# EDGAR Filing Document

**Accession Number:** 0001599298
**File Stem:** 0001599298-26-000043
**Filing Date:** 2026-6
**Character Count:** 67130
**Document Hash:** 8ab2473adadfb142a16daaa67743b26f
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001599298-26-000043.hdr.sgml**: 20260601

**ACCESSION NUMBER**: 0001599298-26-000043

**CONFORMED SUBMISSION TYPE**: 8-K

**PUBLIC DOCUMENT COUNT**: 48

**CONFORMED PERIOD OF REPORT**: 20260530

**ITEM INFORMATION**: Other Events

**ITEM INFORMATION**: Financial Statements and Exhibits

**FILED AS OF DATE**: 20260601

**DATE AS OF CHANGE**: 20260601

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Summit Therapeutics Inc.
- **CENTRAL INDEX KEY:** 0001599298
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 371979717
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 8-K
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-36866
- **FILM NUMBER:** 261047072

**BUSINESS ADDRESS:**
- **STREET 1:** 601 BRICKELL KEY DRIVE
- **STREET 2:** SUITE 1000
- **CITY:** MIAMI
- **STATE:** FL
- **ZIP:** 33131
- **BUSINESS PHONE:** 305-203-2034

**MAIL ADDRESS:**
- **STREET 1:** 601 BRICKELL KEY DRIVE
- **STREET 2:** SUITE 1000
- **CITY:** MIAMI
- **STATE:** FL
- **ZIP:** 33131

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Summit Therapeutics plc
- **DATE OF NAME CHANGE:** 20150219

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Summit Corp plc
- **DATE OF NAME CHANGE:** 20140205

?xml version='1.0' encoding='ASCII'? smmt-20260530

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

**FORM 8-K**

**CURRENT REPORT**

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

Date of Report (Date of Earliest Event Reported): <u>May 30, 2026</u>

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

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Registrant's Telephone Number, Including Area Code: <u>(305) 203-2034</u>

Not applicable <br> (Former Name or Former Address, If Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (*see* General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

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

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| | | |
|:---|:---|:---|
| Title of Each Class | Trading Symbol(s) | Name of Each Exchange on Which Registered |
| Common stock, $0.01 par value per share | SMMT | The Nasdaq Stock Market LLC |

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

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

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|:---|:---|
| **Item 8.01** | **Other Events.** |

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On May 30, 2026, Summit Therapeutics Inc. (the "Company") issued a press release announcing new results from the AK112-206 trial ("AK112-206"), a global, open-label, multicenter Phase II study in first-line metastatic colorectal cancer co-sponsored by the Company and its partner, Akeso, Inc. ("Akeso"), featuring ivonescimab. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated by reference herein.

On May 31, 2026, the Company issued a press release noting that Akeso published results from the Phase III HARMONi-6 trial or AK112-306 ("HARMONi-6"). HARMONi-6 is a single region, multi-center Phase III study conducted in China sponsored by Akeso with all relevant data exclusively generated, managed, and analyzed by Akeso. A copy of the press release is attached as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated by reference herein.

The Company plans to utilize slides during its conference call scheduled for 7:00am ET on June 1, 2026, discussing the ivonescimab data from AK112-206 and HARMONi-6. A copy of the slides is attached as Exhibit 99.3 to this Current Report on Form 8-K and is incorporated by reference herein.

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| | |
|:---|:---|
| **Item 9.01** | **Financial Statements and Exhibits.** |

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(d) Exhibits

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| | |
|:---|:---|
| **<u>Exhibit Number</u>** | **<u>Description</u>** |
| 99.1 | <u>[Press Release, dated May 30, 2026](encouraging-globalxphase.htm)</u> |
| 99.2 | <u>[Press Release, dated May 31, 2026](ivonescimab-withxchemoth.htm)</u> |
| 99.3 | <u>[Presentation Slides for June 1, 2026 Conference Call](a20260601ascoupdatecalld.htm)</u> |
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) |

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**SIGNATURE**

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.

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| | | |
|:---|:---|:---|
| | **SUMMIT THERAPEUTICS INC.** | **SUMMIT THERAPEUTICS INC.** |
| Date: June 1, 2026 | By: | /s/ Manmeet S. Soni |
|  |  | Chief Operating Officer, Chief Financial Officer and Director |
|  |  | (Principal Financial Officer) |

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## Exhibit 99.1

![](encouraging-globalxphase001.jpg)

NEWS RELEASE Encouraging Global Phase II Ivonescimab Data in First-Line Metastatic Colorectal Cancer Presented at ASCO 2026 2026-05-30 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 Pro�le 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 �rst-line metastatic colorectal cancer (mCRC) co-sponsored by Summit and Akeso, featuring the novel, potential �rst-in-class investigational bispeci�c 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 1

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![](encouraging-globalxphase002.jpg)

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-o� 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 pro�le 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 pro�le was consistent with established standards of care. These results support the potential of this dual-targeted approach to improve outcomes in this di�cult-to-treat population and warrant further investigation." Ivonescimab continues to demonstrate an acceptable and manageable safety pro�le with no new safety signals observed in this study. This was consistent with previous studies of ivonescimab, including Phase II data in mCRC, and evidencing the potential for a favorable bene�t-risk pro�le for ivonescimab plus mFOLFOX6 in this setting. In this study, adverse events were manageable: all patients experienced at least one treatment-emergent adverse event (TEAE) related to either ivonescimab or chemotherapy with the most common events on both dosing arms being decreased neutrophil count, decreased white blood cell count, and anemia. "Metastatic colorectal cancer remains a signi�cant area of unmet need, where many patients continue to face limited durable treatment options," said Allen S. Yang, M.D., Ph.D., Chief R&D Strategy O�cer of Summit. "These 2

