.” “Summit is at the forefront of next-generation immuno-oncology development, and we are excited to support its efforts with Lunit SCOPE IO,” said Brandon Suh, Lunit CEO. “By extracting quantitative, spatially resolved immune and tumor microenvironment features from standard H&E slides, we believe SCOPE IO can help biopharma partners better understand which patients may benefit from immuno-oncology therapies and why.” This agreement reflects the growing importance of computational pathology in oncology drug development. Routine H&E slides contain rich information about tumor architecture, immune infiltration, stromal organization, and spatial interactions within the tumor microenvironment. However, traditional manual assessment can be difficult to scale and may not fully capture the quantitative and spatial complexity of the tumor-immune interface. AI-powered analysis offers the potential to convert these routinely generated pathology images into reproducible, high-dimensional biomarker data. The companies expect the work to generate tumor microenvironment insights that may inform future translational research, exploratory biomarker strategies, and clinical development planning. No clinical outcome data are being announced as part of this release. Lunit SCOPE products are for research use only. Not for use in diagnostic procedures or decisions. 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 design 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. Summit believes ivonescimab’s specifically engineered tetravalent structure (four binding sites) e

Highlights Include Phase II Data Supporting Clinical Development Expansion for Ivonescimab MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced that ivonescimab data will be featured in numerous presentations at the European Society for Medical Oncology 2026 Congress (ESMO 2026), taking place October 23-27, 2026, in Madrid, Spain. Across 10 presentations at ESMO 2026, ivonescimab data will span a broad range of tumor types, led by positive overall survival findings from Akeso Inc.’s Phase III HARMONi-GI1 study of ivonescimab plus chemotherapy compared to durvalumab plus chemotherapy in first-line advanced biliary tract cancer, which is selected as a Late-Breaking Abstract for the Presidential Symposium. HARMONi-GI1 is a multi-center, Phase III study conducted in China and sponsored by Akeso, with all relevant data exclusively generated, managed, and analyzed by Akeso. On October 21 , Summit and ECOG-ACRIN Cancer Research Group announced the initiation of the open-label Phase II/III EA2251 study, which plans to enroll patients in the U.S. who will be randomized to receive ivonescimab in combination with gemcitabine and cisplatin, or pembrolizumab or durvalumab in combination with gemcitabine and cisplatin as the established standard-of-care comparator regimen. Activation of clinical trial sites is expected to begin in the fourth quarter of 2026. Additional data include findings from investigator-sponsored trials (ISTs). A rapid oral presentation and a proffered paper will feature ivonescimab-based regimens in first-line recurrent/metastatic thymic carcinoma and advanced renal cell carcinoma, respectively. The program also highlights emerging endometrial cancer (EC) data, alongside continued development in gastrointestinal cancers such as esophageal, gastric/GEJ, and pancreatic cancers; glioblastoma; and head and neck squamous cell carcinoma. In a Phase II study in EC conducted at Memorial Sloan Kettering Cancer Center in New York, NY, ivonescimab monotherapy met the study’s primary endpoint for objective response rate with a manageable safety profile without new safety signals in previously treated patients with second-line and later EC. The strength of these results supported expansion of the IST led by Drs. Maria Rubinstein, MD, and Vicky Makker, MD, and provided a meaningful signal to inform opportunities for further development of ivonescimab in EC. “The breadth of the ivonescimab data at ESMO underscores the expanding body of clinical evidence across a diverse range of tumor types and treatment settings,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “Our ambition for ivonescimab extends beyond any single indication. We are focused on advancing a rigorous clinical development program to determine where this novel IO bispecific antibody could make a meaningful difference for patients. We look forward to engaging with the global oncology community on these data at ESMO 2026.” The ESMO 2026 ivonescimab presentations are listed below by tumor type: Biliary Tract Cancer Presidential Symposium Presentation: Ivonescimab plus chemotherapy versus durvalumab plus chemotherapy as first-line treatment for advanced biliary tract cancer: a randomized, controlled, double-blinded, phase 3 trial (HARMONi-GI1) Presidential Symposium II, Oct 25, 5:42-5:54 pm CET, Abstract #LBA8 Endometrial Cancer Poster: A phase 2 study of ivonescimab (PD1/VEGF bispecific antibody) for the treatment of endometrial cancer (EC) Abstract #1266P Esophageal Squamous Cell Carcinoma Poster: Ivonescimab (AK112) plus chemotherapy as first-line treatment for advanced or metastatic esophageal squamous cell carcinoma: A phase 2 single-arm study Abstract #2908P Gastric and GEJ Adenocarcinoma Poster: AK112 (PD-1/VEGF bispecific antibody) combined with low-dose radiotherapy and nab-paclitaxel as second-line therapy for advanced gastric or gastroesophageal junction adenocarcinoma: A prospective, multicen

