COGT Cogent Biosciences Inc

Cogent Biosciences, Inc. (Nasdaq: COGT), a biotechnology company focused on developing precision therapies for genetically defined diseases, today announced updated clinical results from the Open Label Extension (OLE) portion of SUMMIT, a clinical trial evaluating bezuclastinib in patients with nonadvanced systemic mastocytosis (NonAdvSM). The OLE data are being presented at the 66th American Society of Hematology (ASH 2024) Annual Meeting & Exposition taking place December 7-10, 2024 in San Diego, CA.

“The rapid, deep, and sustained symptomatic improvement reported by SUMMIT patients receiving bezuclastinib is very impressive,” said Daniel J. DeAngelo, M.D., Ph.D., Chief of the Division of Leukemia at the Dana-Farber Cancer Institute and Professor of Medicine, Harvard Medical School. “Coupled with its favorable tolerability profile, bezuclastinib has clear potential to establish itself as the best-in-class KIT inhibitor for systemic mastocytosis patients.”

“The SUMMIT data reported today are encouraging to thousands of NonAdvSM patients around the world who are waiting for a novel treatment that can rapidly and meaningfully improve a wide variety of symptoms that impact their daily lives,” said Andrew Robbins, Cogent’s President and Chief Executive Officer. “We set out earlier this year to enroll our registration-directed SUMMIT Part 2 trial, and I’m excited to announce that based on the overwhelming demand from investigators and patients around the world, we’ve completed enrollment in the study with 179 patients more than six months ahead of schedule. Top-line results are now expected in July 2025, meaning we have dramatically accelerated our timeline as we aim to make bezuclastinib available to all NonAdvSM patients.”

Patient DemographicsSUMMIT is a registration-directed, randomized, double-blind, placebo-controlled, global, multicenter, clinical trial of bezuclastinib in patients with NonAdvSM. In SUMMIT Part 1, patients received bezuclastinib or placebo for a 12-week period to determine the recommended dose for use in the pivotal portion of the trial, SUMMIT Part 2. Earlier this year, Cogent announced that the recommended go-forward dose was selected at once-daily 100 mg. After the initial 12-week period, all patients were given the opportunity to receive bezuclastinib in the SUMMIT Open Label Extension (OLE). The clinical results presented today focus on 27 patients in the OLE who were treated with the once-daily 100 mg dose of bezuclastinib. The median age of patients at study entry was 52 years (ranging from 36-76 years). One patient had received prior avapritinib.

Patient Reported Outcomes (PRO) DataSUMMIT patients were evaluated for signs of clinical activity over 24 weeks using multiple PRO measures, including the Mastocytosis Symptom Severity Daily Diary (MS2D2) and the Mastocytosis Quality-of-Life (MC-QoL) scale. Updated clinical data presented today show:

• 56% mean improvement in Total Symptom Score (TSS) at 24 weeks
• 76% of patients demonstrated >50% reduction from baseline in MS2D2 Total Symptom Score (TSS) with 88% of patients exceeding 30% reduction from baseline after 24 weeks
• 49% mean improvement in MC-QoL Total Score at 24 weeks

At 24 weeks of treatment, 31% of patients have already reduced or discontinued best supportive care (BSC) medications.

Pharmacodynamic DataBezuclastinib showed rapid, deep, and sustained reductions in serum tryptase over the course of 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 DataAs 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. The most common treatment related adverse events were hair discoloration and transaminase elevations. All patients experiencing elevated transaminases were asymptomatic and reversible: five patients resolved without any dose modifications and remain on study; two patients resolved with dose reduction and remain on study, one of whom re-escalated to original dose; and two patients resolved following discontinuation, one of whom was presented previously at ASH 2023. There were no other discontinuations due to adverse events.

SUMMIT Enrollment UpdateCogent also announced today that enrollment in the registration-directed SUMMIT Part 2 study is now complete. In the nine months between February and October 2024, 265 NonAdvSM patients were screened for SUMMIT Part 2 at 70 clinical sites, concentrated predominantly in the U.S. and Western Europe. More than 90% of these patients were naïve to KIT inhibitor therapy. A total of 179 patients were enrolled and top-line results from the trial are expected in July 2025.

Webcast Information and ASH PosterCogent will host a webcast today, Monday, December 9, 2024, at 8:00 a.m. ET to discuss these updated SUMMIT clinical results. The live event will be available on the Investors & Media page of Cogent’s website at investors.cogentbio.com. A replay of the webcast will be available approximately two hours after the completion of the event and will be archived for up to 30 days. The ASH poster is available to registered conference attendees and is also in the Posters and Publications section of Cogent’s website at www.cogentbio.com/research. 

About Cogent Biosciences, Inc. Cogent Biosciences is a biotechnology company focused on developing precision therapies for genetically defined diseases. The most advanced clinical program, bezuclastinib, is a selective tyrosine kinase inhibitor that is designed to potently inhibit the KIT D816V mutation as well as other mutations in KIT exon 17. KIT D816V is responsible for driving systemic mastocytosis, a serious disease caused by unchecked proliferation of mast cells. Exon 17 mutations are also found in patients with advanced gastrointestinal stromal tumors (GIST), a type of cancer with strong dependence on oncogenic KIT signaling. In addition to bezuclastinib, the Cogent Research Team is developing a portfolio of novel targeted therapies to help patients fighting serious, genetically driven diseases initially targeting mutations in FGFR2, ErbB2, PI3Kα and KRAS. Cogent Biosciences is based in Waltham, MA and Boulder, CO. Visit our website for more information at www.cogentbio.com. Follow Cogent Biosciences on social media: X (formerly known as Twitter) and LinkedIn. Information that may be important to investors will be routinely posted on our website and X.

Forward Looking StatementsThis press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including, but not limited to, statements regarding: the company’s expectation to present top-line results from SUMMIT Part 2 in July 2025; the potential for bezuclastinib to establish itself as the best-in-class KIT inhibitor for systemic mastocytosis patients; and the company’s goal of making bezuclastinib available to all NonAdvSM patients. The use of words such as, but not limited to, "anticipate," "believe," "continue," "could," "estimate," "expect," "intend," "may," "might," "plan," "potential," "predict," "project," "should," "target," "will," or "would" and similar words expressions are intended to identify forward-looking statements. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, our clinical results, the rate of enrollment in our clinical trials and other future conditions. New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements. We may not actually achieve the forecasts or milestones disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Such forward-looking statements are subject to a number of material risks and uncertainties including but not limited to those set forth under the caption "Risk Factors" in Cogent's most recent Quarterly Report on Form 10-Q filed with the SEC. Any forward-looking statement speaks only as of the date on which it was made. Neither we, nor our affiliates, advisors or representatives, undertake any obligation to publicly update or revise any forward-looking statement, whether as result of new information, future events or otherwise, except as required by law. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to the date hereof.

Contact:Christi WaarichSenior Director, Investor Relationschristi.waarich@cogentbio.com617-830-1653