Cogent Biosciences presents pivotal APEX trial data for bezuclastinib in advanced systemic mastocytosis
Cogent Biosciences (NASDAQ:COGT) announced detailed clinical results from its registration-directed APEX trial evaluating its investigational precision therapy, bezuclastinib, in patients with advanced systemic mastocytosis (AdvSM).
The data, shared at the 2026 European Hematology Association (EHA) Congress in Stockholm, Sweden, demonstrate rapid, deep, and durable clinical improvements across evaluated disease-modifying metrics.
Advanced systemic mastocytosis is a rare, progressive myeloid disorder driven heavily by the somatic KIT D816V mutation, which leads to an uncontrolled accumulation of neoplastic mast cells in internal organs and bone marrow.
Bezuclastinib is designed as an oral, highly selective tyrosine kinase inhibitor engineered to potently inhibit this specific mutational driver.
Primary results from the pivotal cohort revealed robust response rates across established clinical assessment criteria.
Bezuclastinib achieved an updated objective response rate (ORR) of 65% when measured by the modified International Working Group-Myeloproliferative Neoplasms Research and Treatment (mIWG) parameters.
When evaluated by Pure Pathological Response (PPR) criteria, the candidate posted an 81% ORR.
The data further outlined a pronounced impact on underlying mast cell burden.
Investigators noted that 91% of patients achieved a greater than or equal to 50% reduction in variant allele frequency, while 89% achieved a greater than or equal to 50% reduction in bone marrow mast cells or demonstrated a complete clearance of cell aggregates.
Progression-free survival and overall survival metrics showed ongoing durability, paired with a safety and tolerability profile that remained consistent with prior mid-stage updates.
Based on the strength of the clinical dataset, Cogent confirmed it remains on track to submit its New Drug Application (NDA) for bezuclastinib in advanced systemic mastocytosis to the FDA before the end of June 2026.