Clinical Trial Site Activations in the United States Expected to Begin Q4 2026 MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced a clinical trial collaboration with the ECOG-ACRIN Cancer Research Group (ECOG-ACRIN) to evaluate ivonescimab, a novel, potential first-in-class investigational bispecific antibody, in a registration-enabling Phase II/III study in biliary tract cancer (BTC). The new study, EA2251 ( NCT07765433 ), is designed to evaluate the safety and efficacy of ivonescimab with chemotherapy compared to pembrolizumab or durvalumab plus chemotherapy in the first-line treatment of patients with advanced BTC. “Biliary tract cancer is often diagnosed at an advanced stage, and despite recent progress, there is a need for more effective first-line options that can extend survival and improve disease control,” said lead investigator Deirdre J. Cohen, MD, MS, Associate Professor of Medicine at the Icahn School of Medicine at Mount Sinai, Director of the Gastrointestinal Oncology Program for the Mount Sinai Health System and Co-Director of the Center of Excellence for Pancreatic Cancer at the Mount Sinai Tisch Cancer Center. “EA2251 will explore a novel therapeutic approach in the front-line setting by evaluating ivonescimab with chemotherapy against current immunotherapy-based standards of care.” The open-label Phase II/III EA2251 study plans to enroll patients in the U.S. who will be randomized to receive ivonescimab in combination with gemcitabine and cisplatin, or pembrolizumab or durvalumab in combination with gemcitabine and cisplatin as the established standard-of-care comparator regimen. The primary endpoint for the study is overall survival (OS). Activation of clinical trial sites is expected to begin in the fourth quarter of 2026. “We are honored to collaborate with ECOG-ACRIN on EA2251 as we continue to expand the development program for ivonescimab in areas of meaningful unmet need,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “The sponsorship and conduct of this registration-enabling study by a leading cooperative oncology group underscores the scientific interest in evaluating ivonescimab in difficult-to-treat cancers, including BTC, and supports Summit’s commitment to building a robust body of clinical evidence across multiple tumor types and treatment settings.” For additional information on EA2251, please see ECOG-ACRIN’s accompanying press release . EA2251 is the second Phase III study of ivonescimab in BTC; the first is HARMONi-GI1. In August 2026, Akeso Inc. announced the randomized Phase III HARMONi-GI1 study (AK112-309) evaluating ivonescimab plus chemotherapy compared with durvalumab plus chemotherapy as a first-line treatment for patients with BTC achieved statistically significant and clinically meaningful superiority in the primary endpoint of OS compared to the durvalumab-based regimen at a pre-specified interim analysis. Detailed results from HARMONi-GI1 will be presented at the European Society for Medical Oncology 2026 Congress (ESMO 2026) on Sunday, October 25, during the Presidential Symposium from 4:30pm – 6:15pm CET (11:30am – 1:15pm EDT). HARMONi-GI1 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. About Biliary Tract Cancer Biliary tract cancer (BTC) is a rare and aggressive group of gastrointestinal (GI) cancers that includes intrahepatic, perihilar, and distal cholangiocarcinoma as well as gallbladder cancer. 1 Because BTC often develops with few clear early symptoms, approximately 30% to 50% of patients are diagnosed after the disease has spread, when curative surgery is often no longer an option. 2 Prognosis remains poor, with five-year survival rates estimated to be less than 5% for patients diagnosed with distant-stage BTCs. 3,4 Despite recent progress in the treatment of advanced BTC, the