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![](encouraging-globalxphase003.jpg)

data add to the growing body of evidence supporting the potential of ivonescimab as a di�erentiated PD-1 / VEGF bispeci�c, and we are committed to advancing its development across multiple tumor types where we believe it may meaningfully improve patient outcomes." Summit is currently conducting HARMONi-GI3 (NCT07228832), a global Phase III clinical trial evaluating ivonescimab in combination with mFOLFOX6 chemotherapy compared with bevacizumab plus mFOLFOX6 chemotherapy in patients with �rst-line unresectable mCRC. This study is featured at this year's ASCO Annual Meeting in a Trials-in- Progress (TiP) presentation entitled, "A Randomized, Active-Controlled Phase 3 Study of Ivonescimab + FOLFOX Versus Bevacizumab + FOLFOX as First-Line Treatment of Metastatic Colorectal Cancer: HARMONi-GI3." About Colorectal Cancer Colorectal cancer (CRC), which includes cancers of the colon and rectum, is the third most commonly diagnosed cancer worldwide and the second leading cause of cancer-related death, with approximately 1.9 million new cases and more than 900,000 deaths reported globally in 2022. In the U.S., CRC remains a signi�cant health burden, with an estimated 158,850 new cases and 55,230 deaths projected in 2026. Prognosis is highly dependent on stage at diagnosis: while overall 5-year survival is approximately 65%, patients with metastatic disease have substantially poorer outcomes, with 5-year survival rates of approximately 13% for metastatic colon cancer and 18% for metastatic rectal cancer. These data underscore the urgent need for improved treatment options for patients with metastatic CRC (mCRC). CRC is biologically heterogeneous, with tumors broadly classi�ed based on microsatellite status. Approximately 80– 85% of colorectal cancers are microsatellite stable (MSS), also referred to as mismatch repair–pro�cient (pMMR) tumors. MSS/pMMR colorectal tumors are typically characterized by lower tumor mutational burden and an immune-cold phenotype, with limited responsiveness to immune checkpoint inhibitors. In metastatic disease, they represent the overwhelming majority of cases, accounting for approximately 95% of tumors. As a result, most patients with mCRC are not eligible for currently approved immunotherapy monotherapies and are treated with chemotherapy-based regimens, often in combination with targeted therapies such as anti-VEGF and anti-EGFR agents. 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 �rst-in-class investigational bispeci�c antibody combining the e�ects of immunotherapy via a blockade of PD-1 with the anti- angiogenesis e�ects associated with blocking VEGF into a single molecule. By design, ivonescimab displays unique cooperative binding to each of its intended targets with multifold higher a�nity to PD-1 when in the presence of VEGF. 1 2 2,3 4 5,6 5 3

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![](encouraging-globalxphase004.jpg)

This is intended to di�erentiate 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 speci�cally 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 bispeci�c 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 �rst dose (Zhong, et al, iScience, 2025) increasing to approximately 10 days at steady state dosing, is to improve upon previously established e�cacy thresholds, side e�ects, and safety pro�les 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 70,000 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 10 of which are being or have been conducted in China by Akeso. Summit began its clinical development of ivonescimab in NSCLC, commencing enrollment in 2023 in two multiregional Phase III clinical trials, HARMONi and HARMONi-3. In 2025, Summit began enrolling patients in HARMONi-7. Summit expanded its Phase III clinical development program into CRC in the fourth quarter of 2025 by initiating enrollment in HARMONi-GI3. HARMONi is a Phase III clinical trial evaluating ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who were previously treated with a third- generation EGFR TKI (e.g., osimertinib). Detailed results of the study were provided in September 2025, and a Biologics License Application (BLA) was submitted to the United States Food and Drug Administration (FDA) for marketing authorization, which the FDA accepted for �ling in January 2026; the goal Prescription Drug User Fee Act (PDUFA) date is November 14, 2026. HARMONi-3 is a Phase III clinical trial evaluating ivonescimab combined with chemotherapy compared to pembrolizumab combined with chemotherapy in patients with �rst-line metastatic, squamous or non-squamous NSCLC, irrespective of PD-L1 expression. The clinical trial is evaluating the two histologies as individual, separately powered cohorts with independent statistical powering. HARMONi-7 is a Phase III clinical trial evaluating ivonescimab monotherapy compared to pembrolizumab 4

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![](encouraging-globalxphase005.jpg)

monotherapy in patients with �rst-line metastatic NSCLC whose tumors have high PD-L1 expression. HARMONi-GI3 is a Phase III clinical trial evaluating ivonescimab in combination with chemotherapy compared with bevacizumab plus chemotherapy in patients with �rst-line unresectable metastatic CRC. ILLUMINE is a Phase III study being conducted by GORTEC, a cooperative group dedicated to Head and Neck Oncology, in recurrent / metastatic head and neck squamous cell carcinoma (r/m HNSCC). ILLUMINE is a three-arm Phase III clinical trial designed to evaluate ivonescimab monotherapy, as well as ivonescimab in combination with ligufalimab, Akeso's proprietary anti-CD47 monoclonal antibody, compared to monotherapy pembrolizumab in patients with PD-L1 positive r/m HNSCC. In addition, Akeso has recently had positive read-outs in three single-region (China), randomized Phase III clinical trials, HARMONi-A, HARMONi-2, and HARMONi-6, for ivonescimab in NSCLC, including a statistically signi�cant overall survival bene�t in HARMONi-A, with a manageable safety pro�le in each study. HARMONi-A was a Phase III clinical trial evaluating ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who have progressed after treatment with an EGFR TKI. HARMONi-2 is a Phase III clinical trial evaluating monotherapy ivonescimab against monotherapy pembrolizumab in patients with locally advanced or metastatic NSCLC whose tumors have positive PD-L1 expression. HARMONi-6 is a Phase III clinical trial evaluating ivonescimab in combination with platinum-based chemotherapy compared with tislelizumab, an anti-PD-1 antibody, in combination with platinum-based chemotherapy in patients with locally advanced or metastatic squamous NSCLC, irrespective of PD-L1 expression. Akeso is actively conducting multiple Phase III clinical studies in settings outside of NSCLC, including biliary-tract cancer, triple-negative breast cancer, head and neck squamous cell carcinoma, small cell lung cancer, colorectal cancer, and pancreatic cancer. Ivonescimab is an investigational therapy that is not approved by any regulatory authority in Summit's license territories, including the United States and Europe. Ivonescimab was initially approved for marketing authorization in China in May 2024. 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 5

