Cogent Biosciences Announces Additional Clinical Data from Part 1 of its Ongoing SUMMIT Trial Evaluating Bezuclastinib in Patients with NonAdvanced Systemic Mastocytosis (NonAdvSM)

On June 14, 2024 Cogent Biosciences, Inc. (Nasdaq: COGT), a biotechnology company focused on developing precision therapies for genetically defined diseases, reported additional data from Part 1 of its ongoing SUMMIT clinical trial evaluating the selective KIT D816V inhibitor, bezuclastinib, in patients with nonadvanced systemic mastocytosis (NonAdvSM) (Press release, Cogent Biosciences, JUN 14, 2024, View Source [SID1234644334]). The data are being presented today in a poster presentation at the 2024 European Hematology Association (EHA) (Free EHA Whitepaper) Congress taking place in Madrid, Spain.

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"We are excited to share additional analyses from SUMMIT Part 1 which highlight substantial symptomatic reductions as well as improvement in objective measures of disease," said Andrew Robbins, Chief Executive Officer at Cogent Biosciences. "We remain on track to complete enrollment in the registration-directed SUMMIT Part 2 study in the second quarter of 2025 and report topline results by year-end 2025."

"Nonadvanced systemic mastocytosis is a debilitating hematologic disorder and physicians and patients remain in search of more effective treatment options to fight this disease," said Lindsay Rein, MD, Associate Professor of Medicine in the Division of Hematologic Malignancies and Cellular Therapy at Duke University. "I am impressed with the rapid patient response and reductions seen across all domains at 12 weeks as well as the safety and tolerability. I believe bezuclastinib shows promise in treating nonadvanced systemic mastocytosis where significant unmet needs remain."

SUMMIT Trial Update
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 (MS2D2). As of the cutoff date, December 18, 2023, patients in Part 1 treated at the recommended dose of 100 mg bezuclastinib demonstrated >90% 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 (>50%) 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
Safety Data from SUMMIT Part 1 
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.

EHA Poster Details
Title: Symptom-Focused Results from SUMMIT Part 1: An Ongoing, Randomized, Double-Blind, Placebo-Controlled Phase 2 Clinical Trial of Bezuclastinib in Adult Patients with NonAdvanced Systemic Mastocytosis
Presenting Author: Lindsay Rein, MD
Abstract #: P1055
Poster Session Date and Time: June 14, 2024 at 18:00 – 19:00 CEST

The poster will be available in the Posters and Publications section of Cogent’s website.

Bezuclastinib Clinical Development
Cogent remains on-track to complete enrollment in SUMMIT Part 2 in the second quarter of 2025 and report top-line results by the end of 2025. The Company also remains on track to complete enrollment in the APEX study in patients with advanced systemic mastocytosis (AdvSM) by the end of 2024 and report top-line results mid-2025. Enrollment continues in the Phase 3 registration-enabling PEAK study, which will include approximately 388 second-line, post imatinib patients with Gastrointestinal Stromal Tumors (GIST). Due to rapid enrollment, the Company expects PEAK enrollment to be completed in the third quarter of 2024 with top-line results expected by the end of 2025.