SMT112-216 Is a Randomized Multiregional Phase II Study Evaluating Ivonescimab Alone and in Combination with Cadonilimab or Ipilimumab in Previously Untreated Advanced ccRCC Study Is Being Conducted in Collaboration with Summit’s Partner Akeso, with Clinical Trial Sites in the U.S. and China MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced the initiation and opening of clinical trial sites of a multiregional Phase II study of ivonescimab, a novel, potential first-in-class investigational PD-1 / VEGF bispecific antibody, in previously untreated advanced clear cell renal cell carcinoma (ccRCC), the most common form of kidney cancer. The study (SMT112-216 / AK112-216 / NCT07877194 ) is being conducted in collaboration with Summit’s partner, Akeso Inc. SMT112-216 is a randomized, open-label Phase II clinical study designed to evaluate the safety and efficacy of multiple ivonescimab-based treatment approaches in patients with incurable locally advanced or metastatic ccRCC who have not received prior systemic therapy for advanced disease. The study plans to enroll approximately 100 patients at clinical trial sites in the U.S. and China. Participants will be randomized to receive ivonescimab in combination with cadonilimab, ivonescimab in combination with ipilimumab, ivonescimab monotherapy, or nivolumab plus ipilimumab as an established standard-of-care comparator regimen. Cadonilimab is an investigational PD-1 / CTLA-4 bispecific antibody developed by Akeso. This study is in addition to Summit’s clinical trial collaboration with Arcus Biosciences evaluating ivonescimab in combination with casdatifan, a HIF2α inhibitor, in a similar ccRCC setting. “In collaboration with Akeso, SMT112-216 reflects an important part of our shared strategy to evaluate ivonescimab across multiple treatment approaches, including combination regimens, in tumor types where meaningful unmet needs remain,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit Therapeutics. “As we continue to build a broad development program beyond lung, SMT112-216 adds to a growing body of studies in genitourinary and other malignancies that support our strategy to advance ivonescimab where there is strong scientific rationale.” “Ivonescimab’s dual targeting of PD-1 and VEGF is especially relevant in renal cell carcinoma, where both pathways have been shown to be valid targets to impact the course of the disease,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “Evaluating multiple ivonescimab-based regimens in the treatment-naïve incurable setting gives us the opportunity to assess ivonescimab’s dual mechanism early in the treatment journey, where immune-based combinations are well established and a differentiated immuno-oncology approach could be meaningful for patients.” 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, treatment options include immunotherapy-based combinations and targeted therapies. 4 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

MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today announced the successful closing of AstraZeneca’s (LSE/STO/NYSE: AZN) strategic equity investment in Summit. The equity investment will support continued acceleration of the development of ivonescimab, a novel, potential first-in-class investigational PD-1 / VEGF bispecific antibody. Pursuant to the terms of the Securities Purchase Agreement entered into by Summit and AstraZeneca, AstraZeneca purchased an aggregate of approximately 108,955 shares of preferred stock convertible into shares of common stock of Summit at a 1:1,000 ratio. The investment by AstraZeneca totaled $2.0 billion. At the conversion ratio, the investment represents a common stock price equal to $18.36, representing a premium over the closing trading price on the day the investment was announced. For additional details on the financial terms, please refer to the Summit press release issued on September 28, 2026. “This investment reflects AstraZeneca’s confidence in Summit and in ivonescimab’s potential to redefine cancer treatment,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit Therapeutics. “We share a resolute vision for what may be possible for patients, and this strategic relationship strengthens our ability to pursue that vision with urgency, purpose, and an unwavering commitment to meaningfully improving outcomes.” The additional funds will allow for the accelerated development of ivonescimab across a number of solid tumor settings, including combinations with antibody drug conjugates (ADCs) such as those collaborations announced last week with sonesitatug vedotin (Sone-Ve) and Datroway® (datopotamab deruxtecan). Baker Hostetler LLP is serving as legal advisor to Summit. 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 design 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. Summit believes 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 5,000 patients have been treated with ivonescimab in clinical studies globally, and over 100,000 patients when considering those treated in a commercial setting in China, as noted by Akeso. There are currently 16 Phase III clinical studies that are either announced, ongoing, or have been completed studying ivonescimab, five of which are Summit-sponsored global studies, one of which is a multiregional study sponsored by a cooperative group, and 10 of which are bein

