Cogent Biosciences announces clinical data from Part 1 of ongoing SUMMIT trial

Cogent Biosciences announced additional data from Part 1 of its ongoing SUMMIT clinical trial evaluating the selective KIT D816V inhibitor, bezuclastinib, in patients with nonadvanced systemic mastocytosis. The data are being presented today in a poster presentation at the 2024 European Hematology Association Congress taking place in Madrid, Spain. SUMMIT is a randomized, double-blind, placebo-controlled, global, multicenter, Phase 2 clinical trial of bezuclastinib in patients with NonAdvSM. Part 1 of the trial was designed to determine the recommended dose of bezuclastinib. In addition, the study was designed to explore the effects of bezuclastinib on the signs and symptoms of NonAdvSM, including assessment of disease-specific symptom severity using a novel patient-reported outcome measure, the Mastocytosis Symptom Severity Daily Diary. As of the cutoff date, December 18, 2023, patients in Part 1 treated at the recommended dose of 100 mg bezuclastinib demonstrated greater than90% reductions across all markers of mast cell burden. Additional data also show meaningful reduction in symptom severity and objective measures of disease, including: Substantial reduction in mast cell reactions and patients’ most severe symptoms as measured by MS2D2 Clinically meaningful reduction in all individual MS2D2 TSS symptoms and across domains, as well as additional symptoms including dizziness, diarrhea severity, and brain fog Clinically meaningful improvement in skin symptoms as well as objective reduction in skin lesions. Consistent with results previously reported, as of the December 18, 2023 cutoff date, the recommended dose of 100 mg demonstrates a favorable safety and tolerability profile. There were no bleeding or cognitive impairment adverse events reported and no serious adverse events reported.