RAPT Therapeutics Inc美股招股说明书(2025-10-22版)

Our common stock is listed on the Nasdaq Global Market under the trading symbol “RAPT.” On October21, 2025, the last reported sale price of ourcommon stock was $33.53 per share. We are a “smaller reporting company” as defined under the federal securities laws and, as such, have elected to comply with certain reduced publiccompany reporting requirements for this prospectus and the documents incorporated by reference herein and may elect to comply with reduced publiccompany reporting requirements in future filings. Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertaintiesdescribed in the section titled “Risk Factors” on pageS-7 of this prospectus supplement, page8 of the accompanyingprospectus and under similar headings in the documents incorporated by reference into this prospectus supplement andthe accompanying prospectus. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities ordetermined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense. Underwriting discounts and commissions(1)Proceeds to us, before expenses (1)See the section titled “Underwriting” for additional information regarding compensation payable to the underwriters. We have granted the underwriters an option for a period of 30 days to purchase up to an additional 1,250,000 shares of common stock at the publicoffering price, less the underwriting discounts and commissions. The underwriters expect to deliver the shares of common stock against payment on or about October 23, 2025. Joint Bookrunning Managers LifeSci Capital H.C. Wainwright & Co. Clear Street Table of Contents TABLE OF CONTENTS Prospectus Supplement ABOUT THIS PROSPECTUS SUPPLEMENTPROSPECTUS SUPPLEMENT SUMMARYSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSRISK FACTORSUSE OF PROCEEDSDILUTIONMATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCESUNDERWRITINGLEGAL MATTERSEXPERTSWHERE YOU CAN FIND ADDITIONAL INFORMATIONINCORPORATION OF CERTAIN INFORMATION BY REFERENCE Prospectus ABOUT THIS PROSPECTUSPROSPECTUS SUMMARYRISK FACTORSSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS USE OF PROCEEDSDESCRIPTION OF CAPITAL STOCKDESCRIPTION OF DEBT SECURITIESDESCRIPTION OF WARRANTSLEGAL OWNERSHIP OF SECURITIESPLAN OF DISTRIBUTIONLEGAL MATTERSEXPERTSWHERE YOU CAN FIND ADDITIONAL INFORMATIONINCORPORATION OF CERTAIN INFORMATION BY REFERENCE Table of Contents ABOUT THIS PROSPECTUS SUPPLEMENT This prospectus supplement and the accompanying prospectus are part of a “shelf” registration statement onFormS-3(FileNo.333-273910)thatweinitially filed with the Securities and Exchange Commission (the “SEC”) on August11, 2023, and that was declared effective by the SEC on August17,2023.This document consists of two parts. The first part is this prospectus supplement, which describes the specific terms of this offering and also addsto and updates the information contained in the accompanying prospectus and the documents incorporated by reference into this prospectus supplementand the accompanying prospectus. The second part, the accompanying prospectus, gives more general information, some of which may not apply to thisoffering. If there is an inconsistency between the information contained in this prospectus supplement, on the one hand, and the information contained inthe accompanying prospectus or any document incorporated by reference prior to the date of this prospectus supplement, on the other hand, you shouldrely on the information in this prospectus supplement. In addition, to the extent any information incorporated by reference in this prospectus supplementor the accompanying prospectus from a filing we make with the SEC after the date of this prospectus supplement adds to, updates or changesinformation contained in this prospectus supplement, the accompanying prospectus or an earlier filing we made with the SEC that is incorporated byreference in this prospectus supplement or the accompanying prospectus, the information in such later filing shall be deemed to modify, update andsupersede such information in this prospectus supplement, the accompanying prospectus or the earlier filing with the SEC. Generally, when we refer tothe prospectus, we are referring to this prospectus supplement and the accompanying prospectus combined. We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that isincorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose ofallocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, suchrepresentations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants