Sec Form 3 Filing - Foresite Capital Management V, LLC @ Latigo Biotherapeutics, Inc. - 2026-08-06

FORM 3 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

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1. Name and Address of Reporting Person Foresite Capital Management V, LLC 2. Issuer Name and Ticker or Trading Symbol Latigo Biotherapeutics, Inc. [ LTGO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O FORESITE CAPITAL MANAGEMENT, 9200 SUNSET BOULEVARD, SUITE PH1 3. Date of Earliest Transaction (MM/DD/YY) 08/06/2026 (Street) WEST HOLLYWOOD, CA90069 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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

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 Series A-2 Convertible Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 3,117,664 I See footnote ( 2 ) Series B Convertible Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 445,320 I See footnote ( 2 ) Series A-2 Convertible Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 1,125,823 I See footnote ( 3 ) Series B Convertible Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 742,201 I See footnote ( 3 ) Series A-2 Convertible Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 3,117,664 I See footnote ( 4 ) Series B Convertible Preferred Stock ( 1 ) ( 1 ) ( 1 ) Common Stock 296,880 I See footnote ( 4 ) Convertible Promissory Note ( 5 ) ( 5 ) ( 5 ) Common Stock 195,776 I See footnote ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Foresite Capital Management V, LLC C/O FORESITE CAPITAL MANAGEMENT 9200 SUNSET BOULEVARD, SUITE PH1 WEST HOLLYWOOD, CA90069 X Foresite Capital Fund V, L.P. C/O FORESITE CAPITAL MANAGEMENT 9200 SUNSET BOULEVARD, SUITE PH1 WEST HOLLYWOOD, CA90069 X Foresite Capital Opportunity Fund V, L.P. C/O FORESITE CAPITAL MANAGEMENT 9200 SUNSET BOULEVARD, SUITE PH1 WEST HOLLYWOOD, CA90069 X Foresite Capital Opportunity Management V, LLC C/O FORESITE CAPITAL MANAGEMENT 9200 SUNSET BOULEVARD, SUITE PH1 WEST HOLLYWOOD, CA90069 X Foresite Capital Fund VI LP C/O FORESITE CAPITAL MANAGEMENT 9200 SUNSET BOULEVARD, SUITE PH1 WEST HOLLYWOOD, CA90069 X Foresite Capital Management VI LLC C/O FORESITE CAPITAL MANAGEMENT 9200 SUNSET BOULEVARD, SUITE PH1 WEST HOLLYWOOD, CA90069 X Signatures FORESITE CAPITAL MANAGEMENT V, LLC, By: /s/ James B. Tananbaum, Managing Member 08/06/2026 Signature of Reporting Person Date FORESITE CAPITAL FUND V, L.P., By: Foresite Capital Management V, LLC, Its: General Partner, By: /s/ James B. Tananbaum, Managing Member 08/06/2026 Signature of Reporting Person Date FORESITE CAPITAL OPPORTUNITY MANAGEMENT V, LLC, By: /s/ James B. Tananbaum, Managing Member 08/06/2026 Signature of Reporting Person Date FORESITE CAPITAL OPPORTUNITY FUND V, L.P., By: Foresite Capital Opportunity Management V, LLC, Its: General Partner, By: /s/ James B. Tananbaum, Managing Member 08/06/2026 Signature of Reporting Person Date FORESITE CAPITAL MANAGEMENT VI, LLC, By: /s/ James B. Tananbaum, Managing Member 08/06/2026 Signature of Reporting Person Date FORESITE CAPITAL FUND VI LP, By: Foresite Capital Management VI, LLC, Its: General Partner, By: /s/ James B. Tananbaum, Managing Member 08/06/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Each share of Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the "Preferred Stock") will convert automatically into 1 share of Common Stock upon the closing of the Issuer's initial public offering without payment of further consideration. Share numbers give effect to such conversion. The Preferred Stock has no expiration date. ( 2 )The securities are held of record by Foresite Capital Fund V, L.P. (Fund V). Foresite Capital Management V, LLC (FCM V) is the general partner of Fund V and may be deemed to have sole voting and dispositive power over the securities held by Fund V. James B. Tananbaum (Tananbaum) is the sole managing member of FCM V and may be deemed to have sole voting and dispositive power over the securities held by Fund V. Each of the Reporting Persons disclaims the existence of a "group" and disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. ( 3 ) The securities are held of record by Foresite Capital Fund VI LP (Fund VI). Foresite Capital Management VI, LLC (FCM VI) is the general partner of Fund VI and may be deemed to have sole voting and dispositive power over the securities held by Fund VI. Tananbaum is the sole managing member of FCM VI and may be deemed to have sole voting and dispositive power over the securities held by Fund VI. Each of the Reporting Persons disclaims the existence of a "group" and disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. ( 4 )The securities are held of record by Foresite Capital Opportunity Fund V, L.P. (Opportunity Fund V). Foresite Capital Opportunity Management V, LLC (FCOM V) is the general partner of Opportunity Fund V and may be deemed to have sole voting and dispositive power over the shares held by Opportunity Fund V. Tananbaum is the sole managing member of FCOM V and may be deemed to have sole voting and dispositive power over the securities held by Opportunity Fund V. Each of the Reporting Persons disclaims the existence of a "group" and disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein. ( 5 )Reflects a convertible note that is convertible into shares of Common Stock of the Issuer. The convertible note has a maturity date of June 17, 2027. The principal amount of the convertible note together with any accrued but unpaid interest will be automatically converted into shares of Common Stock of the Issuer upon the closing of the Issuer's initial public offering at a conversion price equal to the initial public offering price of the Issuer's Common Stock.

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).

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