Cogent Biosciences Reports APEX Trial Results for Bezuclastinib in Advanced Systemic Mastocytosis

Cogent Biosciences, Inc. (NASDAQ:COGT) today announced positive top-line results from the registration-directed APEX Part 2 clinical trial of bezuclastinib in patients with advanced systemic mastocytosis (AdvSM) demonstrating clinically meaningful results as measured by consensus criteria used to assess patient response. This is the third positive pivotal trial result for bezuclastinib in 2025, following positive announcements from the SUMMIT trial in NonAdvSM patients and the PEAK trial in GIST patients earlier this year. Based on these top-line data, Cogent expects to submit a new drug application (NDA) to the U.S. Food and Drug Administration (FDA) for bezuclastinib in AdvSM during the first half of 2026. In addition, Cogent plans to present detailed data from the APEX trial at an upcoming scientific meeting in the first half of 2026.

"We are excited to announce the third positive pivotal trial for bezuclastinib this year. The results from the APEX trial demonstrate the clear benefit that a highly selective, highly potent KIT mutant inhibitor is capable of providing to patients with AdvSM," said Andrew Robbins, Cogent's President and Chief Executive Officer. "Coupling rapid, deep, durable responses with the safety and tolerability profile demonstrated by bezuclastinib provides these patients with a new choice to fight their disease without compromising their quality of life. With positive results from APEX, taken together with data from SUMMIT and PEAK, Cogent is preparing for multiple commercial launches in the second half of 2026."

In Part 2 of the APEX trial, 81 AdvSM patients were treated with 150 mg of bezuclastinib, including 57 patients with SM-AHN, 11 patients with ASM and 13 patients with MCL. 68 of these patients were mIWG-MRT-ECNM evaluable for assessment on the primary endpoint. Clinical activity analyzed from these patients showed:

• Primary endpoint: 57% ORR (CR+CRh+PR+CI) per mIWG-MRT-ECNM (mIWG) criteria
  • 49% ORR (CR+CRh+PR) per mIWG
  • At the time of data cut-off, multiple additional patients had achieved unconfirmed response criteria and remain on study awaiting follow-up assessment
    
    
    
     
• Key secondary endpoint: 80% ORR (CR+CRh+PR) per pure pathological response (PPR) criteria
  
  
  
   
• Median time to achieve response was 2.0 months and median duration of response is not yet mature.
  
  
  
   
• Bezuclastinib achieved clear and clinically significant reductions in objective disease markers for these AdvSM patients: