ImageneBio Inc美股招股说明书(2026-05-07版)

2,508,337 Shares of Common Stock This prospectus supplement supplements the prospectus dated April2, 2026 (the “Prospectus”), which forms a part of our registration statementon Form S-1 (No. 333-290108), as amended. This prospectus supplement is being filed to update and supplement the information in the Prospectus withcertain information contained in our Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on May7, 2026 (the“Quarterly Report”). Accordingly, we have attached the Quarterly Report in relevant part to this prospectus supplement. The Prospectus and this prospectus supplement relate to the proposed offer and resale or other disposition from time to time by the sellingstockholders identified in this prospectus of 2,508,337 shares of common stock, par value $0.001 per share, (the “Common Stock”) of ImageneBio, Inc. Our Common Stock is listed on the Nasdaq Capital Market under the ticker symbol “IMA.” On May6, 2026, the last reported sales price of ourCommon Stock was $6.08 per share. This prospectus supplement should be read in conjunction with the Prospectus, including any amendments or supplements to it, which is to bedelivered with this prospectus supplement. This prospectus supplement is qualified by reference to the Prospectus, including any amendments orsupplements thereto, except to the extent that the information provided by this prospectus supplement supersedes information contained in theProspectus. This prospectus supplement is not complete without, and may not be delivered or used except in conjunction with, the Prospectus, including anyamendments or supplements to it. Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertaintiesdescribed in the section titled “Risk Factors” beginning on page 6 of the Prospectus, and under similar headings in anyamendments or supplements to the Prospectus. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, orpassed upon the accuracy or adequacy of this prospectus supplement. Any representation to the contrary is a criminal offense.