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![](encouraging-globalxphase006.jpg)

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 o�ces 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. References: 1. World Health Organization. Colorectal cancer fact sheet. February 13, 2026. Accessed May 19, 2026. 2. National Cancer Institute, Surveillance, Epidemiology, and End Results (SEER) Program. Cancer Stat Facts: Colorectal Cancer. Accessed May 19, 2026. 3. American Cancer Society. Survival Rates for Colorectal Cancer (based on SEER 2014–2020 data). January 13, 2026. Accessed May 19, 2026. 4. Colorectal Cancer Alliance. Microsatellite Stability Biomarker (MSS). Accessed May 19, 2026. 5. Lieu CH. The use of immunotherapy in metastatic microsatellite-stable colorectal cancer. Hematol Oncol. 2022;20(12) . 6. Han YJ, Shao CY, Yao Y, et al. Immunotherapy of microsatellite stable colorectal cancer: resistance mechanisms and treatment strategies. Postgrad Med J. 2024;100:373–381. 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 o�ering 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 di�er 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 a�ecting the capital markets, general economic, industry, or political conditions, 6

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![](encouraging-globalxphase007.jpg)

including the e�ects 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 a�ect timing and status of our clinical trials and operations, whether preliminary results from a clinical trial will be predictive of the �nal 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�ecting government contracts and funding awards, availability of funding su�cient for the Company's foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of �lings that the Company makes with the Securities and Exchange Commission. Summit de�nes a "positive study" as a clinical study that with one or more prespeci�ed primary endpoints in which one of those endpoints achieves a statistically signi�cant bene�t according to the protocol or statistical analysis plan. Any change to our ongoing trials could cause delays, a�ect our future expenses, and add uncertainty to our commercialization e�orts, as well as to a�ect the likelihood of the successful completion of clinical development of ivonescimab. Accordingly, readers should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this press release represent the Company's views only as of the date of this release and should not be relied upon as representing the Company's views as of any subsequent date. The Company speci�cally disclaims any obligation to update any forward-looking statements included in this press release. Summit Therapeutics and the Summit Therapeutics logo are registered trademarks of Summit Therapeutics Inc. and/or its a�liates. Copyright 2026, Summit Therapeutics Inc. All Rights Reserved. Summit Investor Relations & Media Contacts: Nathan LiaBraaten Senior Director, Investor Relations Tracy Jones Director, Media & Public Relations investors@smmttx.com media@smmttx.com Source: Summit Therapeutics 7

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## Exhibit 99.2

![](ivonescimab-withxchemoth001.jpg)

NEWS RELEASE Ivonescimab with Chemotherapy Demonstrated a Statistically Signi�cant Overall Survival Bene�t Compared to Tislelizumab Plus Chemotherapy in 1L Treatment of Patients with Squamous NSCLC in the HARMONi-6 Study Conducted by Akeso in China 2026-05-31 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 Signi�cant and Clinically Meaningful Overall Survival Bene�t over an anti-PD- (L)1 Antibody Combined with Chemotherapy in a Phase III Clinical Trial in 1L NSCLC Tolerable Safety Pro�le 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 1

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![](ivonescimab-withxchemoth002.jpg)

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, �rst-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 signi�cant 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 E�cacy In the HARMONi-6 planned interim analysis of OS, ivonescimab in combination with chemotherapy demonstrated a statistically signi�cant improvement when compared to tislelizumab in combination with chemotherapy, with a hazard ratio (HR) of 0.66 (95% CI: 0.50, 0.87; p=0.0017). A clinically meaningful bene�t was demonstrated across clinical subgroups, including those with either PD-L1 negative or positive expression. OS rates at 24 months were 64.7% for those patients receiving ivonescimab plus chemotherapy compared to 48.6% for those receiving tislelizumab plus chemotherapy. Median follow-up time of the current data cut was 21.4 months. HARMONi-6 ITT (n=532): Median Follow-up: 21.36 mos. Ivonescimab + Chemo (n=266) Tislelizumab + Chemo (n=266) Median OS 27.89 mos. (95% CI: 27.89, NE) 23.69 mos. (95% CI: 20.11, NE) 24-Month OS Rates 64.7% 48.6% OS Strati�ed HR 0.66 (95% CI: 0.50, 0.87; p= 0.0017) mos.: months; NE: not established 2

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![](ivonescimab-withxchemoth003.jpg)

