Summit Therapeutics drug shows 30.8-month OS in NSCLC
Rhea-AI Filing Summary
Summit Therapeutics Inc. (SMMT) reported updated overall survival data for ivonescimab from the global Phase III HARMONi trial in EGFR‑mutated non-small cell lung cancer, showing a hazard ratio of 0.76 (95% CI: 0.61–0.95; nominal p=0.0151) for overall survival in the global intention‑to‑treat population versus placebo plus chemotherapy at the June 2026 data cut. Median overall survival remained 16.8 months for ivonescimab plus chemotherapy and 14.0 months for placebo plus chemotherapy across data cuts, while western patients showed convergence of benefit with a hazard ratio of 0.76 (95% CI: 0.52–1.10) and median overall survival of 17.5 vs 14.0 months at the latest analysis. Safety in HARMONi continued to be described as acceptable and manageable with no new signals. Summit highlighted that its Biologics License Application for ivonescimab in this setting has an FDA PDUFA goal action date of November 14, 2026.
Separately, Akeso’s China-based Phase III HARMONi-2 trial in NSCLC showed ivonescimab monotherapy improved median overall survival to 30.8 months versus 22.6 months with pembrolizumab (hazard ratio 0.73, 95% CI: 0.57–0.95; p=0.009), with consistent benefits in key PD‑L1 and histology subgroups and a safety profile characterized as acceptable and manageable.
Positive
- Global HARMONi OS benefit strengthened: June 2026 analysis showed an overall survival hazard ratio of 0.76 (95% CI: 0.61–0.95; nominal p=0.0151) for ivonescimab plus chemotherapy versus placebo plus chemotherapy.
- Western patient survival improvement aligns globally: western subgroup hazard ratio reached 0.76 (95% CI: 0.52–1.10) with median OS of 17.5 vs 14.0 months, reinforcing regional consistency.
- HARMONi-2 showed significant OS advantage over pembrolizumab: ivonescimab monotherapy achieved median OS of 30.8 vs 22.6 months and a hazard ratio of 0.73 (95% CI: 0.57–0.95; p=0.009) in the ITT population.
- Regulatory timeline defined: the Biologics License Application for ivonescimab based on HARMONi has an FDA PDUFA goal action date of November 14, 2026, providing a clear decision milestone.
Negative
- None.
Insights
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8-K Event Classification
2 items: 8.01, 9.01
2 items
Item 8.01
Other Events
Other
Voluntary disclosure of events the company deems important to shareholders but not covered by other items.
Item 9.01
Financial Statements and Exhibits
Exhibits
Financial statements, pro forma financial information, or exhibit attachments filed with this report.
Key Figures
HARMONi ITT OS hazard ratio (June 2026): 0.76 (95% CI: 0.61–0.95; nominal p=0.0151)
HARMONi median overall survival: 16.8 months vs 14.0 months
Western subgroup median OS (June 2026): 17.5 months vs 14.0 months
+5 more
8 metrics
HARMONi ITT OS hazard ratio (June 2026)
0.76 (95% CI: 0.61–0.95; nominal p=0.0151)
Ivonescimab plus chemotherapy vs placebo plus chemotherapy in global ITT NSCLC population
HARMONi median overall survival
16.8 months vs 14.0 months
Ivonescimab plus chemotherapy vs placebo plus chemotherapy across data cuts
Western subgroup median OS (June 2026)
17.5 months vs 14.0 months
Ivonescimab plus chemotherapy vs placebo plus chemotherapy in western HARMONi patients
HARMONi-2 median overall survival
30.8 months vs 22.6 months
Ivonescimab vs pembrolizumab monotherapy in ITT NSCLC population (n=398)
HARMONi-2 OS hazard ratio
0.73 (95% CI: 0.57–0.95; p=0.009)
Ivonescimab vs pembrolizumab in HARMONi-2 interim OS analysis
PDUFA goal action date
November 14, 2026
FDA review of ivonescimab Biologics License Application based on HARMONi
HARMONi-2 36-month OS rates
45.0% vs 33.1%
Kaplan–Meier overall survival rates for ivonescimab vs pembrolizumab at 36 months
Serious treatment-related adverse events (HARMONi-2)
29.9% vs 21.6%
Ivonescimab (59 of 198) vs pembrolizumab (43 of 200) patients
Key Terms
overall survival, hazard ratio, intention-to-treat population, Biologics License Application, +2 more
6 terms
overall survival medical
"updated overall survival (OS) results from the global Phase III HARMONi"
Overall survival is the average or median length of time patients remain alive after starting a treatment or entering a clinical study, measured regardless of cause of death. Investors care because it is a clear, hard measure of a therapy’s real-world benefit — like timing how long a new battery actually runs — and strong improvements in overall survival can drive regulatory approval, market adoption and revenue potential.
hazard ratio medical
"showed a positive trend without achieving a statistically significant benefit with a hazard ratio of 0.79"
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.
intention-to-treat population medical
"OS hazard ratio of 0.76 (95% CI: 0.61 – 0.95; nominal p=0.0151) in the global intention-to-treat (ITT) population"
Biologics License Application regulatory
"Biologics License Application (BLA) with the U.S. Food and Drug Administration"
A biologics license application is a formal request submitted to regulatory authorities seeking approval to market a new biological medicine, such as vaccines or treatments made from living organisms. It is a comprehensive review process that evaluates the safety, effectiveness, and manufacturing quality of the product. For investors, receiving approval signals that a biological therapy can be sold to the public, potentially leading to revenue growth and market success.