Collaboration Intends to Evaluate Ivonescimab in Combination with Datroway across Multiple Tumor Types Starting with a Phase III Study in First-Line Triple Negative Breast Cancer MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) today announced a clinical trial collaboration agreement with Daiichi Sankyo (TSE: 4568) and AstraZeneca (LSE/STO/NYSE: AZN) to evaluate ivonescimab, a novel, potential first-in-class investigational PD-1 / VEGF bispecific antibody, in combination with Datroway ® (datopotamab deruxtecan), a TROP2-directed antibody drug conjugate (ADC), across multiple solid tumor settings, intending to include breast and lung cancer. The companies intend to begin with a Phase III trial in first-line triple-negative breast cancer (TNBC). “We believe this collaboration with Daiichi Sankyo and AstraZeneca reflects increasing conviction in ivonescimab’s potential as a foundational next-generation immunotherapy and advances our ambition for ivonescimab to become the global PD-1 / VEGF partner of choice for novel combinations,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “Beginning with a Phase III study in first-line triple negative breast cancer, this collaboration represents an important expansion of Summit’s global development program into breast cancer and a path for additional solid tumor settings.” Under the terms of the agreement, each company will contribute their respective therapies for the planned combination trials which will be sponsored by AstraZeneca or Daiichi Sankyo. AstraZeneca, Daiichi Sankyo, and Summit will each contribute to trial costs, and each company will retain development and commercial rights to their respective medicines. “At Daiichi Sankyo, we are focused on maximizing the potential of our DXd antibody drug conjugate portfolio through innovative combinations and strategic collaborations that support the continued advancement of our pipeline,” said John Tsai, MD, Global Head, R&D, Daiichi Sankyo. “We are encouraged by the opportunity to explore ivonescimab in combination with Datroway to potentially deliver clinically meaningful benefit to patients.” “Central to our strategy to transform cancer outcomes is harnessing the power of immunotherapy and antibody drug conjugate combinations to drive deeper, more durable responses,” said Susan Galbraith, Executive Vice President, Oncology Hematology R&D, AstraZeneca. “We believe the combination of Datroway and ivonescimab has the potential to make a meaningful difference in multiple tumor types including lung and breast cancers.” Datroway is a specifically engineered TROP2-directed DXd ADC discovered by Daiichi Sankyo and being jointly developed and commercialized by Daiichi Sankyo and AstraZeneca. Designed using the proprietary DXd ADC Technology of Daiichi Sankyo, Datroway is one of seven DXd ADCs in the oncology pipeline of Daiichi Sankyo. 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 design 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. Summit believes 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 int

