Cogent Biosciences Inc. (NASDAQ: COGT) reported updated results from its APEX pivotal trial of bezuclastinib in patients with advanced systemic mastocytosis. The trial showed a 65% objective response rate using modified International Working Group criteria and an 81% response rate using pure pathological response criteria.

As of March 31, 2026, 81 patients with advanced systemic mastocytosis received 150 mg of bezuclastinib in the trial's second part. The group included 57 patients with systemic mastocytosis with associated hematologic neoplasm, 11 patients with aggressive systemic mastocytosis and 13 patients with mast cell leukemia.

The treatment demonstrated reductions in disease markers, with 89% of patients achieving at least 50% reduction in serum tryptase and bone marrow mast cells. Additionally, 91% of patients showed at least 50% reduction in variant allele frequency.

The 12-month progression-free survival rate was 79% and the 12-month overall survival rate was 87%. Median duration for both measures had not been reached at the data cutoff.

Common treatment-related adverse events included hair color change (31%), neutropenia (31%), altered taste (28%), thrombocytopenia (25%), and liver enzyme elevations (21%). Most liver enzyme elevations were low grade and reversible.

The company plans to submit a New Drug Application in June 2026 and expects to launch bezuclastinib commercially later this year following FDA approval. The data was presented at the 2026 European Hematology Association Congress in Stockholm.

The information is based on a company press release.