Ivonescimab Monotherapy Demonstrates a Statistically Significant & Clinically Meaningful Benefit Compared to Pembrolizumab Monotherapy in PD-L1-Positive Advanced NSCLC in Akeso’s HARMONi-2 Study Conducted in China

New HARMONi-2 overall survival data strengthen ivonescimab’s profile as Summit advances a broad late-stage program and awaits a U.S. FDA decision.

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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 = intention-to-treat 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 (IRRC), when compared to pembrolizumab monotherapy, achieving a hazard ratio (HR) of 0.51 (95% CI: 0.38, 0.69; p<0.0001).¹

“HARMONi-2 is the fourth Phase III study of ivonescimab to demonstrate statistically significant improvements for both overall survival and progression-free survival in head-to-head comparisons against standard-of-care regimens,” said Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit Therapeutics. “Demonstrating a survival benefit against pembrolizumab monotherapy in this setting further strengthens our conviction that ivonescimab has the potential to advance treatment beyond PD-1 blockade alone and define what a next-generation immuno-oncology therapy can deliver for patients with lung cancer.”

“Positive overall survival results in HARMONi-2 mark a pivotal moment for ivonescimab and underscore the promise of its differentiated PD-1 / VEGF bispecific approach,” said Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit Therapeutics. “These data build on the study’s previously reported progression-free survival benefit, while further informing our confidence in the broader ivonescimab development program, including HARMONi-7, our ongoing global Phase III study evaluating ivonescimab monotherapy against pembrolizumab monotherapy in patients with PD-L1 high-expressing metastatic non-small cell lung cancer.”

Global Phase III HARMONi-7 Study
Based on the primary analysis results of HARMONi-2, Summit initiated the global HARMONi-7 study (NCT06767514) in early 2025. HARMONi-7 is a randomized, double-blind, multi-regional Phase III clinical trial evaluating ivonescimab monotherapy to pembrolizumab monotherapy in the first-line treatment of patients with metastatic NSCLC whose tumors have high PD-L1 expression (PD-L1 Score > 50%). The study is currently recruiting, with a target enrollment of 780 patients globally. The co-primary endpoints of HARMONi-7 are PFS and OS.

The HARMONi-2 study is being conducted by Akeso in China, where ivonescimab is approved and commercially available for indications in 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 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 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 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 colorectal cancer (CRC) in the fourth quarter of 2025 by initiating enrollment in HARMONi-GI3. In 2026, Summit announced initiation of HARMONi-GU1, a Phase II/III study in urothelial carcinoma (bladder cancer) with global clinical trial site activations planned to begin by the fourth quarter of 2026.

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 filing 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 first-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 first-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 first-line unresectable metastatic CRC.

HARMONi-GU1 is a Phase II/III clinical trial evaluating 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 (la/mUC).

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.

Five Phase III ivonescimab clinical trials have read out to date, all five with positive data. Four of these five studies are in NSCLC, and one is in biliary tract cancer (BTC). In addition to Summit’s positive HARMONi study, Akeso has had positive read-outs in three single-region (China), randomized Phase III clinical trials in NSCLC, HARMONi-A, HARMONi-2, and HARMONi-6, including a statistically significant overall survival benefit in all three studies. Akeso has also reported a statistically significant OS benefit in the single-region (China), randomized Phase III HARMONi-GI1 trial in advanced BTC.

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.

HARMONi-GI1 is a Phase III clinical trial evaluating ivonescimab in combination with chemotherapy compared with durvalumab plus chemotherapy as a first-line treatment for patients with advanced BTC.

Akeso is actively conducting additional Phase III clinical studies in settings outside of NSCLC and biliary-tract cancer, including 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 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 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 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 press release represent the Company’s views only as of the date of this release and should not be relied upon as representing the Company’s views as of any subsequent date. The Company specifically disclaims any obligation to update any forward-looking statements included in this press release.

References:

1. Xiong A, Wang L, Chen J, Wu L, Liu B, Yao J, et al. Ivonescimab versus pembrolizumab for PD-L1-positive non-small cell lung cancer (HARMONi-2): a randomised, double-blind, phase 3 study in China. Lancet. 2025;405(10481):839-849. doi:10.1016/S0140-6736(24)02722-3.

Summit Therapeutics and the Summit Therapeutics logo are registered trademarks of Summit Therapeutics Inc. and/or its affiliates. Copyright 2026, Summit Therapeutics Inc. All Rights Reserved.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260913549808/en/

Summit Therapeutics’ Media & Investor Contacts:
Nathan LiaBraaten
Senior Director, Investor Relations

Tracy Jones
Director, Media & Public Relations

investors@smmttx.com
media@smmttx.com

Source: Summit Therapeutics

Key Terms

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A hazard ratio is a way scientists compare the chance of something happening over time between two groups, like patients taking different medicines. If the ratio is high, it means one group is more likely to experience the event sooner or more often, which helps determine how effective a treatment is or how risky a situation might be.

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Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.

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A bispecific antibody is a specially designed protein that can attach to two different targets at the same time. Think of it as a custom-made connector that brings two things together—such as a disease cell and an immune system component—helping the body fight illnesses more effectively. For investors, understanding bispecific antibodies is important because they represent innovative therapies that could lead to new treatments and potentially lucrative market opportunities.

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