Erasca美股招股说明书(2026-07-13版)

$500,000,000 Common stock We are offering $500,000,000 of shares of our common stock, $0.0001 par value per share. Our common stock is listed on the Nasdaq Global Select Market under the symbol “ERAS.” On July10, 2026,the last reported sale price for our common stock on the Nasdaq Global Select Market was $18.53 per share ofcommon stock. We are an “emerging growth company” as that term is used in the Jumpstart Our Business Startups Act of 2012and, as such, have elected to comply with certain reduced public company disclosure and reportingrequirements. We have granted the underwriters an option to purchase up to an additional $75,000,000of shares of commonstock from us at the public offering price, less underwriting discounts and commissions, within 30 days from thedate of this prospectus supplement. Investing in our common stock involves a high degree of risk. See “Risk factors” beginning on page S-5of this prospectus supplement, on page 5 of the accompanying prospectus and the documentsincorporated by reference into this prospectus supplement and the accompanying prospectus. Neither the Securities and Exchange Commission nor any state securities commission has approved ordisapproved of these securities or determined if this prospectus supplement or the accompanyingprospectus is truthful or complete. Any representation to the contrary is a criminal offense. The underwriters expect to deliver the shares of common stock to purchasers on or about, 2026. , 2026 Table of Contents Table of contentsProspectus supplement About this prospectus supplementProspectus supplement summaryRisk factorsCautionary note regarding forward-looking statementsUse of proceedsDilutionMaterial U.S. federal income tax consequences to non-U.S. holdersUnderwritingLegal mattersExpertsWhere you can find more information; incorporation by reference Prospectus ABOUT THIS PROSPECTUSWHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCETHE COMPANYRISK FACTORSCAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSUSE OF PROCEEDSDESCRIPTION OF CAPITAL STOCK DESCRIPTION OF DEBT SECURITIES DESCRIPTION OF OTHER SECURITIES GLOBAL SECURITIES PLAN OF DISTRIBUTION LEGAL MATTERS EXPERTS Table of Contents About this prospectus supplement This prospectus supplement and the accompanying prospectus dated July13, 2026 are part of a registration statement that we filed withthe Securities and Exchange Commission (SEC), utilizing a “shelf” registration process. This prospectus supplement and theaccompanying prospectus relate to the offer by us of shares of our common stock to certain investors. We provide information to youabout this offering of shares of our common stock in two separate documents that are bound together: (1)this prospectus supplement,which describes the specific details regarding this offering; and (2)the accompanying prospectus, which provides general information,some of which may not apply to this offering. Generally, when we refer to this “prospectus,” we are referring to both documents combined.If information in this prospectus supplement is inconsistent with the accompanying prospectus, you should rely on this prospectussupplement. However, if any statement in one of these documents is inconsistent with a statement in another document having a laterdate—for example, a document incorporated by reference in this prospectus supplement or the accompanying prospectus—the statementin the document having the later date modifies or supersedes the earlier statement as our business, financial condition, results ofoperations and prospects may have changed since the earlier dates. You should read this prospectus supplement, the accompanyingprospectus, the documents and information incorporated by reference in this prospectus supplement and the accompanying prospectus,and any free writing prospectus that we have authorized for use in connection with this offering when making your investment decision.You should also read and consider the information in the documents we have referred you to under the headings “Where you can findmore information; incorporation by reference.” You should rely only on information contained in or incorporated by reference into this prospectus supplement and the accompanyingprospectus or any free writing prospectus prepared by or on behalf of us or to which we have referred you. We have not, and theunderwriters have not, authorized anyone to provide you with information that is different. We are offering to sell and seeking offers to buyshares of our common stock only in jurisdictions where offers and sales are permitted. The information contained in this prospectussupplement, the accompanying prospectus, the documents and information incorporated by reference in this prospectus supplement andthe accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering areaccurate only as of their respective dates, regardless of the time of deliver