Foghorn Therapeutics Inc.

To the Stockholders and the Board of Directors of Foghorn Therapeutics Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Foghorn Therapeutics, Inc. and its subsidiary (the "Company") as of December 31, 2025 and 2024, the related consolidated statements of operations and comprehensive loss, shareholders' deficit, and cash flows, for the years then ended, and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for the years then ended, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Collaboration Revenue - Refer to Notes 2 and 8 to the financial statements

Critical Audit Matter Description

During the year ended December 31, 2025, the Company recognized revenue of $30.9 million. As discussed in Note 2 to the consolidated financial statements, at inception, the Company determines whether contracts are within the scope of ASC 606, Revenue from Contracts with Customers, or ASC 606, or other topics. Under ASC 606, the Company recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration that the Company expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies a performance obligation. For performance obligations where revenue is recognized over time, the Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The Company recognizes revenue using the cost-to-cost method, where the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. The impacts on revenue from changes in total estimated costs are recognized on a cumulative basis in the period when the changes occur. If estimates of the total cost change, or if contract amendments change the scope of the performance obligation, the required adjustments to revenue could be material.

We identified revenue recognition as a critical audit matter because of the judgments necessary for management to estimate total costs to satisfy the applicable performance obligation under the contract. This required a high degree of auditor judgment when performing audit procedures to audit management’s estimates of total costs and evaluating the results of those procedures.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to collaboration revenue included the following, among others:

•We obtained and read the relevant contracts and other documents related to the collaboration agreement.

•We evaluated the Company’s accounting analysis for the applicable contract, including the application to the relevant authoritative guidance.

•We tested the amount of revenue recognized, including the measurement of progress for revenue that is recognized over time.

•We tested management’s estimate of the total cost of fulfilling the performance obligation, including retrospective reviews of the changes in such estimates over time.

•We also discussed the basis for key assumptions with the Company's research and development personnel, who oversee the completion of the collaboration arrangement.

/s/Deloitte & Touche LLP

Boston, Massachusetts

March 11, 2026

We have served as the Company’s auditor since 2018.