Investment in Preferred Shares Convertible to Common Equity, Equivalent to a Per-Share Price of Summit’s Common Stock of $18.36, Representing a Premium over Today’s Closing Trading Price Summit Also Enters into Clinical Trial Collaboration with AstraZeneca to Evaluate Ivonescimab in Combination with Sonesitatug Vedotin in Multiple Gastrointestinal Cancers Summit & AstraZeneca Plan to Enter into a Clinical Trial Collaboration Combining Ivonescimab with Multiple AstraZeneca ADCs and Other Cancer Medicines MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) today announced key developments important to the company’s progress towards achieving its goal of making a significant difference in the lives of patients with cancer. Specifically, Summit has established agreements with AstraZeneca (LSE/STO/NYSE: AZN) for a strategic equity investment in Summit and a clinical collaboration focused on ivonescimab and sonesitatug vedotin (sone-ve). Moreover, Summit and AstraZeneca intend to evaluate ivonescimab with an additional set of AstraZeneca’s cancer medicines, including other antibody drug conjugates (ADCs). Ivonescimab is a novel, potential first-in-class investigational PD-1 / VEGF bispecific antibody. AstraZeneca Equity Investment in Summit Summit and AstraZeneca have entered into an agreement whereby AstraZeneca will make an equity investment of $2.0 billion in convertible preferred shares. At the conversion ratio, the investment represents a common stock price equal to $18.36 representing a premium over today’s closing price. “This significant investment, as well as the collaboration, is a powerful validation of the potential of ivonescimab,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit Therapeutics. “We are proud to welcome AstraZeneca as a strategic investor as we continue to work with purposeful urgency to make a significant difference for patients with cancer by improving outcomes.” Summit – AstraZeneca Clinical Trial Collaboration: Ivonescimab and Sone-Ve Summit entered into a clinical collaboration agreement with AstraZeneca to evaluate sonesitatug vedotin in combination with ivonescimab with the intent to start studies in certain gastrointestinal (GI) cancer settings imminently. Sone-ve is a potential global first-in-class Claudin 18.2-targeting ADC with several ongoing trials underway in GI cancers. Under the terms of the clinical collaboration agreement, each company will contribute their respective compound for the combination studies to be conducted, and the parties will jointly contribute to the costs of such studies, which are intended to be sponsored by AstraZeneca. Each company will retain development and commercial rights to their respective molecules. “The developments announced today with AstraZeneca open an exciting new chapter in the advancement of ivonescimab,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “With a growing body of evidence supporting ivonescimab’s differentiated PD-1 / VEGF bispecific approach, we look forward to further broadening the development plan of ivonescimab and initiating new clinical trials exploring the potential to combine ivonescimab with promising novel anti-cancer compounds, including ADCs, to bring together complementary approaches to tumor-cell killing, antitumor immunity, and the tumor microenvironment.” AstraZeneca recently reported positive high-level results from the CLARITY-Gastric01 trial for sone-ve in 2nd and later-line Claudin18.2-positive advanced gastric cancers demonstrating a statistically significant and clinically meaningful improvement in overall survival (OS) versus investigator’s choice of therapy. Results from this trial will be presented at the European Society for Medical Oncology Congress 2026 in a Presidential Symposium alongside the HARMONi-GI1 trial, an Akeso-sponsored trial from China in which ivonescimab plus chemotherapy demonstrated a statistically significant and c

HARMONi-GI1 Conducted in China by Akeso Is First Known Phase III Study in Advanced BTC to Demonstrate OS Superiority vs. Anti-PD-(L)1 Plus Chemotherapy First Phase III Ivonescimab Readout beyond NSCLC Demonstrates Significant OS Benefit MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) today noted that data from the Phase III HARMONi-GI1 trial, conducted in China and sponsored by Akeso, Inc., featuring the novel, potential first-in-class investigational bispecific antibody ivonescimab, will be featured as part of the Presidential Symposium II at the European Society for Medical Oncology 2026 Congress (ESMO 2026) which takes place October 23–27, 2026, in Madrid, Spain. The presentation will take place on Sunday, October 25 during the Presidential Symposium from 4:30pm – 6:15pm CET (11:30am – 1:15pm EDT). The HARMONi-GI1 study is evaluating ivonescimab plus chemotherapy compared with durvalumab plus chemotherapy as a first-line treatment for patients with advanced biliary tract cancer (BTC). HARMONi-GI1 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. On August 25, 2026, Akeso announced topline results from HARMONi-GI1. Akeso reported that, at a pre-specified interim analysis, the ivonescimab-based regimen achieved statistically significant and clinically meaningful superiority in the primary endpoint of overall survival (OS) compared to the durvalumab-based regimen. The study also met the key secondary endpoints of progression-free survival (PFS) and objective response rate (ORR). About the ESMO 2026 Presidential Symposium Presentation Presidential Symposium Presentation Presentation Title : Ivonescimab plus chemotherapy versus durvalumab plus chemotherapy as first-line treatment for advanced biliary tract cancer: a randomized, controlled, double-blinded, phase 3 trial (HARMONi-GI1) Presenter: Jian Zhou, MD (Shanghai, China) ESMO Presentation No.: Presidential Symposium II, LBA8 Session Date & Time: Sunday, October 25, 2026, 4:30pm – 6:15pm CET (11:30am – 1:15pm EDT) In China, ivonescimab is approved and commercially available for indications in non-small cell lung cancer (NSCLC). Ivonescimab remains investigational and is not approved by any regulatory authority in Summit’s license territories, including the United States and Europe. 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 design 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. Summit believes 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 ivonescimab’s design, together with a half-life of 6 to 7 days after the first dose (Zhong, et al , iScience, 2025) and increasing to approximately 10 days at steady state dosing, is to improve upon previously established efficacy thresholds, side effects, and safety profiles assoc

