Cogent Biosciences Announces Positive Top-line Results of APEX Trial of Bezuclastinib in Patients with Advanced Systemic Mastocytosis (AdvSM)

Core Insights - Cogent Biosciences announced positive top-line results from the APEX Part 2 clinical trial of bezuclastinib for advanced systemic mastocytosis (AdvSM), marking the third positive pivotal trial result for the drug in 2025 [1][2] - The company plans to submit a new drug application (NDA) to the FDA for bezuclastinib in AdvSM in the first half of 2026 and will present detailed data from the APEX trial at a scientific meeting during the same period [1][7] Clinical Trial Results - In the APEX Part 2 trial, 81 AdvSM patients were treated with 150 mg of bezuclastinib, with 68 patients evaluable for the primary endpoint [2][5] - The trial showed a 57% objective response rate (ORR) per mIWG criteria and an 80% ORR per pure pathological response (PPR) criteria [4][5] - Significant clinical activity was observed, with 89% of patients achieving a ≥50% reduction in serum tryptase and bone marrow mast cells, and 91% showing a ≥50% reduction in KIT D816V variant allele frequency [3][4] Safety and Tolerability - Bezuclastinib demonstrated a favorable safety profile, with only 14.8% of patients requiring dose reduction and no discontinuations due to treatment-related adverse events [6][4] - The most common treatment-related adverse events included hair color change (30.9%), neutropenia (29.6%), and altered taste (28.4%) [6] Future Plans - Cogent is preparing for multiple commercial launches in the second half of 2026 based on the positive results from the APEX trial and previous trials [2][11] - The company will host a live webcast to discuss the full data from the SUMMIT trial and the APEX results [8]