Akeso-Summit Lung Cancer Drug Reduces Death Risk by 34% in China Trial, Global Study Underway
An experimental lung cancer drug developed by Akeso and Summit Therapeutics reduced the risk of death by 34% in a closely watched late-stage trial, according to results released Sunday. When combined with chemotherapy, the drug extended survival for patients with squamous non-small-cell lung cancer by a median of four months compared to the standard combination of immunotherapy and chemotherapy, a statistically significant outcome.
Trial Results and Clinical Significance
The Phase 3 trial, named Harmoni-6, was conducted exclusively in China and will be presented at the American Society of Clinical Oncology’s annual meeting. Ivonescimab combined with chemotherapy kept patients alive for a median of 27.9 months, versus 23.7 months for those receiving a standalone PD-1 inhibitor plus chemotherapy. The four-month improvement in overall survival was statistically significant.
"The fact that it shows an improvement in overall survival in a difficult-to-treat patient population is very encouraging," said Dr. Suresh Ramalingam, executive director of the Winship Cancer Institute of Emory University. "I'm mindful of the fact that this trial was done exclusively in China, and that brings up the question of how do these data apply to patient populations outside of China, and that will require future investigations."
Dr. Deborah Dorosh questioned the clinical significance, stating: "It's not clear how meaningful that is."
Drug Mechanism and Industry Debate
Ivonescimab is a bispecific antibody targeting two proteins: PD-1, which helps cancer cells evade the immune system (similar to Merck's Keytruda), and VEGF, which promotes blood vessel growth that can help cancer cells thrive (similar to Roche's Avastin). Previous studies demonstrated ivonescimab's ability to control tumor growth, known as progression-free survival, but that endpoint alone is typically insufficient for U.S. Food and Drug Administration approval, which requires evidence that drugs extend patient survival. Older VEGF inhibitors that effectively controlled tumors struggled to improve survival, raising doubts about whether ivonescimab's early promise would hold.
The drug has sparked intense debate in oncology and investment circles. Some analysts view ivonescimab and similar bispecific antibodies as potential successors to Merck's Keytruda, while others caution it may disappoint like earlier promising approaches targeting TIGIT, an immune receptor.
Summit Therapeutics Stock Performance
The competing narratives are reflected in the stock price of U.S.-based Summit Therapeutics, which licensed ivonescimab rights outside of China from Akeso. Summit shares have surged nearly 600% over the two years since the company reported that ivonescimab more effectively controlled tumors than Keytruda in a separate China trial. However, the stock has declined over the past month amid concerns the drug may prove less effective in a global patient population. A global Phase 3 study is currently ongoing.
Market Context
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- Date: May 31, 2026