(Mark One) For the quarterly period ended March31, 2026 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934For the transition period from __________________ to __________________Commission File Number: 001-39634______________________ Foghorn Therapeutics Inc.(Exact Name of Registrant as Specified in its Charter) ______________________ Registrant’s telephone number, including area code: 617-586-3100______________________ Indicate by check mark whether the registrant (1)has filed all reports required to be filed by Section13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12months (or for such shorter period that the registrant was required to file such reports), and (2)has been subject to such filing requirements for the past 90 days.YesNo Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).YesNo Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company.See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act. If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financialaccounting standards provided pursuant to Section13(a) of the Exchange Act. Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).YesNo Table of Contents PART I.FINANCIAL INFORMATION2Item 1.Financial Statements (Unaudited)2Condensed Consolidated Balance Sheets2Condensed Consolidated Statements of Operations and Comprehensive Loss3Condensed Consolidated Statements of Stockholders’ Deficit4Condensed Consolidated Statements of Cash Flows5Notes to Unaudited Condensed Consolidated Financial Statements6Item 2.Management’s Discussion and Analysis of Financial Condition and Results of Operations17Item 3.Quantitative and Qualitative Disclosures About Market Risk24Item 4.Controls and Procedures24PART II.OTHER INFORMATION26Item 1.Legal Proceedings26Item 1A.Risk Factors26Item 5.Other Information26Item 6.Exhibits27Signatures28 SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS This Quarterly Report on Form 10-Q contains forward-looking statements that are based on management’s beliefs and assumptionsand on information currently available to management. All statements other than statements of historical facts contained in thisQuarterly Report on Form 10-Q are forward-looking statements. In some cases, you can identify forward-looking statements by termssuch as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,”“estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. Forward-looking statements include, but are not limited to, statements concerning: •the initiation, timing, progress, enrollment, results, and timing of results and regulatory filings of our research anddevelopment programs and our preclinical and clinical studies, including those included in our collaboration with EliLilly and Company (“Lilly”);•our ability to advance any product candidates that we may develop and to successfully complete preclinical and clinicalstudies;•our ability to leverage our initial programs to develop additional product candidates using our Gene Traffic Controlplatform;•developments related to our competitors and our industry;•our ability to expand the target populations of our programs and the availability of patients for clinical testing;•our ability to obtain regulatory approval for FHD-909 and any future product candidates from the U.S. Food and DrugAdministration (the “FDA”) and other regulatory authorities;•our ability to identify and enter into future license agreements and collaborations;•our ability to continue to rely on our contract development and manufacturing organizations (“CDMOs”) or contractresearch organizations (“CROs”), including those located outside the United States, such as those located in China, forour manufacturing and research needs;•statutory and regulatory developments in the United States and foreign countries, especially in China, including China’sAnti-Foreign Sanctions Law and its implementing regulations;•general economic conditions, including recessionary conditions, interest rates, monetary fluctuations and supply chainconstraints;•ongoing and potential geopolitical instability and armed conflicts;•our ability to attract and