Summit Therapeutics Inc. (NASDAQ: SMMT) announced that its partner Akeso Inc. reported positive topline results from the Phase III HARMONi-GI1 study evaluating ivonescimab plus chemotherapy against durvalumab plus chemotherapy as a first-line treatment for patients with advanced biliary tract cancer (BTC).

According to the press release, the study met its primary endpoint of overall survival (OS) at a pre-specified interim analysis, with the ivonescimab-based regimen achieving statistically significant superiority over the durvalumab-based regimen. The trial also met key secondary endpoints of progression-free survival and objective response rate.

HARMONi-GI1 is a single-region, multi-center trial conducted and sponsored by Akeso in China. All data were generated, managed, and analyzed by Akeso. Akeso claims the study is the first known Phase III trial in advanced BTC to demonstrate OS superiority versus an anti-PD-(L)1 plus chemotherapy regimen.

Detailed safety and efficacy data are expected to be presented at a future medical congress and published in a peer-reviewed journal. No specific numerical results were disclosed in the announcement.

Ivonescimab is a bispecific antibody targeting both PD-1 and VEGF. The drug is approved in China for non-small cell lung cancer indications but remains investigational in Summit's license territories, which include the United States and Europe.

Summit previously submitted a Biologics License Application to the U.S. Food and Drug Administration for ivonescimab in a different indication, with a goal PDUFA date of November 14, 2026. Five Phase III ivonescimab trials have reported results to date, all with outcomes described as positive by the companies involved.