BridgeBio Oncology Therapeutics Inc美股招股说明书(2026-06-22版)

This prospectus supplement no. 8 (this “Prospectus Supplement”) amends and supplements the prospectus dated September10, 2025 (as may besupplemented or amended from time to time, the “Prospectus”), which forms part of our Registration Statement on Form S-1 (Registration StatementNo.333-289940), as amended by the Post-Effective Amendment No.1 thereto (Registration Statement No.333-289940). This Prospectus Supplement isbeing filed to update and supplement the information included or incorporated by reference in the Prospectus with the information contained in theattached Current Report on Form 8-K, filed with the Securities and Exchange Commission (the “Securities and Exchange Commission”) on June22,2026 (the “Form 8-K”). Accordingly, we have attached the Form 8-K to this Prospectus Supplement. This Prospectus Supplement updates and supplements the information in the Prospectus and is not complete without, and may not be delivered orutilized except in combination with, the Prospectus, including any amendments or supplements thereto. This Prospectus Supplement should be read inconjunction with the Prospectus, and if there is any inconsistency between the information in the Prospectus and this Prospectus Supplement, you shouldrely on this Prospectus Supplement. Our common stock, par value $0.0001 per share (“Common Stock”) is listed on Nasdaq Global Market (“Nasdaq”) under the symbol “BBOT”. OnJune18, 2026, the closing price of our Common Stock as reported on Nasdaq was $7.56 per share. We are an “emerging growth company” as that term is defined under the federal securities laws and, as such, are subject to certain reducedpublic company reporting requirements. Investing in our securities involves risks that are described in the “Risk Factors” section beginning on page 10 of theProspectus. Neither the SEC nor any state securities commission has approved or disapproved of the securities to be issued under this prospectus ordetermined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense. UNITED STATESSECURITIES AND EXCHANGE COMMISSIONWASHINGTON, D.C. 20549 FORM 8-K CURRENT REPORTPursuant to Section 13 or 15(d)of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported): June 16, 2026 BridgeBio Oncology Therapeutics, Inc.(Exact name of Registrant as Specified in Its Charter) 39-3690783(IRS EmployerIdentification No.) 001-41955(CommissionFile Number) Delaware(State or Other Jurisdictionof Incorporation) 256 E. Grand Avenue, Suite 104South San Francisco, CA 94080(Address of principal executive offices, including zip code) (650) 405-4770(Telephone number, including area code, of agent for service) (Former name or former address, if changed since last report.) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of thefollowing provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section12(b) of the Act: Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of thischapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company☒ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with anynew or revised financial accounting standards provided pursuant to Section13(a) of the Exchange Act.☐ Departure of Director or Certain Officers; Election of Directors; Appointment of Certain Officers; CompensatoryArrangements of Certain Officers. On June16, 2026, Michelle Doig notified BridgeBio Oncology Therapeutics, Inc. (the “Company”), of her resignation as a member of the Board ofDirectors of the Company (the “Board”) upon the completion of her term as a ClassI director, effective as of June16, 2026, the date of the Company’s2026 Annual Meeting of Stockholders (the “Annual Meeting”). Ms.Doig’s resignation was not due to any disagreement with the Company on anymatter relating to the Company’s operations, policies or practices. Item 5.07.Submission of Matters to a Vote of Security Holders. The proposals set forth below were submitted to the stockholders at the Annual Meeting held on June16, 2026, with each such proposal described in theCompany’s definitive proxy statement filed with the Securities and Exchange Commission on April28, 2026 (the “Proxy Statement”). The number of shares of common stock entitled to vote at the Annual Meeting was 80,112,725. The nu