Prescription Drug User Fee Act regulatory
"has a Prescription Drug User Fee Act (PDUFA) goal action date of November 14, 2026"
A federal program that lets drug makers pay fees to the U.S. regulator to fund and speed up the review of new medicines and label changes. Investors care because it affects how quickly a drug can move from testing to market and how predictable approval timelines and regulatory interactions are — like buying a faster lane at a busy checkpoint that can reduce uncertainty about a product’s commercial timing.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What did Summit Therapeutics (SMMT) report from the Phase III HARMONi trial?
Summit reported updated overall survival data showing ivonescimab plus chemotherapy achieved a hazard ratio of 0.76 (95% CI: 0.61–0.95; nominal p=0.0151) versus placebo plus chemotherapy, with median OS of 16.8 vs 14.0 months in the global intention‑to‑treat population.
How did ivonescimab perform in western patients in HARMONi?
In western patients, ivonescimab plus chemotherapy showed a hazard ratio of 0.76 (95% CI: 0.52–1.10) versus placebo plus chemotherapy, with median overall survival of 17.5 months compared to 14.0 months at the June 2026 data cut.
What were the key Phase III HARMONi-2 results highlighted by SMMT?
HARMONi-2 showed ivonescimab monotherapy improved median overall survival to 30.8 months versus 22.6 months with pembrolizumab, with an overall survival hazard ratio of 0.73 (95% CI: 0.57–0.95; p=0.009) in the 398‑patient intention‑to‑treat population.
Were there any new safety findings for ivonescimab in these studies?
Summit and Akeso stated that ivonescimab maintained an acceptable and manageable safety profile in both HARMONi and HARMONi-2, with no additional safety signals observed in the latest data cuts compared with prior Phase III data.
What is the FDA review timeline for ivonescimab based on HARMONi?
Summit’s Biologics License Application for ivonescimab in EGFR‑mutated NSCLC based on HARMONi has a Prescription Drug User Fee Act (PDUFA) goal action date of November 14, 2026, following FDA acceptance of the filing in January 2026.
How many patients have been treated with ivonescimab to date?
Summit reported that over 4,000 patients have received ivonescimab in clinical studies globally and over 70,000 patients have been treated in a commercial setting in China, according to information noted by Akeso.
In which additional cancers is ivonescimab being studied according to SMMT?
Ivonescimab is being studied in multiple Phase III trials beyond EGFR‑mutated NSCLC, including first-line metastatic NSCLC, colorectal cancer, biliary tract cancer, urothelial carcinoma, and other solid tumors such as triple‑negative breast cancer and head and neck squamous cell carcinoma.
AI-generated analysis. How Rhea-AI works. Not financial advice.
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): September 15, 2026
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Registrant’s Telephone Number, Including Area Code: (305) 203-2034
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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):
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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).
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Item 8.01 | Other Events. | ||||
On September 15, 2026, Summit Therapeutics Inc. (the "Company") issued a press release announcing that updated overall survival results from the global Phase III HARMONi clinical trial were presented today at the International Association for the Study of Lung Cancer 2026 World Conference on Lung Cancer (“WCLC 2026”). The press release also noted data from the randomized, double-blind Phase III HARMONi-2 trial presented by the Company's partner, Akeso Inc., at WCLC 2026.
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.
| Item 9.01 | Financial Statements and Exhibits. | ||||
(d) Exhibits
Exhibit Number | Description | ||||
| 99.1 | Press Release, dated September 15, 2026 | ||||
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) | ||||
SIGNATURE
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, hereunto duly authorized.
