Common Stock

BridgeBio Oncology Therapeutics, Inc.

256 E Grand Avenue, South San Fancisco, CA, 94080

Helix Holdings II LLC ("Sponsor"), Cormorant Private Healthcare Fund III, LP ("Fund III"), Cormorant Private Healthcare GP III, LLC ("GP III"), Cormorant Private Healthcare Fund V, LP ("Fund V"), Cormorant Private Healthcare GP V, LLC ("GP V"), Cormorant Global Healthcare Master Fund, LP ("Master Fund"), Cormorant Global Healthcare GP, LLC ("Global GP"), and Bihua Chen (collectively, the "Reporting Persons").

c/o Cormorant Asset Management, LP, 200 Clarendon Street, 52nd Floor, Boston, MA, 02116.

The principal occupation of Ms. Chen is Investor. Ms. Chen also serves as a director of the Issuer. The principal business of each of the Sponsor, Fund III, GP III, Fund V, GP V, Master Fund, and Global GP is investing in securities. Cormorant Asset Management, LP serves as the investment manager to the Master Fund. Cormorant Asset Management, LP serves as the investment manager to Fund III, Fund V, and Master Fund. GP III is the general partner of Fund III; GP V is the general partner of Fund V; and Global GP is the general partner of the Master Fund. Bihua Chen serves as the managing member of GP III, GP V, and Global GP, and as the general partner of Cormorant Asset Management, LP. Additionally, Ms. Chen is the manager of the Sponsor.

During the last five years, the Reporting Persons have not been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of which such person was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Sponsor is a limited liability company formed under the laws of the Cayman Islands. Fund III is a limited partnership organized under the laws of the State of Delaware. GP III is a limited liability company organized under the laws of the State of Delaware. Fund V is a limited partnership organized under the laws of the State of Delaware. GP V is a limited liability company organized under the laws of the State of Delaware. Master Fund is a limited partnership organized under the laws of the State of Delaware. Global GP is a limited liability company organized under the laws of the State of Delaware. Bihua Chen is citizen of the United States.

Item 5 is hereby amended and restated in its entirety as follows: The information set forth in the facing pages of this Schedule 13D with respect to the beneficial ownership of each Reporting Person is incorporated by reference into this Item 5. The aggregate number of shares of Common Stock owned by each Reporting Person is set forth on rows 7 through 11 and row 13 of the cover pages of this Amendment and is incorporated herein by reference. The percentage of the Common Stock held by each Reporting Person is based on an aggregate of 80,107,104 shares of Common Stock outstanding as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the U.S. Securities and Exchange Commission on May 12, 2026.

For each Reporting Person, the number of shares as to which there is sole power to vote or to direct the vote, shared power to vote or to direct the vote, sole power to dispose or to direct the disposition, or shared power to dispose or to direct the disposition are set forth on rows 7 through 11 and row 13 of the cover pages of this Amendment and are incorporated herein by reference. With respect to Bihua Chen, excludes 31,675 shares of Common Stock underlying unvested stock options.

Except for the transactions described in Items 4 and 6 of this Amendment and as described below, the Reporting Persons have not engaged in any transaction during the past 60 days involving the Common Stock of the Issuer. On June 16, 2026, as consideration for her service as a director of the Issuer, Bihua Chen was granted 31,675 stock options to purchase 31,675 shares of Common Stock at an exercise price of $7.73. Such options are unvested and will vest in full upon the earlier of (i) the first anniversary of the date of grant or (ii) the date of the Issuer's next annual meeting of stockholders following the date of grant, subject to Ms. Chen's continued service to the Issuer through the applicable vesting date.

To the best knowledge of the Reporting Persons, no one other than the Reporting Persons, or the affiliates of the Reporting Persons, is known to have the right to receive, or the power to direct the receipt of, dividends from, or proceeds from the sale of, the Common Stock reported herein as beneficially owned by the Reporting Persons.

Not applicable.