BridgeBio Oncology Therapeutics Inc 美股招股说明书（2026年4月23日版）

This prospectus supplement no. 5 (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). This Prospectus Supplement is being filed to update and supplement the information included or incorporated by reference in theProspectus with the information contained in the attached Current Report on Form 8-K, filed with the Securities and Exchange Commission (the 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 in Our common stock, par value $0.0001 per share (“Common Stock”) is listed on Nasdaq Global Market (“Nasdaq”) under the symbol “BBOT”. OnApril21, 2026, the closing price of our Common Stock as reported on Nasdaq was $9.46 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. The date of this Prospectus Supplement is April22, 2026. UNITED STATESSECURITIES AND EXCHANGE COMMISSION FORM 8-K CURRENT REPORTPursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934Date of Report (Date of earliest event reported): April 20, 2026 BridgeBio Oncology Therapeutics, Inc.(Exact name of Registrant as Specified in Its Charter) 39-3690783(IRS EmployerIdentification No.) 001-41955(CommissionFile Number) 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)) 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). 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.☐ Item 5.02Departure of Director or Certain Officers; Election of Directors; Appointment of Certain Officers; CompensatoryArrangements of Certain Officers. Appointment Chief Executive Officer and Director On April20, 2026, the Board of Directors (the “Board”) of BridgeBio Oncology Therapeutics, Inc. (the “Company”) approved the appointment of PedroBeltran, Ph.D., as the Company’s President and Chief Executive Officer (“CEO”) (and as the Company’s principal executive officer), effective Additionally, on April20, 2026, Dr.Wallace resigned from his position as a member of the Board and as a ClassIII director, and the Board appointedDr.Beltran as a ClassIII director to fill the vacancy created by Dr.Wallace’s resignation, effective immediately. It is expected that Dr.Wallace willcontinue to serve as an advisor to the Company following his term as President and CEO. Dr.Wallace’s resignation was not the result of any Dr.Beltran, age 55, served as Chief Scientific Officer of the Company (including the Company’s predecessor, TheRas, Inc.) since April 2024 until hisappointment as President and CEO. Previously, Dr.Beltran served as Chief Scientific Officer of BridgeBio Pharma, Inc. (Nasdaq: BBIO) fromJuly2023 to April 2024, and as Senior Vice President of Biology from July2020 to July2023. From November 2017 to July 2020, Dr.Beltran wasSenior Vice President, Head of Biology at UNITY Biotechnology and from 2003 to 2017 held various roles at Amgen, Inc., including ExecutiveDirector of Oncology Research. He has led multiple Investigational New Drug application submissions, authored more than 50 peer-reviewed articles,presented at numerous national and international scientific conferences, and holds diverse patents for the treatment of malignant diseases. Dr.Beltran Dr.Beltran is employed on an at-will basis pursuant to an employment agreement with the Company. Dr.Beltran is entitled to receive an annual basesalary and an annual target bonus equal to a