Sustained OS Improvement Seen with Longer Follow-Up in Western Patients, Consistent across Geographic Regions; No New Safety Signals Observed Akeso-Sponsored HARMONi-2 OS Data Also Presented at WCLC 2026; Additional Data from Landmark China-Only Study Included Herein MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (Nasdaq: SMMT) announced that updated overall survival (OS) results from the global Phase III HARMONi clinical trial featuring the novel, potential first-in-class investigational bispecific antibody ivonescimab were presented today at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer (WCLC 2026) in Seoul, Republic of Korea. As Summit previously announced on July 22, 2026, ivonescimab plus platinum-doublet chemotherapy in the HARMONi trial continued to show a positive OS trend and a consistent efficacy and safety profile in Asian and western patients when compared to placebo plus chemotherapy. “Updated results from the global Phase III HARMONi study show that ivonescimab combined with chemotherapy continued to demonstrate a consistent overall survival improvement compared with placebo plus chemotherapy in patients with EGFR-mutated non-small cell lung cancer following prior treatment with a third-generation EGFR TKI,” said Antonio Passaro, M.D., Ph.D., Director of the Division of Thoracic Oncology, European Institute of Oncology (IEO) in Milan, Italy, and presenting author. “Importantly, with longer follow-up, the survival improvement observed in western patients was consistent with the global population, reinforcing the relevance of these results across geographic regions in a setting where patients continue to need additional treatment options after progression on EGFR-targeted therapy.” HARMONi Detailed Efficacy and Safety Results The HARMONi study is evaluating ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with epidermal 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, the other being OS. 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 which was less than the median OS. An additional analysis was performed with a data cut-off date in June 2026, whereby most western patients have discontinued or completed two years of treatment (median follow-up time 23.2 months for western patients). Median follow-up time for Asian patients was 32.7 months (this was reached in April 2025 and Asian patient data was locked at the time of that analysis). The updated June 2026 analysis continued to show consistent, favorable OS results, with an OS hazard ratio of 0.76 (95% CI: 0.61 – 0.95; nominal p=0.0151) in the global intention-to-treat (ITT) population. An OS hazard ratio of 0.76 was demonstrated in the western patient subgroup (95% CI: 0.52 – 1.10), which was consistent with the ITT population and Asian subgroup. Global ITT 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) Median OS, ITT 16.8 mos 14.0 mos 16.8 mos 14.0 mos 16.8 mos 14.0 mos Hazard Ratio, ITT 0.79 (95% C

