UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.    )

Filed by the Registrant  ☒

Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐ Preliminary Proxy Statement

☐ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☐ Definitive Proxy Statement

☒ Definitive Additional Materials

☐ Soliciting Material under §240.14a-12

FOGHORN THERAPEUTICS INC.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

☒ No fee required.

☐ Fee paid previously with preliminary materials.

☐ Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11.

Your Vote Counts! FOGHORN THERAPEUTICS INC. 2022 Annual Meeting Vote by June 20, 2022 11:59 PM ET GENERAL BROKER Hextone, Inc. P.O. Box 91421 Farmingdale, NY 11735 148,294 322,224 OF 2 Ricky Campana P.O. Box 123456 Suite 500 30# 51 Mercedes Way Edgewood, NY 11717 FLASHID-JOB# You invested in FOGHORN THERAPEUTICS INC. and it’s time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy material for the shareholder meeting to be held on June 21, 2022. Get informed before you vote View the Notice & Proxy Statement, Form 10-K online OR you can receive a free paper or email copy of the material(s) by requesting prior to June 07, 2022. If you would like to request a copy of the material(s) for this and/or future shareholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. For complete information and to vote, visit www.ProxyVote.com Control # XXXX XXXX XXXX XXXX Smartphone users Vote in Person at the Meeting* Point your camera here and June 21, 2022 vote without entering a 9:00 AM EDT control number Annual meeting to be held live via the Internet Please visit www.proxydocs.com/FHTX for more details *If you choose to vote these shares in person at the meeting, you must request a “legal proxy.” To do so, please follow the instructions at www.ProxyVote.com or request a paper copy of the materials, which will contain the appropriate instructions. Please check the meeting materials for any special requirements for meeting attendance.

Vote at www.ProxyVote.com Control # XXXX XXXX XXXX XXXX THIS IS NOT A VOTABLE BALLOT FOGHORN THERAPEUTICS INC. This is an overview of the proposals being presented at the 2022 Annual Meeting Vote by June 20, 2022 upcoming shareholder meeting. Please follow the instructions on 11:59 PM ET the reverse side to vote these important matters. Voting Items Board Recommends 1. Election of Directors Nominees: 01 Adrian Gottschalk For 02 Adam Koppel, M.D.,Ph.D. For 03 Ian F. Smith For 2. Ratify Selection of Deloitte & Touche LLP as Our Independent Registered Public Accounting Firm for the Fiscal Year For Ending December 31, 2022 NOTE: Such other business as may properly come before the meeting or any adjournment thereof. Under New York Stock Exchange rules, brokers may vote “routine” matters at their discretion if your voting instructions are not communicated to us at least 10 days before the meeting. We will nevertheless follow your instructions, even if the broker’s discretionary vote has already been given, provided your instructions are received prior to the meeting date. 1.00000 322,224 FLASHID-JOB# 148,294