Summit Therapeutics Inc. filed a Form 8-K on August 5, 2026, announcing the planned initiation of the global Phase II/III HARMONi-GU1 trial, which will study ivonescimab in urothelial carcinoma.

Key Highlights

  • New trial announced: Summit Therapeutics is expanding its global registration-enabling clinical development program for ivonescimab into urothelial carcinoma, also described as bladder cancer.
  • Trial design: HARMONi-GU1 is a global, multi-regional Phase II/III study evaluating ivonescimab plus enfortumab vedotin compared to pembrolizumab plus enfortumab vedotin as first-line therapy.
  • Patient population: The trial targets patients with previously untreated locally advanced or metastatic urothelial carcinoma.
  • Site activations: Global clinical trial site activations for HARMONi-GU1 are planned to begin later in 2026, according to the filing.
  • Exchange listing: Summit Therapeutics common stock trades on The Nasdaq Stock Market LLC under the symbol SMMT.

Summit Therapeutics Plans HARMONi-GU1 Trial for Urothelial Carcinoma

According to the filing, Summit Therapeutics Inc. issued a press release on August 5, 2026, disclosing the expansion of its global registration-enabling clinical development program for ivonescimab into urothelial carcinoma, commonly referred to as bladder cancer. The company disclosed plans to initiate the HARMONi-GU1 trial, described as a global, multi-regional Phase II/III study.

The filing states that HARMONi-GU1 will evaluate ivonescimab in combination with the antibody-drug conjugate enfortumab vedotin, referred to as EV, compared against pembrolizumab plus EV. This comparison is intended as a first-line therapy assessment in patients with previously untreated locally advanced or metastatic urothelial carcinoma. The filing does not specify a total enrollment target or primary endpoint in the 8-K text itself.

The company reported that global clinical trial site activations for HARMONi-GU1 will begin later this year. The 8-K was signed by Manmeet S. Soni in his capacity as Chief Operating Officer, Chief Financial Officer, and Director, identified as the Principal Financial Officer. A press release dated August 5, 2026, was attached as Exhibit 99.1 and incorporated by reference into the filing.

What Was Disclosed

Summit Therapeutics disclosed plans to launch the HARMONi-GU1 Phase II/III trial studying ivonescimab plus enfortumab vedotin versus pembrolizumab plus enfortumab vedotin in first-line urothelial carcinoma, with site activations expected later in 2026.