艾吉纳斯美股招股说明书(2026-08-17版)

Agenus Inc. 77,976,718 Shares Common Stock Offered by the Selling Securityholders The selling securityholders may, from time to time and at their respective option, offer and sell up to 77,976,718 shares in the aggregate ofcommon stock identified above, of which 1,626,015 shares are presently issued and outstanding, 21,409,212 shares are issuable upon exercise ofpresently issued and outstanding pre-funded warrants to purchase common stock and 54,941,491 shares are issuable upon exercise of presently issuedand outstanding purchase warrants to purchase common stock, from time to time in one or more offerings. This prospectus provides you with a generaldescription of these securities. See the section of this prospectus entitled “Description of Securities” for more information. We will receive the proceedsfrom any exercise of the warrants for cash, if any. We will not receive any proceeds from the sale of our common stock by the selling securityholders.The selling securityholders are under no obligation to us to sell any of the shares covered by this prospectus and may sell all, some, or none of suchshares. Each time any of the selling securityholders offers and sells securities, such selling securityholders may provide a supplement to this prospectusthat contains specific information about the offering and the amounts, prices and terms of the securities. The supplement may also add, update or changeinformation contained in this prospectus with respect to that offering. You should carefully read this prospectus and the applicable prospectussupplement before you invest in any of our securities. The selling securityholders, together or separately, may offer and sell the securities described in this prospectus and any prospectus supplement toor through one or more underwriters, dealers and agents, or directly to purchasers, or through a combination of these methods. If any underwriters,dealers or agents are involved in the sale of any of the securities, their names and any applicable purchase price, fee, commission or discountarrangement between or among them will be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement. Seethe sections of this prospectus entitled “About this Prospectus” and “Plan of Distribution” for more information. No securities may be sold withoutdelivery of this prospectus and the applicable prospectus supplement describing the method and terms of the offering of such securities. INVESTING IN OUR SECURITIES INVOLVES RISKS.SEE THE “RISK FACTORS” ON PAGE 7 OF THISPROSPECTUS AND ANY SIMILAR SECTION CONTAINED IN THE APPLICABLE PROSPECTUSSUPPLEMENT CONCERNING FACTORS YOU SHOULD CONSIDER BEFORE INVESTING IN OURSECURITIES. Our common stock is listed on the Nasdaq Capital Market under the symbol “AGEN.” On August13, 2026, the last reported sale price of ourcommon stock on the Nasdaq Capital Market was $7.00 per share. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities orpassed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense. Table of Contents TABLE OF CONTENTS ABOUT THIS PROSPECTUSWHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCETHE COMPANYRISK FACTORSUSE OF PROCEEDSDESCRIPTION OF SECURITIESPRIVATE PLACEMENT OF SECURITIESSELLING SECURITYHOLDERSPLAN OF DISTRIBUTIONLEGAL MATTERSEXPERTS Table of Contents ABOUT THIS PROSPECTUS This prospectus is part of a registration statement that we filed with the U.S.Securities and Exchange Commission (the “SEC”) using a “shelf”registration process. By using a shelf registration statement, the selling securityholders may, from time to time and if they respectively choose to do so,sell up to 77,976,718 shares of common stock in one or more offerings as described in this prospectus. The registration statement of which thisprospectus is a part is being filed with the SEC in satisfaction of our obligations under the Registration Rights Agreement, dated as of July13, 2026, byand among us and the selling securityholders party thereto. This prospectus relates to the possible resale of such shares by the selling securityholdersfrom time to time, but the selling securityholders are under no obligation to us to sell such shares. In connection with the offer and sale of securities by the selling securityholders, the selling securityholders may provide a prospectus supplementto this prospectus that contains specific information about the securities being offered and sold and the specific terms of that offering. We may alsoauthorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. Any suchprospectus supplement or free writing prospectus may also add, update or change information contained in this prospectus with respect to that offering.If there is any inconsistency between the informat