HARMONi-6 PD-L1 Subgroup Analyses Ivonescimab + Chemo vs. Tislelizumab + Chemo PD-L1 Negative (PD-L1 TPS <1%) OS strati�ed HR Ivonescimab + Chemo n=105; Tislelizumab + Chemo n=105 0.64 (95% CI: 0.43, 0.96) PD-L1 Positive (PD-L1 TPS >1%) OS strati�ed HR Ivonescimab + Chemo n=161; Tislelizumab + Chemo n=161 0.68 (95% CI: 0.46, 0.99) "For the �rst time, a Phase III clinical study has demonstrated a statistically signi�cant overall survival bene�t in front-line driver-mutation-negative non-small cell lung cancer compared to anti-PD-1 therapy in combination with chemotherapy," said Dr. Maky Zanganeh, President and Co-Chief Executive O�cer of Summit. "While this represents another study where ivonescimab has demonstrated a signi�cant OS bene�t, these data represent the answer to the question regarding ivonescimab and its ability to translate PFS bene�ts into the extension of lives for patients with cancer in the front-line setting compared to immunotherapy-based regimens." The HARMONi-6 study met its primary endpoint as announced in April 2025, showing a statistically signi�cant and clinically meaningful improvement in PFS. Detailed results for e�cacy and safety were presented at the European Society of Medical Oncology 2025 Congress (ESMO 2025) last October and published in The Lancet simultaneously. Safety Pro�le In this analysis, ivonescimab continued to demonstrate an acceptable and manageable safety pro�le in the HARMONi-6 study, which was consistent with previous Phase III studies of ivonescimab plus chemotherapy. No additional safety signals were noted in the HARMONi-6 study in this current data cut compared to the previous data cut presented. Treatment-related serious adverse events occurred in 41.4% of patients receiving ivonescimab in combination with chemotherapy and 34.3% of patients receiving tislelizumab in combination with chemotherapy. Most of the possibly VEGF-related adverse events occurring in the ivonescimab-plus-chemotherapy arm were classi�ed as Grade 1 or 2; Grade 3 or higher hemorrhage events were observed in 2.6% of patients in the ivonescimab-plus- chemotherapy arm compared to 0.8% of patients in the tislelizumab-plus-chemotherapy arm in this study. Treatment-related adverse events (TRAEs) leading to discontinuation in this study occurred in 5.3% of patients receiving ivonescimab plus chemotherapy compared to 4.5% for those receiving tislelizumab plus chemotherapy. In squamous NSCLC, VEGF-A monoclonal antibodies have had limited clinical development based on historical data demonstrating signi�cant risks of toxicity, including life-threatening hemorrhage and other bleeding complications. The results of this study further validate the unique mechanism of action of ivonescimab, including apparent key di�erences as compared to historical clinical studies where an anti-PD-1 monoclonal antibody and an anti-VEGF 3

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monoclonal antibody were administered separately. HARMONi-6 Clinical Trial Results Published in The Lancet The Lancet simultaneously published these �ndings in a manuscript titled, "Ivonescimab plus Chemotherapy for Squamous Non-small-cell Lung Cancer." "A heartfelt congratulations to our partner, Akeso, for their continuing, tremendous e�orts to make a signi�cant di�erence in the lives of patients with cancer," said Robert W. Duggan, Chairman and Co-Chief Executive O�cer of Summit. "The decision we made in December 2022 to enter into a partnership speci�cally with Akeso and accelerate the global clinical development plan of this potentially landscape-changing compound in ivonescimab is further validated with these groundbreaking results for patients facing high unmet medical needs. We look forward to continuing this positive momentum." Conference Call Summit will host a conference call and live webcast to discuss recent updates related to ivonescimab, including data released at ASCO, on Monday, June 1, 2026, at 7:00 a.m. ET. Conference call and webcast information is accessible through the company's website, www.smmttx.com. An archived edition of the webcast will be available on the website later in the day on Monday. 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 �rst-in-class investigational bispeci�c antibody combining the e�ects of immunotherapy via a blockade of PD-1 with the anti- angiogenesis e�ects associated with blocking VEGF into a single molecule. By design, ivonescimab displays unique cooperative binding to each of its intended targets with multifold higher a�nity to PD-1 when in the presence of VEGF. This is intended to di�erentiate 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 speci�cally 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 bispeci�c 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 �rst dose (Zhong, et al, iScience, 2025) increasing to approximately 10 days at steady state dosing, is to improve upon previously 4

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established e�cacy thresholds, side e�ects, and safety pro�les 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 70,000 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 10 of which are being or have been conducted in China by Akeso. Summit began its clinical development of ivonescimab in NSCLC, commencing enrollment in 2023 in two multiregional Phase III clinical trials, HARMONi and HARMONi-3. In 2025, Summit began enrolling patients in HARMONi-7. Summit expanded its Phase III clinical development program into CRC in the fourth quarter of 2025 by initiating enrollment in HARMONi-GI3. HARMONi is a Phase III clinical trial is evaluating ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who were previously treated with a third-generation EGFR TKI (e.g., osimertinib). Detailed results of the study were provided in September 2025, and a Biologics License Application (BLA) was submitted to the United States Food and Drug Administration (FDA) for marketing authorization, which the FDA accepted for �ling in January 2026; the goal Prescription Drug User Fee Act (PDUFA) date is November 14, 2026. HARMONi-3 is a Phase III clinical trial evaluating ivonescimab combined with chemotherapy compared to pembrolizumab combined with chemotherapy in patients with �rst-line metastatic, squamous or non-squamous NSCLC, irrespective of PD-L1 expression. The clinical trial is evaluating the two histologies as individual, separately powered cohorts with independent statistical powering. HARMONi-7 is a Phase III clinical trial evaluating ivonescimab monotherapy compared to pembrolizumab monotherapy in patients with �rst-line metastatic NSCLC whose tumors have high PD-L1 expression. HARMONi-GI3 is a Phase III clinical trial evaluating ivonescimab in combination with chemotherapy compared with bevacizumab plus chemotherapy in patients with �rst-line unresectable metastatic CRC. ILLUMINE is a Phase III study being conducted by GORTEC, a cooperative group dedicated to Head and Neck Oncology, in recurrent / metastatic head and neck squamous cell carcinoma (r/m HNSCC). ILLUMINE is a three-arm Phase III clinical trial designed to evaluate ivonescimab monotherapy, as well as ivonescimab in combination with ligufalimab, Akeso's proprietary anti-CD47 monoclonal antibody, compared to monotherapy pembrolizumab in 5

