Sec Form 4 Filing - Chen Bihua @ BridgeBio Oncology Therapeutics, Inc. - 2025-08-11

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Chen Bihua 2. Issuer Name and Ticker or Trading Symbol BridgeBio Oncology Therapeutics, Inc. [ BBOT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O HELIX ACQUISITION CORP. II, 200 CLARENDON STREET, 52ND FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 08/11/2025 (Street) BOSTON, MA02116 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 08/11/2025 M( 3 ) 4,172,126 A 4,681,126 I Via Helix Holdings II LLC ( 9 ) Common Stock 08/11/2025 D( 4 ) 152,940 D $ 0 4,528,186 I Via Helix Holdings II LLC ( 9 ) Common Stock 08/11/2025 A( 5 ) 760,496 A $ 10.7173 2,187,536 I Via Fund III ( 10 ) Common Stock 08/11/2025 A( 6 ) 639,110 A $ 10.7173 1,542,710 I Via Fund V ( 10 ) Common Stock 08/11/2025 A( 7 ) 5,598,425 A $ 10.7173 5,667,785 I Via Master Fund ( 10 ) Common Stock 08/11/2025 A( 8 ) 1,905,046 A 1,905,046 I Via Fund IV ( 10 ) Common Stock 08/11/2025 A( 8 ) 1,762,760 A 3,305,470 I Via Fund V ( 10 ) Common Stock 08/11/2025 A( 8 ) 284,571 A 5,952,356 I Via Master Fund ( 10 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Class B ordinary shares ( 2 ) 08/11/2025 D( 1 ) 307,874 ( 2 ) ( 2 ) Class A ordinary shares 307,874 $ 0 4,172,126 I See footnote ( 9 ) Class B ordinary shares ( 2 ) 08/11/2025 M( 3 ) 4,172,126 ( 2 ) ( 2 ) Class A ordinary shares 4,172,126 ( 3 ) 0 I See footnote ( 9 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Chen Bihua C/O HELIX ACQUISITION CORP. II 200 CLARENDON STREET, 52ND FLOOR BOSTON, MA02116 X X Signatures /s/ Bihua Chen 08/13/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )In connection with and prior to the closing of the business combination (the "Business Combination") between the Issuer (which was formerly known as Helix Acquisition Corp. II, "Helix") and TheRas, Inc. ("Legacy BBOT"), Helix Holdings II LLC (the "Sponsor") forfeited 307,874 Helix Class B ordinary shares for no consideration pursuant to the terms of the Sponsor Support Agreement dated February 28, 2025, between Sponsor, Helix, and Legacy BBOT (the "Sponsor Support Agreement"). ( 2 )The Helix Class B ordinary shares have no expiration date and automatically convert into Class A ordinary shares at the time of Helix's initial business combination as described under the heading "Description of Securities" in Helix's registration statement on Form S-1 (File No. 333-276591). ( 3 )In connection with and prior to the closing of the Business Combination, among other things, (i) each of Helix's Class B ordinary shares converted into one Helix Class A ordinary share, on a one-for-one basis, (ii) Helix migrated to and domesticated as a Delaware corporation in accordance with Section 388 of the Delaware General Corporation Law, as amended, and the Cayman Islands Companies Act (As Revised) (the "Domestication"), and (iii) as a result of the Domestication, each Class A ordinary share of Helix converted into one share of the Issuer's common stock, par value $0.0001 per share ("Common Stock"), on a one-for-one basis. ( 4 )In connection with and immediately prior to the closing of the Business Combination, the Sponsor forfeited 152,940 shares of Common Stock for no consideration, pursuant to the terms of the Sponsor Support Agreement. ( 5 )In connection with and immediately prior to the closing of the Business Combination, pursuant to the terms of a subscription agreement dated February 28, 2025 between Helix and Cormorant Asset Management, LP (the "Subscription Agreement"), Cormorant Private Healthcare Fund III, LP ("Fund III"), which is an investment vehicle managed by Cormorant Asset Management, LP, purchased from the Issuer 760,496 shares of Common Stock at a purchase price of $10.7173 per share. ( 6 )In connection with and immediately prior to the closing of the Business Combination, pursuant to the terms of the Subscription Agreement, Cormorant Private Healthcare Fund V, LP ("Fund V"), which is an investment vehicle managed by Cormorant Asset Management, LP, purchased from the Issuer 639,110 shares of Common Stock at a purchase price of $10.7173 per share. ( 7 )In connection with and immediately prior to the closing of the Business Combination, pursuant to the terms of the Subscription Agreement, Cormorant Global Healthcare Master Fund, LP ("Master Fund"), which is an investment vehicle managed by Cormorant Asset Management, LP, purchased from the Issuer 5,598,425 shares of Common Stock at a purchase price of $10.7173 per share. ( 8 )Upon the closing of the Business Combination, as contemplated by the terms of the Business Combination Agreement, dated as of February 28, 2025 (as amended, the "Business Combination Agreement"), by and among Helix, Legacy BBOT, and Helix Merger Sub, Inc., the owners of Legacy BBOT equity as of immediately prior to the closing, including Fund V, Master Fund, and Cormorant Private Healthcare Fund IV, LP ("Fund IV"), received as consideration therefor, shares of common stock of the Issuer. ( 9 )Sponsor is the record holder of the securities reported herein. Fund III, Fund V, and Master Fund are the members of Sponsor. Bihua Chen is the manager of Sponsor and has voting and investment discretion with respect to the shares held of record by Sponsor. Each of Fund III, Fund V, Master Fund and Ms. Chen disclaims any beneficial ownership of the securities held by Sponsor other than to the extent of any pecuniary interest she or it may have therein, directly or indirectly. ( 10 )Cormorant Asset Management, LP serves as the investment ma nager to Fund III, Fund IV, Fund V, and Master Fund (collectively, the "Cormorant Funds"). Cormorant Private Healthcare GP III, LLC ("GP III") is the general partner of Fund III; Cormorant Private Healthcare GP IV, LLC ("GP IV") is the general partner of Fund IV; Cormorant Private Healthcare GP V, LLC ("GP V") is the general partner of Fund V; and Cormorant Global Healthcare GP, LLC ("Global GP") is the general partner of the Master Fund. Bihua Chen serves as the managing member of GP III, GP IV, GP V, and Global GP, and as the general partner of Cormorant Asset Management, LP. Accordingly, Ms. Chen has voting and investment discretion with respect to the shares held by each of the Cormorant Funds and Cormorant Asset Management, LP. Ms. Chen disclaims any beneficial ownership of the securities held by each of the Cormorant Funds other than to the extent of any pecuniary interest she may have therein, directly or indirectly.

Remarks: Ms. Chen serves on the Board of Directors of the Issuer. Sponsor and the Cormorant Funds may be deemed to be directors by deputization as a result of the service of Ms. Chen.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.