FORM 3 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
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1. Name and Address of Reporting Person *
SEIDENBERG BETH C

(Last) (First) (Middle)
C/O LATIGO BIOTHERAPEUTICS, INC.
1300 RANCHO CONEJO BLVD., SUITE 305

(Street)
THOUSAND OAKS CA 91320

(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
08/06/2026
3. Issuer Name and Ticker or Trading Symbol
Latigo Biotherapeutics, Inc. [ LTGO ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director X 10% Owner
Officer (give title below) Other (specify below)
5. If Amendment, Date of Original Filed (Month/Day/Year)
6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock 429,553
I
See footnote (1)
Common Stock 46,855
I
See footnote (2)
Common Stock 27,956
I
See footnote (3)
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4) 2. Date Exercisable and Expiration Date (Month/Day/Year) 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 6. Nature of Indirect Beneficial Ownership (Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Series Seed Convertible Preferred Stock   (4)   (4) Common Stock 938,979 (4) I See footnote (1)
Series A Convertible Preferred Stock   (4)   (4) Common Stock 3,547,842 (4) I See footnote (1)
Series A-2 Convertible Preferred Stock   (4)   (4) Common Stock 1,027,635 (4) I See footnote (1)
Series A-2 Convertible Preferred Stock   (4)   (4) Common Stock 3,464,072 (4) I See footnote (2)
Series B Convertible Preferred Stock   (4)   (4) Common Stock 1,484,401 (4) I See footnote (2)
Series A-2 Convertible Preferred Stock   (4)   (4) Common Stock 2,066,857 (4) I See footnote (3)
Convertible Promissory Note   (5)   (5) Common Stock 165,519 (5) I See footnote (2)
Explanation of Responses:
1. Shares held directly by Westlake BioPartners Fund I, L.P. (Fund I). The general partner of Fund I is Westlake BioPartners GP I, LLC (GP I). GP I may be deemed to share voting and dispositive power with regard to the shares held directly by Fund I. The Reporting Person is the sole managing director of GP I and has voting and dispositive power over the shares held by Fund I. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
2. Shares held directly by Westlake BioPartners Fund II, L.P. (Fund II). The general partner of Fund II is Westlake BioPartners GP II, LLC (GP II). GP II may be deemed to share voting and dispositive power with regard to the shares held directly by Fund II. The Reporting Person is the sole managing director of GP II and has voting and dispositive power over the shares held by Fund II. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
3. Shares held directly by Westlake BioPartners Opportunity Fund I, L.P. (Opportunity Fund). The general partner of Opportunity Fund is Westlake BioPartners Opportunity GP I, LLC (Opportunity GP). Opportunity GP may be deemed to share voting and dispositive power with regard to the shares held directly by Opportunity Fund. The Reporting Person is the sole managing director of Opportunity GP and has voting and dispositive power over the shares held by Opportunity Fund. The Reporting Person disclaims Section 16 beneficial ownership of the shares reported herein except to the extent of her pecuniary interest therein, if any, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of any of the reported shares for purposes of Section 16 or any other purpose.
4. Each share of Series Seed Convertible Preferred Stock, Series A Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the "Preferred Stock") will automatically convert 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.
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.
/s/ Sabrina Nieder, Attorney-in-Fact 08/06/2026
** Signature of Reporting Person Date
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.
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ATTACHMENTS / EXHIBITS

ATTACHMENTS / EXHIBITS

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