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patients with PD-L1 positive r/m HNSCC. In addition, Akeso has recently had positive read-outs in three single-region (China), randomized Phase III clinical trials, HARMONi-A, HARMONi-2, and HARMONi-6, for ivonescimab in NSCLC, including a statistically signi�cant overall survival bene�t in both the HARMONi-A and HARMONi-6 studies, and a manageable safety pro�le in each study. HARMONi-A was a Phase III clinical trial which evaluated ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who have progressed after treatment with an EGFR TKI. HARMONi-2 is a Phase III clinical trial evaluating monotherapy ivonescimab against monotherapy pembrolizumab in patients with locally advanced or metastatic NSCLC whose tumors have positive PD-L1 expression. HARMONi-6 is a Phase III clinical trial evaluating ivonescimab in combination with platinum-based chemotherapy compared with tislelizumab, an anti-PD-1 antibody, in combination with platinum-based chemotherapy in patients with locally advanced or metastatic squamous NSCLC, irrespective of PD-L1 expression. Akeso is actively conducting multiple Phase III clinical studies in settings outside of NSCLC, including biliary-tract cancer, triple-negative breast cancer, head and neck squamous cell carcinoma, small cell lung cancer, colorectal cancer, and pancreatic cancer. Ivonescimab is an investigational therapy that is not approved by any regulatory authority in Summit's license territories, including the United States and Europe. Ivonescimab was initially approved for marketing authorization in China in May 2024. 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 o�ces 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. 6

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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 o�ering 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 di�er 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 a�ecting the capital markets, general economic, industry, or political conditions, including the e�ects 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 a�ect timing and status of our clinical trials and operations, whether preliminary results from a clinical trial will be predictive of the �nal 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�ecting government contracts and funding awards, availability of funding su�cient for the Company's foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of �lings that the Company makes with the Securities and Exchange Commission. Summit de�nes a "positive study" as a clinical study that with one or more prespeci�ed primary endpoints in which one of those endpoints achieves a statistically signi�cant bene�t according to the protocol or statistical analysis plan. Any change to our ongoing trials could cause delays, a�ect our future expenses, and add uncertainty to our commercialization e�orts, as well as to a�ect the likelihood of the successful completion of clinical development of ivonescimab. Accordingly, readers should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this press release represent the Company's views only as of the date of this release and 7

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should not be relied upon as representing the Company's views as of any subsequent date. The Company speci�cally disclaims any obligation to update any forward-looking statements included in this press release. Summit Therapeutics and the Summit Therapeutics logo are registered trademarks of Summit Therapeutics Inc. and/or its a�liates. Copyright 2026, Summit Therapeutics Inc. All Rights Reserved. Summit Investor Relations & Media Contacts: Nathan LiaBraaten Senior Director, Investor Relations Tracy Jones Director, Media & Public Relations investors@smmttx.com media@smmttx.com Source: Summit Therapeutics 8

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## Exhibit 99.3

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Summit Therapeutics ASCO 2026 Update Call June 1, 2026 7:00am ET

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Forward Looking Statement Any statements in this presentation about the Company's future expectations, plans and prospects, including but not limited to, statements about the clinical and preclinical development of the Company's product candidates, entry into and actions related to the Company's partnership with Akeso Inc., 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 affecting government contracts and funding awards, availability of funding sufficient for the Company's foreseeable and unforeseeable operating expenses and capital expenditure requirements and other factors discussed in the "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of filings that the Company makes with the Securities and Exchange Commission. Summit defines a "positive study" as a clinical study that with one or more prespecified primary endpoints in which one of those endpoints achieves a statistically significant benefit according to the protocol or statistical analysis plan. Any change to our ongoing trials could cause delays, affect our future expenses, and add uncertainty to our commercialization efforts, as well as to affect the likelihood of the successful completion of clinical development of ivonescimab. Accordingly, readers should not place undue reliance on forward-looking statements or information. In addition, any forward-looking statements included in this presentation represent the Company's views only as of the date of this release and should not be relied upon as representing the Company's views as of any subsequent date. The Company specifically disclaims any obligation to update any forward-looking statements included in this presentation. Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Summit Therapeutics and the Summit Therapeutics logo are trademarks of Summit Therapeutics Inc. Copyright 2026, Summit Therapeutics Inc. All Rights Reserved.2 Summit Proprietary Information - Do Not Copy or Distribute ASCO Update Call June 2026

