On August 11, 2025 (the "Closing Date"), BridgeBio Oncology Therapeutics, Inc., a Delaware corporation ("Issuer" or the "Company") consummated the previously announced business combination transactions (the "Closing") pursuant to that certain Business Combination Agreement, dated February 28, 2025 (as amended by Amendment No. 1 thereto, dated June 17, 2025, and as may be further amended, restated, supplemented, or otherwise modified from time to time, the "Business Combination Agreement"), by and among Helix Acquisition Corp. II, a Delaware corporation (the former name of the Issuer, "Helix"), Helix II Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of Helix ("Merger Sub"), and TheRas, Inc. (previously d/b/a BridgeBio Oncology Therapeutics), a Delaware corporation ("Old BBOT"). Pursuant to the Business Combination Agreement, (1) Helix domesticated as a Delaware corporation; (2) Merger Sub merged with and into Old BBOT, with Old BBOT surviving the merger as a wholly-owned subsidiary of the Issuer (the "Merger"), and (3) the parties consummated the other transactions contemplated by the Business Combination Agreement and documents related thereto (such transactions collectively, the "Business Combination"). In connection with the Closing and on the Closing Date, the Issuer changed its name to BridgeBio Oncology Therapeutics, Inc. and Old BBOT changed its name to BridgeBio Oncology Sub, Inc. As a result of the Closing, BBIO LLC acquired an aggregate of 13,878,554 shares of common stock, par value $0.0001 ("Common Stock") per share of the Company, consisting of (i) 13,805,126 shares of Common Stock and (ii) options to purchase 73,428 shares of Common Stock issuable upon the exercise of vested Company options (collectively, the "Shares"). The issuance of shares of Common Stock to the former equity holders of Old BBOT was registered with the U.S. Securities and Exchange Commission (the "SEC") on a Registration Statement on Form S-4 (Reg. No. 333-288222). The foregoing description of the Business Combination Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Business Combination Agreement, which is filed as Exhibit 99.2 to this Schedule 13D and incorporated herein by reference.

The information contained in Item 3 is incorporated herein by reference. Lock-Up Agreement Pursuant to the terms of the Business Combination Agreement, the Reporting Persons agreed, subject to certain customary exceptions, not to (i) sell, offer to sell, contract or agree to sell, pledge or otherwise dispose of, directly or indirectly, any shares of Common Stock held by them (such shares, together with any securities convertible into or exchangeable for or representing the rights to receive shares of Common Stock if any, acquired during the Lock-Up Period (as defined below), the "Lock-Up Shares"), (ii) enter into a transaction that would have the same effect, (iii) enter into any swap, hedge or other arrangement that transfers to another, in whole or in part, any of the economic consequences of ownership of the Lock-Up Shares or otherwise or engage in any short sales or other arrangement with respect to the Lock-Up Shares or (iv) publicly announce any intention to effect any transaction specified in clause (i) or (ii) until the date that is one year after the later of (x) the filing of the Form 10 Information (as defined in Rule 144(i)(3) of the Securities Act of 1933, as amended) with the U.S. Securities and Exchange Commission (the "SEC") and (y) the Closing Date (the "Lock-Up Period"). The Lock-Up Agreement is also incorporated into the Issuer's Bylaws and applies to all shares received in the merger of Merger Sub with and into Old BBOT, with Old BBOT surviving the merger as a wholly-owned subsidiary of Helix (the "Merger"), or upon the exercise of equity awards assumed by the Issuer in connection with the Business Combination. Permitted transfers include, among others, transfers to affiliates, family members, trusts, or in connection with estate planning. In addition, if the Issuer's board of directors waives or repeals the lock-up for any holder, it must also waive or repeal the lock-up for all similarly situated holders. Amended and Restated Registration Rights Agreement On August 11, 2025, in connection with the closing of the Business Combination, the Issuer and certain securityholders, including the Reporting Person, entered into an Amended and Restated Registration Rights Agreement (the "Registration Rights Agreement"). Pursuant to the Registration Rights Agreement, the Reporting Person was granted certain demand, shelf, and "piggyback" registration rights with respect to its shares of Common Stock, subject to customary conditions and limitations. The Registration Rights Agreement also restricts the ability of the Reporting Person to transfer its shares for a period following the closing of the Business Combination, as specified in the Company's Bylaws, subject to certain permitted transfers. The Registration Rights Agreement also provides for customary indemnification and contribution provisions. The foregoing descriptions of the Lock-Up Agreement and Amended and Restated Registration Rights Agrement contained herein do not purport to be complete and are qualified in their entirety by reference to the full text of such agreements, which are attached hereto as Exhibits 99.3 and 99.4, respectively, and are incorporated herein by reference.

Exhibit 99.1: Joint Filing Agreement (filed herewith). Exhibit 99.2: Business Combination Agreement, by and among Helix Acquisition Corp. II, TheRas, Inc. and Helix II Merger Sub, Inc., dated as of February 28, 2025 (incorporated by reference to the Company's proxy statement/prospectus filed on July 9, 2025). Exhibit 99.3: Amendment No. 1 to Business Combination Agreement, by and among Helix Acquisition Corp. II, TheRas, Inc. and Helix Merger Sub, Inc., dated as of June 17, 2025 (incorporated by reference to the Company's proxy statement/prospectus filed on July 9, 2025). Exhibit 99.4: Lock-Up Agreement, dated as of August 11, 2025, by and between Helix Acquisition Corp. II, Helix Holdings II, LLC, certain investment vehicles of Cormorant Asset Management, LP, certain existing shareholders of TheRas, Inc., and other persons and entities (incorporated by reference to Exhibit 10.3 to the Current Report on Form 8-K filed by the Company on August 12, 2025). Exhibit 99.5: Amended and Restated Registration Rights Agreement, dated as of August 11, 2025, by and between the Company, Helix Holdings II, LLC, certain investment vehicles of Cormorant Asset Management, LP, entities affiliated with BridgeBio Pharma, Inc., certain former stockholders of TheRas, Inc., and other persons and entities (incorporated by reference to Exhibit 10.1 to the Current Report on Form 8-K filed by the Company on August 12, 2025).