Cogent Biosciences (COGT) reported updated results Monday from the open-label extension portion of the SUMMIT clinical trial evaluating bezuclastinib in patients with nonadvanced systemic mastocytosis.

The biotech firm said the clinical results focus on 27 patients in the open-label extension who were treated with the once-daily 100 mg dose of bezuclastinib.

Cogent said that at 24 weeks of treatment, 31% of patients had reduced or discontinued best supportive care medications. It also said Bezuclastinib "showed rapid, deep, and sustained reductions" in serum tryptase during 24 weeks of treatment.

Shares of Cogent Biosciences were down 19% in recent premarket activity.