Summit Therapeutics Inc. filed a Form 8-K with the SEC on August 26, 2026, reporting that partner Akeso, Inc. announced positive topline results from the Phase III HARMONi-GI1 study evaluating ivonescimab plus chemotherapy as a first-line treatment for advanced biliary tract cancer.

Key Highlights

  • Primary endpoint met: At a pre-specified interim analysis, the ivonescimab-based regimen achieved statistically significant and clinically meaningful superiority in overall survival compared to the durvalumab-based regimen, according to the filing.
  • Key secondary endpoints met: The study also met the key secondary endpoints of progression-free survival and objective response rate, the filing stated.
  • Study design: HARMONi-GI1 is a randomized, 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.
  • Comparator arm: The ivonescimab plus chemotherapy regimen was evaluated against durvalumab plus chemotherapy as a first-line treatment for patients with advanced biliary tract cancer.
  • Results presentation pending: Detailed safety and efficacy data are expected to be presented at an upcoming medical congress and published in a peer-reviewed journal, according to the filing.

HARMONi-GI1 Interim Analysis Results and Summit Therapeutics' Role as Partner

Summit Therapeutics Inc. (NASDAQ:SMMT) issued the Form 8-K current report dated August 25, 2026, to disclose that its partner Akeso, Inc. reported positive topline results from the HARMONi-GI1 Phase III clinical study. The study evaluated ivonescimab plus chemotherapy compared with durvalumab plus chemotherapy in patients with advanced biliary tract cancer in the first-line setting. The filing noted that the event triggering the disclosure occurred on August 25, 2026.

According to the filing, at a pre-specified interim analysis, the ivonescimab-based regimen demonstrated statistically significant and clinically meaningful superiority over the durvalumab-based regimen on the primary endpoint of overall survival. The study additionally met key secondary endpoints, specifically progression-free survival and objective response rate. The filing attributed all data generation, management, and analysis exclusively to Akeso, clarifying Summit's role as a partner rather than study sponsor.

The filing noted that detailed results from this first readout of HARMONi-GI1, including both safety and efficacy data, are expected to be presented at an upcoming medical congress and published in a peer-reviewed journal. A press release dated August 25, 2026, was attached as Exhibit 99.1 and incorporated by reference. The Form 8-K was signed by Manmeet S. Soni, Chief Operating Officer, Chief Financial Officer and Director, on behalf of Summit Therapeutics Inc.

What Was Disclosed

Summit Therapeutics filed an 8-K disclosing that partner Akeso reported positive topline Phase III results for ivonescimab plus chemotherapy versus durvalumab plus chemotherapy in advanced biliary tract cancer, meeting overall survival, progression-free survival, and objective response rate endpoints at an interim analysis.