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). 31 May 2026 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 Chen Zhiwei1, Fang Yang2, Yongzhong Luo3, Longhua Sun4, Lin Wu3, Zhengxiang Han5, Yun Fan6, Yanqiu Zhao7, XingYa Li8, Haipeng Xu9, Xiangjiao Meng10, Ying Liu11, Zhiye Zhang12, Hui Luo13, Qin Shi14, Xuelei Ma15, Xuezhen Ma16, Zhongmin Zhang17, Michelle Y. Xia18, Shun Lu1 1Shanghai Chest Hospital, Shanghai, Jiao Tong University, School of Medicine, Shanghai, China; 2Harbin Medical University Cancer Hospital, Harbin, China; 3Hunan Cancer Hospital, Changsha, China; 4The First Affiliated Hospital of Nanchang University, Nanchang, China; 5The Affiliated Hospital of Xuzhou Medical University, Xuzhou, China; 6Zhejiang Cancer Hospital, Hangzhou, China; 7Henan Cancer Hospital, Zhengzhou, China; 8The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China; 9Fujian Provincial Tumor Hospital, Fuzhou, China; 10Shandong Cancer Hospital and Institute, Jinan, China; 11Jilin Cancer Hospital, Changchun, China; 12The First Affiliated Hospital of Henan University of Science and Technology, Luoyang, China; 13Jiangxi Cancer Hospital, Nanchang, China; 14Fuzhou pulmonary hospital of fujian, Fuzhou, China; 15West China Hospital of Sichuan University, Chengdu, China; 16Qingdao Central Hospital, Qingdao, China; 17Linyi People's Hospital, Linyi, China; 18Akeso Biopharma, Inc., Zhongshan, China ASCO 2026 Plenary Session Note: HARMONi-6 is a single region Phase III study conducted in China sponsored by Akeso with data generated and analyzed by Akeso.

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Study Design A multicenter, randomized, double-blind, parallel-controlled phase III study Key Eligibility Criteria • Pathologically confirmed sq-NSCLC • Stage IIIB-IV • No prior systemic therapy • No EGFR mutations or ALK rearrangements • ECOG PS 0 or 1 Tislelizumab (200 mg, Q3W) + Carboplatin (AUC 5, Q3W) + Paclitaxel (175 mg/m2, Q3W) up to 4 cycles Ivonescimab (20 mg/kg, Q3W) up to 24 months Tislelizumab (200 mg, Q3W) up to 24 months N=532 Stratification Factors: • Stage: IIIB/IIIC vs. IV • PD-L1 TPS: ≥1% vs. <1% Endpoints: • Primary endpoint: PFS by IRRC per RECIST v1.1 • Key secondary endpoint: OS • Secondary endpoints: PFS by INV, ORR, DCR, DoR, TTR and safety Abbreviations: ALK, anaplastic lymphoma kinase; ECOG PS, Eastern Cooperative Oncology Group performance score; R, randomization; AUC, area under the curve; Q3W, every three weeks; IRRC, independent radiology review committee; RECIST v1.1, response evaluation criteria in solid tumors version 1.1; PFS, progression-free survival; OS, overall survival; INV, investigator; ORR, overall response rate; DCR, disease control rate; DoR, duration of response; TTR, time to response. Ivonescimab (20 mg/kg, Q3W) + Carboplatin (AUC 5, Q3W) + Paclitaxel (175 mg/m2, Q3W) up to 4 cycles R 1:1 ASCO 2026 Plenary SessionSponsor: Akeso Inc.

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Baseline Characteristics Tislelizumab + chemo (N=266) Ivonescimab + chemo (N=266)Characteristics, n(%) 139 (52.3)135 (50.8)< 65 Age, years 127 (47.7)131 (49.2)≥ 65 238 (89.5)256 (96.2)Male Sex 28 (10.5)10 (3.8)Female 42 (15.8)42 (15.8)0 ECOG PS\* 222 (83.5)224 (84.2)1 37 (13.9)21 (7.9)Never Smoking history 229 (86.1)245 (92.1)Current/Former 20 (7.5)21 (7.9)IIIB/IIIC Disease stage 246 (92.5)245 (92.1)IV 158 (59.4)178 (66.9)Central type Tumor characteristics 44 (16.5)49 (18.4) Major blood vessel encasement 23 (8.6)24 (9.0)With cavity 79 (29.7)86 (32.3)With hemoptysis history 105 (39.5)105 (39.5)<1% PD-L1 TPS 161 (60.5)161 (60.5)≥ 1% 99 (37.2)112 (42.1)1-49% 62 (23.3)49 (18.4)≥ 50% 39 (14.7)42 (15.8)≥3 metastatic sites Metastases sites 45 (16.9)28 (10.5)Liver metastases 17 (6.4)9 (3.4)Brain metastases \*Two patients' ECOG PS were missing in the tislelizumab plus chemotherapy arm. ASCO 2026 Plenary Session

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Ivonescimab with chemotherapy significantly improved OS Overall Survival (interim analysis) Tislelizumab + chemo (N=266) Ivonescimab + chemo (N=266) 23.69 (20.11, NE) 27.89 (27.89, NE) mOS, months (95% CI) 0.66 (0.50, 0.87) Stratified HR (95% CI) 0.0017p-value Abbreviation: mOS, median overall survival; NE, not estimable; HR, hazard ratio; CI, confidence interval OS significance boundary: 0.0049 The median OS in the ivonescimab group would have not been reached without the last single event Ivonescimab +Chemo Tislelizumab +Chemo No. at risk (censored) 266(0) 266(0) 252(0) 257(0) 238(0) 238(0) 224(0) 211(0) 202(8) 186(6) 152(46) 142(36) 119(73) 113(55) 85(100) 80(77) 49(135) 43(107) 15(168) 12(136) 0(182) 0(146) • Data cutoff date: Feb 27, 2026 • Median Follow-up: 21.36 months ASCO 2026 Plenary Session 78.9% 72.2% 64.7% 48.6%

