Erasca Inc美股招股说明书(2026-01-22版)

Common stock We are offering 22,500,000 shares of our common stock. Our common stock is listed on the Nasdaq Global Select Market under the symbol “ERAS.” On January21, 2026, the last reported saleprice for our common stock on the Nasdaq Global Select Market was $10.05 per share of common stock. We are an “emerging growth company” as that term is used in the Jumpstart Our Business Startups Act of 2012 and, as such, haveelected to comply with certain reduced public company disclosure and reporting requirements. We have granted the underwriters an option to purchase up to an additional 3,375,000 shares of common stock from us at the publicoffering price, less underwriting discounts and commissions, within 30 days from the date of this prospectus supplement. Investing in our common stock involves a high degree of risk. See “Risk factors” beginning on page S-4 of this prospectussupplement, on page 5 of the accompanying prospectus and the documents incorporated by reference into this prospectussupplement and the accompanying prospectus. Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Anyrepresentation to the contrary is a criminal offense. The underwriters expect to deliver the shares of common stock to purchasers on or about January23, 2026. J.P. Morgan MorganStanley Jefferies Evercore ISI January21, 2026 Table of Contents TABLE OF CONTENTS PageProspectus supplementABOUT THIS PROSPECTUS SUPPLEMENTS-iiPROSPECTUS SUPPLEMENT SUMMARYS-1RISK FACTORSS-4CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTSS-6USE OF PROCEEDSS-7DILUTIONS-8MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES TO NON-U.S. HOLDERSS-10UNDERWRITINGS-14LEGAL MATTERSS-29EXPERTSS-29WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCES-30ProspectusABOUT THIS PROSPECTUS1WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE2THE COMPANY4RISK FACTORS5CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS6USE OF PROCEEDS7DESCRIPTION OF CAPITAL STOCK7DESCRIPTION OF DEBT SECURITIES13DESCRIPTION OF WARRANTS21DESCRIPTION OF UNITS23GLOBAL SECURITIES24PLAN OF DISTRIBUTION28LEGAL MATTERS30EXPERTS30 Table of Contents About this prospectus supplement This prospectus supplement and the accompanying prospectus dated August22, 2025 are part of a registration statement that we filedwith the 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 o