Cogent Biosciences Provides Corporate Updates , Fourth Quarter and Full Year 2021 Financial Results APEX, SUMMIT and PEAK bezuclastinib clinical trials actively enrolling patients APEX initial clinical data presentation

Cogent Biosciences Provides Corporate Updates, Fourth Quarter

and Full Year 2021 Financial Results

APEX, SUMMIT and PEAK bezuclastinib clinical trials actively enrolling patients

APEX initial clinical data presentation expected in the first half of 2022

R&D Investor Event planned for April 8, 2022

Ended 2021 with $219.7 million in cash, sufficient to fund operations into 2024

CAMBRIDGE, Mass. and BOULDER, Colo., March 15, 2022 - Cogent Biosciences, Inc. (Nasdaq: COGT), a biotechnology company focused on developing precision therapies for genetically defined diseases, today announced financial results for the fourth quarter and year ended December 31, 2021.

"In 2021, Cogent achieved substantial progress toward our goal of establishing bezuclastinib as a best-in-class KIT mutant inhibitor for systemic mastocytosis and gastrointestinal stromal tumor (GIST) patients," said Andrew Robbins, President and CEO of Cogent Biosciences. "All three late-stage bezuclastinib clinical trials are actively enrolling patients, and we look forward to presenting initial clinical data from APEX in the first half of 2022. In addition, we are excited about the progress the Cogent Research Team has made to date and look forward to sharing further details on bezuclastinib, as well as our growing portfolio, at our upcoming R&D Investor Event."

Key Clinical, Research and Corporate Highlights

Fourth Quarter and Year End 2021 Summarized Financial Results

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. Cogent Biosciences is based in Cambridge, MA and Boulder, CO. Visit our website for more information at www.cogentbio.com. Follow Cogent Biosciences on social media: Twitter and LinkedIn. Information that may be important to investors will be routinely posted on our website and Twitter.

Forward Looking Statements

This 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 anticipated cash runway, the expectation to present preliminary clinical data from APEX in the first half of 2022, the company's planned R&D investor event in April 2022, the anticipated move for the Cogent Research Team into its newly-built, state-of-the-art research facility in Boulder this spring, and the expectation that the company's AACR poster presentations will be made available through the AACR conference website on schedule. 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 Annual Report on Form 10-K filed with the SEC, as well

as discussions of potential risks, uncertainties, and other important factors in our subsequent filings 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.

COGENT BIOSCIENCES, INC.

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