On Sunday, Cogent Biosciences, Inc. (NASDAQ:COGT) revealed updated clinical results from the Open Label Extension (OLE) portion of the SUMMIT trial of bezuclastinib in patients with non-advanced systemic mastocytosis.

Non-advanced systemic mastocytosis is a rare disease that involves mast cell buildup in tissues and organs.

Updated clinical data presented at the American Society of Hematology Annual Meeting & Exposition show:

• 56% mean improvement in Total Symptom Score (TSS) at 24 weeks.
• 76% of patients demonstrated a>50% reduction from baseline in the MS2D2 Total Symptom Score (TSS), with 88% exceeding a 30% reduction from baseline after 24 weeks.
• 49% mean improvement in quality of life Total Score at 24 weeks.
• At 24 weeks of treatment, 31% of patients have already reduced or discontinued best supportive care (BSC) medications.

Pharmacodynamic Data: Bezuclastinib showed rapid, deep, and sustained reductions in serum tryptase over 24 weeks of treatment, including:

• 89% of patients had >50% decrease in serum tryptase levels by four weeks of treatment
• 95% of patients with baseline tryptase ≥20ng/mL achieved <20ng/mL by week 24
• 84% of patients with baseline serum tryptase >11.4ng/ml achieved <11.4ng/mL by week 24

Safety Data

• As of the data cutoff, August 29, 2024, the median duration of bezuclastinib treatment was 56 weeks for patients in the active arm and 40 weeks for placebo patients who crossed over to the OLE.
• The majority of treatment-emergent adverse events were low-grade and reversible, with no treatment-related bleeding or cognitive impairment events reported.

SUMMIT Enrollment Update

• Cogent also announced that enrollment in the registration-directed SUMMIT Part 2 study is complete.
• A total of 179 patients were enrolled and top-line results from the trial are expected in July 2025.

Price Action: COGT stock is up 10.60% at $9.83 at the last check on Monday.

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