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). OS benefit was consistent across key subgroups Subgroup Analysis of Overall Survival Median OS and HR will not be reported for subgroups with fewer than 10 events Hazard ratio (95% CI) Tislelizumab+chemoIvonescimab+chemo Characteristic Events/Number of subjectsEvents/Number of subjects Hazard ratio (95% CI)ASCO 2026 Plenary Session 84/266 31/135 53/131 79/256 5/10 10/42 74/224 7/21 77/245 39/105 45/161 32/112 13/49 18/42 66/224 11/28 73/238 2/9 82/257 Brain metastases Yes No Liver metastases Yes No ≥3 metastases sites Yes No PD-L1 TPS <1% ≥1% 1 – 49% ≥50% Disease Stage IIIB/IIIC IV ECOG PS 0 1 Sex Male Female Overall Age, Years <65 ≥65 120/266 63/139 57/127 110/238 10/28 21/42 99/222 8/20 112/246 56/105 64/161 43/99 21/62 28/39 92/227 25/45 95/221 12/17 108/249 0.66 (0.50, 0.87) 0.43 (0.28, 0.67) 0.93 (0.64, 1.36) 0.63 (0.47, 0.84) 0.47 (0.22, 0.99) 0.71 (0.52, 0.96) 0.63 (0.48, 0.86) 0.64 (0.43, 0.96) 0.68 (0.46, 0.99) 0.67 (0.42, 1.05) 0.64 (0.32, 1.31) 0.47 (0.26, 0.85) 0.70 (0.51, 0.97) 0.69 (0.34, 1.41) 0.68 (0.50, 0.92) 0.71 (0.53, 0.95)

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Ivonescimab with chemotherapy showed consistent OS improvement across subgroups stratified by PD-L1 expression levels Overall survival by PD-L1 expression levels ASCO 2026 Plenary Session Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). • The subgroup analysis was descriptive and not formally powered

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Safety Summary b Tislelizumab + chemo (N=265) Ivonescimab + chemo (N=266) 263 (99.2)264 (99.2)TRAE 156 (58.9)184 (69.2)Grade ≥ 3 TRAE 91 (34.3)110 (41.4)Serious TRAE 12 (4.5)14 (5.3)Leading to ivonescimab or tislelizumab discontinuation 11 (4.2)10 (3.8)Leading to death 36 (14)34 (14)Grade ≥ 3 irAE# Abbreviation: TRAE, treatment-related adverse events. Ivonescimab plus chemotherapy showed a manageable safety profile in squamous NSCLC ASCO 2026 Plenary Session • Data are n (%) • # immune-related adverse events were assessed by investigators

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Possibly VEGF-related adverse events Ivonescimab exhibited similar irAEs to tislelizumab. Abbreviation: VEGF, vascular endothelial growth factor; AEs, adverse events; irAEs, immune-related adverse events. # AE terms were grouped terms. Possibly VEGF-related AEs occurred more frequently in the ivonescimab arm, most of which were Grade 1-2. Tislelizumab + chemo (N=265)Ivonescimab + chemo (N=266)Possibly VEGF- Related AEs# Grade ≥3Grade 2Grade 1Any GradeGrade ≥3Grade 2Grade 1Any Grade 08 (3.0)26 (9.8)34 (12.8)18 (6.8)60 (22.6)35 (13.2)113 (42.5)Proteinuria 2 (0.8)6 (2.3)24 (9.1)32 (12.1)7 (2.6)20 (7.5)39 (14.7)66 (24.8)Haemorrhage 5 (1.9)7 (2.6)3 (1.1)15 (5.7)10 (3.8)22 (8.3)7 (2.6)39 (14.7)Hypertension 00003 (1.1)01 (0.4)4 (1.5) Arterial thromboembolism 1 (0.4)2 (0.8)03 (1.1)02 (0.8)02 (0.8) Venous thromboembolism 000001 (0.4)01 (0.4)Fistula • # AE terms were grouped terms • Data are n (%) ASCO 2026 Plenary Session

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Conclusions • Ivonescimab with chemotherapy significantly improved OS in advanced squamous NSCLC first- line treatment compared with tislelizumab with chemotherapy • mOS: 27.89 vs. 23.69, HR=0.66 (95%CI: 0.50, 0.87), p=0.0017 • Ivonescimab with chemotherapy showed comparable safety profile to tislelizumab with chemotherapy • ≥ G3 TRAE: 69.2% vs. 58.9% • Similar rates of AEs leading to discontinuation or death between the two arms ASCO 2026 Plenary Session • HARMONi-6 supports adoption of ivonescimab with chemotherapy as a new standard for patients with advanced squamous NSCLC in first-line treatment in China • A global phase III study (HARMONi-3, NCT05899608) is underway

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Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Favors Ivonescimab+chemo Favors Tislelizumab+chemo Refresh from ESMO 2025 Presentation: Subgroup Analysis of PFS by IRRC (Oct 2025 Presentation) • PFS benefit favored ivonescimab across all key subgroups. • Observed important baseline imbalances in the older patient subgroup (Age ≥65), such as target lesion size, brain metastases. After adjusting for these covariates, the adjusted HR for Age ≥65 was 0.69. If the number of events at a level of a subgroup is less than 10, the median PFS and hazard ratio will not be provided. ESMO 2025 Presidential Symposium Shun Lu Previously Presented PFS Data – Oct 2025 (ESMO 2025 and Chen, et. al., The Lancet)

