Cogent Biosciences EHA Data: Bezuclastinib Safety Edge Over Ayvakit

Cogent Biosciences (COGT) presented updated clinical data for bezuclastinib at the European Hematology Association (EHA) 2026 Congress on Friday. The slide deck covered results across systemic mastocytosis and gastrointestinal stromal tumors.

The presentation focused on two forms of systemic mastocytosis: non-advanced (NonAdvSM) and advanced (AdvSM). Cogent is developing bezuclastinib as a KIT D816V inhibitor, competing with Blueprint Medicines' Ayvakit (avapritinib) in a market that has shifted toward targeted therapy.

Data from the Phase 2 SUMMIT trial in NonAdvSM showed sustained symptom control across multiple patient-reported measures. Cogent highlighted a safety profile it argues differentiates bezuclastinib from avapritinib. Cognitive adverse events and edema have been limiting factors for the Blueprint drug in some patients.

In AdvSM, the Phase 2 APEX trial showed durable responses in a heavily pretreated population. Median duration of response had not been reached at the data cutoff, the company said. That metric could support a registration filing if it holds.

The EHA presentation comes as Cogent prepares for a potential regulatory submission in NonAdvSM later this year. The company expects to file a new drug application with the FDA in the second half of 2026, assuming the SUMMIT data holds up at a planned interim analysis.

Cogent's stock has been volatile this year, swinging between optimism over bezuclastinib's commercial potential and skepticism about whether it can unseat Ayvakit. Ayvakit generated over $400 million in 2025 sales for Blueprint. The EHA data gives analysts and investors a fresh set of numbers to model against.

A key question the presentation did not fully answer is whether bezuclastinib's efficacy is truly comparable to avapritinib in the hardest-to-treat AdvSM patients. The APEX trial is single-arm, making cross-trial comparisons difficult. Cogent's argument rests on the safety advantage. Regulators will want to see a cleaner efficacy signal before approving a switch.

The company also provided an update on bezuclastinib in gastrointestinal stromal tumors (GIST), where it is testing the drug against a different KIT mutation profile. That program remains secondary to the mastocytosis franchise for now.

Cogent ended the session with its slide deck publicly available on its investor relations page. The next major catalyst is the SUMMIT interim analysis, expected in the third quarter.