Ivonescimab Reduced the Risk of Death by 27% Compared to Pembrolizumab HARMONi-2 Demonstrated an Improvement in Median Overall Survival of 8.2 Months PD-L1 High Expression Subgroup: Hazard Ratio = 0.58 Summit is Conducting Global Phase III HARMONi-7 Study in Patients with PD-L1 High-Expressing NSCLC MIAMI--(BUSINESS WIRE)-- Summit Therapeutics Inc. (NASDAQ: SMMT) today noted that its partner Akeso Inc. announced that updated data, including overall survival (OS), from the randomized, double-blind Phase III HARMONi-2 trial featuring the novel, potential first-in-class investigational bispecific antibody ivonescimab is being presented at the International Association for the Study of Lung Cancer’s (IASLC) 2026 World Conference on Lung Cancer (WCLC 2026) in Seoul, Republic of Korea. The HARMONi-2 presentation entitled, Overall Survival Analysis From HARMONi-2: Ivonescimab vs Pembrolizumab as First-Line Treatment for PD-L1-Positive NSCLC , evaluated ivonescimab monotherapy compared to pembrolizumab monotherapy in patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) whose tumors have positive PD-L1 expression (PD-L1 Score > 1%). HARMONi-2 (AK112-303) 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 results will be presented by Professor Caicun Zhou, MD, PhD, Chief Physician and Director of the Department of Medical Oncology at Shanghai Pulmonary Hospital, Tongji University School of Medicine, and President of IASLC, on Tuesday September 15, 2026. Clinically Meaningful Efficacy In this protocol-specified interim analysis of OS, a secondary endpoint in the HARMONi-2 study, ivonescimab monotherapy demonstrated a statistically significant and clinically meaningful improvement compared to pembrolizumab monotherapy, achieving a hazard ratio (HR) of 0.73 (95% CI: 0.57, 0.95; p=0.009). A clinically meaningful benefit was demonstrated across important clinical subgroups, including those with PD-L1 low expression (PD-L1 Score 1-49%) and PD-L1 high expression (PD-L1 Score ≥ 50%), along with those with squamous and non-squamous histologies. HARMONi-2 ITT (n=398) Ivonescimab Pembrolizumab Median Follow-up: 36.0 mos (n=198) (n=200) Median OS 30.8 mos 22.6 mos OS Stratified HR 0.73 (95% CI: 0.57, 0.95; p=0.009) ITT = i ntention- t o- t reat population; mos = months; CI = confidence interval HARMONi-2 Subgroup Analyses; Ivonescimab vs. Pembrolizumab Ivonescimab vs. Pembrolizumab Descriptive, not formally powered PD-L1 High (PD-L1 Score ≥50%) HR = 0.58 n=168 (95% CI: 0.38, 0.89) PD-L1 Low (PD-L1 Score 1-49%) HR = 0.85 n=230 (95% CI: 0.61, 1.18) Squamous Histology HR = 0.65 n=181 (95% CI: 0.45, 0.95) Non-Squamous Histology HR = 0.79 n=217 (95% CI: 0.55, 1.14) NR = not reached; mos = months; CI=confidence interval; n = number Manageable Safety Profile In this analysis, ivonescimab continued to demonstrate an acceptable and manageable safety profile in the HARMONi-2 study, which was consistent with previous Phase III studies of ivonescimab. No additional safety signals were noted in the HARMONi-2 study in this current data cut with longer treatment duration (median of 14 cycles of ivonescimab vs. 10 cycles of pembrolizumab) compared to the previous data cut. Treatment-Related Adverse Events Ivonescimab (n=198) Pembrolizumab (n=200) Median follow-up: 36.0 mos Serious TRAEs, n (%) 59 (29.9) 43 (21.6) TRAEs Leading to Discontinuation, n (%) 8 (4.1) 10 (5.0) TRAEs = treatment-related adverse events; n = number; mos = months Akeso received marketing authorization for ivonescimab from China’s National Medical Products Administration (NMPA) based on the results of HARMONi-2 in April 2025. In the study’s primary analysis, ivonescimab monotherapy demonstrated a statistically significant improvement in the trial’s primary endpoint, progression-free survival (PFS) by Independent Radiologic Review Committee

Summit is Conducting HARMONi-7 in Patients with PD-L1 High-Expressing NSCLC Summit Therapeutics Inc. (NASDAQ: SMMT) today noted that its partner Akeso Inc. announced positive overall survival (OS) results from the randomized, double-blind Phase III HARMONi-2 study evaluating ivonescimab monotherapy against pembrolizumab monotherapy in patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) whose tumors have positive PD-L1 expression. HARMONi-2 (AK112-303) 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. In this preplanned analysis of OS, a secondary endpoint in the HARMONi-2 study, Akeso reported that ivonescimab monotherapy demonstrated a statistically significant improvement compared to pembrolizumab monotherapy. Results from this HARMONi-2 analysis are scheduled to be presented at an upcoming medical conference. Akeso received marketing