| SUMMIT THERAPEUTICS INC. | ||||||||
| Date: September 15, 2026 | By: | /s/ Manmeet S. Soni | ||||||
| Chief Operating Officer, Chief Financial Officer and Director | ||||||||
| (Principal Financial Officer) | ||||||||
Updated HARMONi Data Presented at WCLC 2026 Demonstrate Consistent Overall Survival Results with Ivonescimab Plus Chemotherapy in Western and Asian Patients 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, Florida, September 15, 2026 – 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% CI: 0.62 – 1.01; p=0.057) 0.78 (95% CI: 0.62 – 0.98; nominal p=0.0332) 0.76 (95% CI: 0.61 – 0.95; nominal p=0.0151) DCO = data cut-off; ITT = intention-to-treat population; mos = months; chemo = chemotherapy *DCO for Asian patients was Apr 2025 for both Sept 2025 and June 2026 analyses With longer follow-up, western patients replicated the survival improvement seen in Asian patients, further reinforcing the regional consistency of the efficacy results observed in the global HARMONi study. DCO = data cut-off; ITT = intention-to-treat population; mos = months; chemo = chemotherapy In this most recent analysis, ivonescimab continued to demonstrate an acceptable and manageable safety profile that was consistent with previous Phase III data of ivonescimab plus chemotherapy. No additional safety signals were noted in this latest HARMONi data cut. “The updated HARMONi overall survival analysis presented at WCLC 2026 provides important additional evidence of the consistency of ivonescimab’s clinical profile across patient populations, with western patients showing consistent survival improvement to what was observed in Asian patients,” stated Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit. “Together with the continued acceptable and manageable Western Subgroup of Overall Survival Analyses at Each Data Cut-Off DCO: Apr 2025 DCO: Sept 2025 DCO: June 2026 Ivonescimab + Chemo Placebo + Chemo Ivonescimab + Chemo Placebo + Chemo Ivonescimab + Chemo Placebo + Chemo (n=83) (n=82) (n=83) (n=82) (n=83) (n=82) Median OS, Western Patients Not Reached 14.0 mos 17.0 mos 14.0 mos 17.5 mos 14.0 mos Hazard Ratio, Western Patients 0.98 (95% CI: 0.55 – 1.73) 0.84 (95% CI: 0.53 – 1.32) 0.76 (95% CI: 0.52 – 1.10) Median follow-up, Western Patients 9.2 mos 13.7 mos 23.2 mos
safety profile, these data reinforce our confidence in the HARMONi results as we work toward the potential approval of ivonescimab in the U.S.” “What continues to distinguish ivonescimab is not only the strength of these HARMONi results, but the expanding clinical data sets emerging across studies and tumor types, including recent positive results from HARMONi-2 and HARMONi-GI1 in biliary tract cancer,” added Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit. “Together, these data reinforce our belief in the potential breadth of ivonescimab’s differentiated bispecific design as an important new therapeutic approach in oncology, beginning with EGFR-mutated non-small cell lung cancer and extending across our broader ambition to address serious needs in solid tumors where patients urgently need better options.” 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. HARMONi-2 Detailed OS Efficacy and Safety Results Previously, key findings from the HARMONi-2 primary OS analysis were announced by Summit’s partner, Akeso Inc. Today, the full detailed results were presented at WCLC 2026, with highlights provided below. 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 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) Median Follow-up: 36.0 mos Ivonescimab (n=198) Pembrolizumab (n=200) Median OS 30.8 mos (95% CI: 25.4, 37.8) 22.6 mos (95% CI: 17.8, 26.5) OS Stratified HR 0.73 (95% CI: 0.57, 0.95; p=0.009) 24-Month KM OS Rate 57.9% 48.0% 36-Month KM OS Rate 45.0% 33.1% ITT = intention-to-treat population; mos = months; CI = confidence interval, KM= Kaplan Meier method HARMONi-2 Subgroup Analyses Descriptive, not formally powered Ivonescimab vs. Pembrolizumab
PD-L1 High (PD-L1 Score ≥50%) n=168 HR = 0.58 (95% CI: 0.38, 0.89) Median OS: NR vs. 23.2 mos PD-L1 Low (PD-L1 Score 1-49%) n=230 HR = 0.85 (95% CI: 0.61, 1.18) Median OS: 28.5 mos vs. 22.1 mos Squamous Histology n=181 HR = 0.65 (95% CI: 0.45, 0.95) Median OS: 30.5 mos vs. 19.3 mos Non-Squamous Histology n=217 HR = 0.79 (95% CI: 0.55, 1.14) Median OS: 33.6 mos vs. 25.6 mos Age <65 n=182 HR = 0.75 (95% CI: 0.51, 1.11) Median OS: 32.8 mos vs. 25.0 mos Age ≥65 n=216 HR = 0.72 (95% CI: 0.51, 1.01) Median OS: 30.2 mos vs. 22.1 mos Male n=333 HR = 0.74 (95% CI: 0.56, 0.98) Female n=65 HR = 0.69 (95% CI: 0.38, 1.25) NR = not reached; mos = months; CI=confidence interval; n = number 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 Median follow-up: 36.0 mos Ivonescimab (n=198) Pembrolizumab (n=200) Serious TRAEs, n (%) 59 (29.9) 43 (21.6) TRAEs Leading to Discontinuation, n (%) 8 (4.1) 10 (5.0) TRAEs Leading to Death, n (%) 1 (0.5) 3 (1.5) TRAEs = treatment-related adverse events; n = number; mos = months 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, HARMONi-A, HARMONi-2, and HARMONi-6, for ivonescimab in NSCLC, including a statistically significant overall survival benefit in all three studies from China. 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. Summit Therapeutics’ Media & Investor Contacts: Nathan LiaBraaten Senior Director, Investor Relations Tracy Jones Director, Media & Public Relations
investors@smmttx.com media@smmttx.com 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.