免疫生物公司美股招股说明书(2025-12-29版)

Up to $459,972,480 of Common Stock We have entered into an Open Market Sale AgreementSM, as amended by Amendment No.1 to Open Market Sale AgreementSM(the “saleagreement”) with Jefferies LLC (“Jefferies”) relating to shares of our common stock, $0.0001par value per share, offered by this prospectussupplement. In accordance with the terms of the sale agreement, we may offer and sell shares of our common stock from time to time through Jefferies,acting as our sales agent, pursuant to this prospectus supplement. In accordance with the terms of the sale agreement, and subject to the terms thereof, Our common stock is listed on The Nasdaq Global Select Market (“Nasdaq”) under the symbol “IBRX.” The closing price of our common stockon December22,2025, as reported by Nasdaq, was $2.27per share. Sales, if any, of shares of our common stock under the sale agreement may be made by any method permitted by law. Jefferies is not required tosell any specific amount of securities but will act as our sales agent using commercially reasonable efforts to sell on our behalf all of the shares ofcommon stock requested to be sold by us, consistent with its normal trading and sales practices, applicable state and federal laws, rules and regulations Jefferies will be entitled to compensation at a commission rate of up to 3.0% of the gross proceeds of any shares of common stock sold under thesale agreement. In connection with the sale of the common stock on our behalf, Jefferies may be deemed to be an “underwriter” within the meaning ofthe Securities Act of 1933, as amended (the “Securities Act”) and the compensation of Jefferies may be deemed to be underwriting commissions or Investing in our common stock involves significant risks. See “Risk Factors” beginning on pageS-6 of thisprospectus supplement, as well as the information under the caption “Risk Factors” in our Annual Report onForm10-K for the year ended December31,2024, the information under the caption “Risk Factors” in our QuarterlyReport on Form10-Q for the three months ended September30,2025, and under similar headings in the other Neither the U.S. Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved ofthese securities or determined if this prospectus supplement or the accompanying base prospectus is truthful or complete. Any representation to Jefferies The date of this prospectus supplement is December 23, 2025. Table of Contents TABLE OF CONTENTS About This Prospectus Supplement and the Accompanying Base ProspectusProspectus Supplement SummaryThe Offering FOR INVESTORS OUTSIDE THE UNITED STATES: WE HAVE NOT, AND THE SALES AGENT HAS NOT, DONE ANYTHING THATWOULD PERMIT THIS OFFERING OR POSSESSION OR DISTRIBUTION OF THIS PROSPECTUS SUPPLEMENT AND ANY FREEWRITING PROSPECTUS THAT WE HAVE AUTHORIZED FOR USE IN CONNECTION WITH THIS OFFERING IN ANYJURISDICTION WHERE ACTION FOR THAT PURPOSE IS REQUIRED, OTHER THAN IN THE UNITED STATES. PERSONS Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT AND THE ACCOMPANYING BASE PROSPECTUS We are providing information to you about this offering of our common stock in two separate documents that are bound together: (1)thisprospectus supplement, which describes the specific terms of this offering and (2)the accompanying base prospectus, which provides generalinformation, some of which may not apply to this offering. This prospectus supplement may also add to, update or change information contained in theaccompanying base prospectus. If information in this prospectus supplement is inconsistent with the accompanying base prospectus, you should rely on This prospectus supplement is part of an automatic shelf registration statement on FormS-3 ASR (FileNo.333-278770) that we have filed withthe SEC as a “well-known seasoned issuer” as defined in Rule405 under the Securities Act. Under the shelf registration process, we may, from time totime, offer and sell any combination of our securities described in the base prospectus filed with such registration statement in one or more offerings.Under this prospectus supplement, we are offering shares of our common stock having an aggregate offering price of up to $459,972,480 from time to If the information contained in this prospectus supplement differs or varies from the information contained in any document incorporated byreference herein that was filed with the SEC before the date of this prospectus supplement, you should rely on the information set forth in thisprospectus supplement. If any statement in one of these documents is inconsistent with a statement in another document having a later date (forexample, a subsequently filed document deemed incorporated by reference in this prospectus supplement), the statement in the document having the We have not, and the sales agent has not, authorized anyone to provide you with information that is in addition to or different from that containedor incorporated by reference in this p