HARMONi-GI1 Conducted in China by Akeso Is First Known Phase III Study in Advanced BTC to Demonstrate OS Superiority vs. Anti-PD-(L)1 Plus Chemotherapy First Phase III Ivonescimab Readout beyond NSCLC Demonstrates Significant OS Benefit Summit Therapeutics Inc. (NASDAQ: SMMT) today noted that its partner Akeso Inc. announced positive topline results from the randomized Phase III HARMONi-GI1 study (AK112-309) evaluating ivonescimab plus chemotherapy compared with durvalumab plus chemotherapy as a first-line treatment for patients with advanced biliary tract cancer (BTC). HARMONi-GI1 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. Akeso reported that, at a pre-specified interim analysis, the ivonescimab-based regimen achieved statistically significant and clinically meaningful superiority in the primary endpoint of overall survival (OS) compared to the

First Immunotherapy-Based Regimen to Show Statistically Significant and Clinically Meaningful PFS Benefit in a Global Phase III Study of EGFR-Mutated NSCLC after Third-Generation EGFR TKI Progression Updated OS Data to Be Presented at WCLC 2026 Summit Therapeutics Inc. (NASDAQ: SMMT) today announced the publication of primary analysis results from the global Phase III HARMONi clinical trial in The Lancet Oncology . In HARMONi, ivonescimab in combination with platinum-doublet chemotherapy demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS) compared to placebo plus platinum-doublet chemotherapy in patients with epidermal growth factor receptor (EGFR)-mutated, locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) whose disease progressed following treatment with a third-generation EGFR tyrosine kinase inhibitor (TKI). The manuscript, titled “Ivonescimab plus chemotherapy versus placebo plus

Marks Third NMPA Approval in China for an Ivonescimab-Containing Regimen NMPA Approval Based on HARMONi-6 Clinical Trial Conducted by Akeso in China Ivonescimab in Combination with Chemotherapy Is the First Known Regimen to Achieve a Statistically Significant Overall Survival Benefit over an Anti-PD-(L)1 Antibody Combined with Chemotherapy in a Phase III Clinical Trial in NSCLC or Any Tumor Type Summit Therapeutics Inc. (NASDAQ: SMMT) today noted that, on August 12, 2026, its partner Akeso Inc. (Akeso, HKEX Code: 9926.HK) announced receipt of marketing authorization in China from the National Medical Products Administration (NMPA) for the use of ivonescimab, a novel, potential first-in-class investigational bispecific antibody, in combination with chemotherapy for the first-line treatment of patients with advanced squamous non-small cell lung cancer (NSCLC). This marks the third NMPA-approved indication for an ivonescimab-containing regimen in China since the molecule’s initial

HARMONi-GU1 Is First Global Registrational Clinical Trial of Ivonescimab in a Genitourinary (GU) Cancer, Adding to Global Phase III Ivonescimab Studies in NSCLC and CRC Clinical Trial Site Activations Globally Planned to Begin by Q4 2026 Summit Therapeutics Inc. (NASDAQ: SMMT) today announced the expansion of its global registration-enabling clinical development program for the novel, potential first-in-class investigational bispecific antibody ivonescimab, into urothelial carcinoma, or bladder cancer, with the initiation of the global, multi-regional Phase II/III HARMONi-GU1 trial. Summit is starting a randomized Phase II/III clinical study, HARMONi-GU1, to evaluate ivonescimab plus the antibody-drug conjugate (ADC) enfortumab vedotin (EV) compared to pembrolizumab plus EV as first-line therapy in patients with previously untreated locally advanced or metastatic urothelial carcinoma. The comparator arm regimen is widely considered the global standard of care. Global clinical trial

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 prospectus-eq_fi@jpmchase.com and postsalemanualrequests@broadridge.com ; Goldman Sachs & Co. LLC, Attention: Prospectus Department, 200 West Street, New York, NY 10282, by telephone at (866) 471-2526, or by email at Prospectus-ny@ny.email.gs.com ; 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