Immuneering Corp-A美股招股说明书(2025-09-25版)

18,959,914 Shares of ClassA Common Stock We are offering 18,959,914 shares of our ClassA common stock, at a price of $9.23 per share. Our ClassA common stock is listed on The Nasdaq Global Market under the symbol “IMRX.” OnSeptember23, 2025, the last reported sale price for our ClassA common stock on The Nasdaq GlobalMarket was $8.59 per share. On September24, 2025, we entered into a securities purchase agreement with Aventis Inc. (referred toherein as the Investor), a wholly owned subsidiary of Sanofi, a French société anonyme, pursuant to whichthe Investor agreed to purchase, subject to certain conditions, up to $25.0million of our ClassA commonstock, or in certain situations in lieu of shares of ClassA common stock, shares of our non-voting ClassBcommon stock, in a private placement. Under the terms of the securities purchase agreement, the privateplacement is subject to and contingent upon the closing of a firm commitment underwritten public offeringby us of our ClassA common stock that results in gross proceeds to us of at least $75.0million and thepricing of which is publicly announced in a press release issued by us on or before September26, 2025(referred to herein as a qualified public offering), and is expected to close concurrent with the completion ofthe qualified public offering. The purchase price per share of ClassA common stock (or per share of ClassBcommon stock in lieu of ClassA common stock) shall be the public offering price per share at which ourClassA common stock is sold to the public in the qualified public offering. The sale of the shares in theconcurrent private placement will not be registered under the Securities Act of 1933, as amended, or the Act.The closing of this offering is not conditioned upon the closing of the concurrent private placement. Underthe terms of the securities purchase agreement, this offering constitutes a qualified public offering.Accordingly, pursuant to the securities purchase agreement, subject to the closing of this offering and theother conditions set forth therein, the Investor has agreed to purchase, and we have agreed to issue and sellto the Investor, an aggregate of 2,708,559shares of Class A common stock at the closing of the concurrentprivate placement. Neither the Securities and Exchange Commission nor any state securities commission has approved ordisapproved of these securities or passed upon the accuracy or adequacy of this prospectus supplement or theaccompanying prospectus. Any representation to the contrary is a criminal offense. Investing in our securities involves risks. See “Risk Factors” beginning on pageS-9of this prospectussupplement and in the documents incorporated by reference in this prospectus supplement concerning factorsyou should consider before investing in our securities. Per ShareTotalPublic offering price$9.23$175,000,006Underwriting discounts and commissions$0.5538$10,500,000Proceeds to us, before expenses$8.6762$164,500,006(1) (1)We have agreed to reimburse the underwriters for certain of their expenses. See “Underwriting” beginning on pageS-22of this prospectus supplement for more information about these arrangements. We have granted the underwriters the option to purchase up to 2,843,987 additional shares of ourClassA common stock from us at the public offering price, less underwriting discounts and commissions.The underwriters may exercise this right at any time, in whole or in part, within 30days following the dateof this prospectus supplement. The underwriters expect to deliver the shares of ClassA common stock to investors on or aboutSeptember26, 2025. The shares of ClassA common stock will be delivered in book-entry form through thefacilities of The Depository Trust Company on or about September26, 2025. Joint Bookrunners Oppenheimer & Co. Leerink Partners The date of this prospectus supplement is September24, 2025. TABLE OF CONTENTS Prospectus Supplement PageABOUT THIS PROSPECTUS SUPPLEMENTS-1CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSS-3PROSPECTUS SUPPLEMENT SUMMARYS-5THE OFFERINGS-7RISK FACTORSS-9USE OF PROCEEDSS-11DIVIDEND POLICYS-12DILUTIONS-13CONCURRENT PRIVATE PLACEMENTS-14CERTAIN U.S. FEDERAL INCOME TAX CONSEQUENCESS-17UNDERWRITINGS-22LEGAL MATTERSS-32EXPERTSS-32WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCES-33 ABOUT THIS PROSPECTUS1SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS2WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE3THE COMPANY5RISK FACTORS6USE OF PROCEEDS7DESCRIPTION OF CAPITAL STOCK8DESCRIPTION OF DEBT SECURITIES12DESCRIPTION OF WARRANTS19DESCRIPTION OF UNITS20GLOBAL SECURITIES21PLAN OF DISTRIBUTION25LEGAL MATTERS27EXPERTS27 ABOUT THIS PROSPECTUS SUPPLEMENT This document is in two parts. The first part is this prospectus supplement, which describes the terms ofthe offering of the securities offered hereby and also adds to and updates the information contained in theaccompanying prospectus and the documents incorporated by referenc