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Ivonescimab: The Numbers Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Positive Phase III Readouts to Date The only in-class Phase III Readouts Phase III Trials in Multiple Tumor Types1 Patients Dosed in All Clinical Trials2 Indications Approved in China by the NMPA 2 Chinese Approvals3 Patients Dosed Commercially in China Total Ivonescimab Trials Sponsored by Summit, Akeso, or GORTEC Total Trials Involving Ivonescimab on clinicaltrials.gov 4 Phase III Trials with Positive Results 15 Phase III Trials1 >4,000 Trial Patients >70,000 Commercial Patients in China3 47 Sponsored Trials1 155 Total Trials1 Anti-VEGF Anti-PD-1 Most Advanced, First-in-Class, PD-1/VEGF Bispecific Antibody Abbreviations: PD-1=programmed cell death protein 1; VEGF=vascular endothelial growth factor; NMPA = National Medical Products Administration (China) References: 1. Total sponsored (by Summit, Akeso, or GORTEC) clinical trials as of May 20, 2026, via clinicaltrials.gov or public announcement; 2. Data on File 56, 57. Summit Therapeutics Inc. 3. Akeso March 27, 2026 press release, Akeso Reports Full-Year 2025 Financial Results

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Ivonescimab Development Plan Ivo esci ab evelop e t: HARMONi Summit Pipeline References: 1. In Summit license territories, Data on File 55. Summit Therapeutics Inc. Supported = at a minimum, a notification of support communicated to PI; 2. Publications available at smmttx.com, Accessed on May 31, 2026. Abbreviations: 1L=first-line; 2L=second-line; ADC=antibody drug conjugate; Chemo=chemotherapy; CRC=colorectal cancer; EGFRm+=epidermal growth factor receptor mutant positive; ISTs=Investigator Sponsored Trials; NSCLC=non-small-cell lung cancer; PDAC=pancreatic ductal adenocarcinoma; HNSCC=head and neck squamous cell carcinoma; PD-L1=programmed cell death-ligand 1; RAS=renin-angiotensin system; RASi=RAS inhibitor; RAS(ON)i=RAS inhibitor to RAS proteins in ON state (revmed.com/science, Accessed May 31, 2026); SCLC=small cell lung cancer; incl.=including; vs.=versus. Reference: ClinicalTrials.gov Collaborations GORTEC: enrolling Ph3 ILLUMINE Study: HNSCC RevMed: enrolling Novel RAS(ON)i: NSCLC, PDAC, CRC Future collaboration with ADC >60 ISTs1 22 Currently Enrolling 5 via MD Anderson Collaboration Ivonescimab Publications2 ll r ti s >65 ISTs Supported1 >50 Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). EGFRm NSCLC post-TKI Ivonescimab + chemo vs. placebo + chemo Enrollment Complete EnrollingEnrollingSQ: enrollment complete nSQ: screening complete 1L CRC Ivonescimab + chemo vs. bevacizumab + chemo 1L NSCLC: PD-L1 High Ivonescimab vs. pembrolizumab 1L NSCLC Ivonescimab + chemo vs. pembrolizumab + chemo

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Best Change in Tumor from Baseline Summary of Efficacy & Safety Ivonescimab + FOLFOX 10 mg/kg (n=24) Ivonescimab + FOLFOX 20 mg/kg (n=24) 70.8%70.8%ORR, % 100%100%DCR, % 41.5%79.1%Landmark 9-month DoR Landmark 9-month PFS 70.1%76.1%9-month PFS (44.9, 85.4)(51.7, 89.4)(95% CI), % Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA). Phase II CRC ORR 70.8%, DCR 100% Ivonescimab plus Chemotherapy in 1L CRC DCR, disease control rate; PFS, progression free survival

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16 The Next Exciting Steps for Summit & Ivonescimab 1H26 HARMONi-3 nSQ: Completed screening, patient enrollment expected to complete 2H26 HARMONi-3 SQ: PFS, interim OS data readout expected HARMONi: BLA PDUFA Date in November 1H27 HARMONi-3 nSQ: PFS data readout expected Anti-VEGF Anti-PD-1 Abbreviations: BLA=Biologics License Application; EGFRm+=epidermal growth factor receptor mutant positive; NSCLC=non-small-cell lung cancer; nSQ=non-squamous; OS=overall survival; PD-1=programmed cell death protein 1; PD- L1=programmed cell death-ligand 1; PFS=progression-free survival; SQ=squamous; VEGF=vascular endothelial growth factor; TKI=tyrosine kinase inhibitor. Continuing Acceleration of Clinical Development Ivonescimab is an investigational therapy not presently approved by any regulatory authority other than China's National Medical Products Administration (NMPA).

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2028 PD-(L)1 Addressable Market2 Approved Anti PD-(L)1 & Anti-VEGF Therapies Approved Anti PD-(L)1 Therapies Approved Anti-VEGF Therapies 50+ Approved Indications for PD-(L)1 & VEGF Therapies1 $90B+ 2028 VEGF Addressable Market2 $20B+ Where Summit is currently exploring globally 1. KEYTRUDA® USPI, OPDIVO® USPI, LIBTAYO® USPI, IMFINZI® USPI, BAVENCIO® USPI, JEMPERLI® USPI, TECENTRIQ® USPI, ZYNYZ® USPI, AVASTIN® USPI, CYRAMZA® USPI, LENVIMA® USPI, INLYTA® USPI, SUTENT® USPI. 2. TD Cowen and IQVIA, estimates. Abbreviations: EGFRm=epidermal growth factor receptor mutation; NSCLC=non-small-cell lung cancer; PD-1=programmed cell death protein 1; PD-L1=programmed cell death-ligand 1; TNBC=triple-negative breast cancer; VEGF=vascular endothelial growth factor Ivonescimab Revenue Potential by 2033 $15B+

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