Summit Therapeutics SMMT stock climbed 17.3% on Thursday after its Chinese partner Akeso reported positive overall survival (OS) results for ivonescimab in a head-to-head phase III study against Merck's MRK blockbuster oncology drug, Keytruda (pembrolizumab), in certain patients with non-small cell lung cancer (NSCLC). The data provided fresh clinical validation for SMMT's lead oncology candidate and increased investor focus on the drug's potential in the United States and other licensed markets.

Summit Therapeutics is developing ivonescimab in collaboration with Akeso. The company acquired an exclusive license from Akeso in 2022 to develop and market the drug in the United States, Canada, Europe and Japan. SMMT later amended this collaboration agreement in June 2024, expanding its licensing deal to cover Latin America (including Mexico and all countries in Central America, South America and the Caribbean), the Middle East and Africa. Akeso retains the rights to market the drug in China, where the drug is approved for three NSCLC indications. Ivonescimab remains investigational in Summit's licensed territories.

Akeso's phase III HARMONi-2 study evaluated ivonescimab monotherapy against MRK's Keytruda monotherapy in patients with locally advanced or metastatic NSCLC whose tumors have positive PD-L1 expression. In the latest preplanned analysis, Akeso reported that ivonescimab monotherapy achieved a statistically significant improvement in OS versus Keytruda monotherapy, meeting a key secondary endpoint of the HARMONi-2 study. The China-based study had previously demonstrated a statistically significant progression-free survival (PFS) benefit, with an HR of 0.51, across multiple clinical subgroups. Additional details are expected at an upcoming medical conference.

The HARMONi-2 result is particularly relevant because Summit Therapeutics is conducting the global Phase III HARMONi-7 study, including sites in the United States, to evaluate ivonescimab monotherapy versus Merck's Keytruda monotherapy in patients with previously untreated metastatic NSCLC and high PD-L1 expression. The study is designed to assess both PFS and OS and is currently enrolling patients.

Year to date, SMMT shares have lost 2% compared with the industry's 0.9% decline.

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SMMT's Progress With Ivonescimab

Summit Therapeutics is currently pursuing U.S. regulatory approval for ivonescimab plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous NSCLC who had progressed after treatment with an EGFR-TKI. The submission is based on positive results from the phase III HARMONi study, which evaluated the combination for this indication. The study met one of its two primary endpoints — PFS. Although the study did not meet the OS endpoint, which the FDA had previously identified as a key requirement for filing, the data showed a favorable trend toward OS. The agency is expected to make a decision by Nov. 14, 2026, potentially providing SMMT with an additional regulatory milestone for the candidate in the United States.