# EDGAR Filing Document

**Accession Number:** 0001855502
**File Stem:** 0001193125-25-204935
**Filing Date:** 2025-9
**Character Count:** 15844
**Document Hash:** e0cbe7072b71a1daced239b612820d7b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-204935.hdr.sgml**: 20250916

**ACCESSION NUMBER**: 0001193125-25-204935

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20250912

**FILED AS OF DATE**: 20250916

**DATE AS OF CHANGE**: 20250916

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Belldegrun Arie
- **CENTRAL INDEX KEY:** 0001296549

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42831
- **FILM NUMBER:** 251317225

**MAIL ADDRESS:**
- **STREET 1:** UCLA SCHOOL OF MEDICINE
- **STREET 2:** 10833 LE CONTE 66-118 CHS BOX 951738
- **CITY:** LOS ANGELES
- **STATE:** CA
- **ZIP:** 9095-1738
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Vida Ventures GP III, L.L.C.
- **CENTRAL INDEX KEY:** 0001855502

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42831
- **FILM NUMBER:** 251317228

**BUSINESS ADDRESS:**
- **STREET 1:** 455 MARKET STREET, SUITE 1420
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94105
- **BUSINESS PHONE:** (424) 313-1550

**MAIL ADDRESS:**
- **STREET 1:** 455 MARKET STREET, SUITE 1420
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94105
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Vida Ventures Management Co. LLC
- **CENTRAL INDEX KEY:** 0001905615

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42831
- **FILM NUMBER:** 251317224

**BUSINESS ADDRESS:**
- **STREET 1:** 40 BROAD STREET
- **STREET 2:** SUITE 201
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109
- **BUSINESS PHONE:** 424-313-1550

**MAIL ADDRESS:**
- **STREET 1:** 40 BROAD STREET
- **STREET 2:** SUITE 201
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02109
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Vida Ventures III-A, L.P.
- **CENTRAL INDEX KEY:** 0001855503

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42831
- **FILM NUMBER:** 251317226

**BUSINESS ADDRESS:**
- **STREET 1:** 455 MARKET STREET, SUITE 1420
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94105
- **BUSINESS PHONE:** (424) 313-1550

**MAIL ADDRESS:**
- **STREET 1:** 455 MARKET STREET, SUITE 1420
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94105
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Vida Ventures III, L.P.
- **CENTRAL INDEX KEY:** 0001855504

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-42831
- **FILM NUMBER:** 251317227

**BUSINESS ADDRESS:**
- **STREET 1:** 455 MARKET STREET, SUITE 1420
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94105
- **BUSINESS PHONE:** (424) 313-1550

**MAIL ADDRESS:**
- **STREET 1:** 455 MARKET STREET, SUITE 1420
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94105
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** LB PHARMACEUTICALS INC
- **CENTRAL INDEX KEY:** 0001691082
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 575 MADISON AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10022
- **BUSINESS PHONE:** 917-450-6581

**MAIL ADDRESS:**
- **STREET 1:** 575 MADISON AVENUE
- **CITY:** NEW YORK
- **STATE:** NY
- **ZIP:** 10022

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** LB PHARMACEUTICALS INC.
- **DATE OF NAME CHANGE:** 20161129

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

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

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Vida Ventures GP III, L.L.C.<br><sub>(Last) (First) (Middle)</sub><br>10100 SANTA MONICA BOULEVARD<br>SUITE 1500<br><sub>(Street)</sub><br>LOS ANGELES, CA 90067<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-09-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>LB PHARMACEUTICALS INC [ LBRX ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Vida Ventures III, L.P.<br><sub>(Last) (First) (Middle)</sub><br>10100 SANTA MONICA BOULEVARD<br>SUITE 1500<br><sub>(Street)</sub><br>LOS ANGELES, CA 90067<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-09-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>LB PHARMACEUTICALS INC [ LBRX ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Vida Ventures III-A, L.P.<br><sub>(Last) (First) (Middle)</sub><br>10100 SANTA MONICA BOULEVARD<br>SUITE 1500<br><sub>(Street)</sub><br>LOS ANGELES, CA 90067<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-09-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>LB PHARMACEUTICALS INC [ LBRX ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Belldegrun Arie<br><sub>(Last) (First) (Middle)</sub><br>10100 SANTA MONICA BOULEVARD<br>SUITE 1500<br><sub>(Street)</sub><br>LOS ANGELES, CA 90067<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-09-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>LB PHARMACEUTICALS INC [ LBRX ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Vida Ventures Management Co. LLC<br><sub>(Last) (First) (Middle)</sub><br>10100 SANTA MONICA BOULEVARD<br>SUITE 1500<br><sub>(Street)</sub><br>LOS ANGELES, CA 90067<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2025-09-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>LB PHARMACEUTICALS INC [ LBRX ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2025-09-12 |  | C<sup>(1)</sup> |  | 547648 | A | <sup>(1)</sup> | 547648 | I | By Vida Ventures III, L.P.<sup>(2)(3)</sup> |
| Common Stock | 2025-09-12 |  | C<sup>(1)</sup> |  | 1262 | A | <sup>(1)</sup> | 1262 | I | By Vida Ventures III-A, L.P.<sup>(4)</sup> |
| Common Stock | 2025-09-12 |  | P |  | 332566 | A | $15.00 | 880214 | I | By Vida Ventures III, L.P.<sup>(2)(3)</sup> |
| Common Stock | 2025-09-12 |  | P |  | 767 | A | $15.00 | 2029 | I | By Vida Ventures III-A, L.P.<sup>(4)</sup> |
| Common Stock |  |  |  |  |  |  |  | 1434 | I | By Vida Ventures Management Co. LLC<sup>(5)</sup> |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Series C Preferred Stock | <sup>(1)</sup> | 2025-09-12 |  | C |  |  | 13302666 | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 547648 | $0 | 0 | I | By Vida Ventures III, L.P.<sup>(2)(3)</sup> |
| Series C Preferred Stock | <sup>(1)</sup> | 2025-09-12 |  | C |  |  | 30667 | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 1262 | $0 | 0 | I | By Vida Ventures III-A, L.P.<sup>(4)</sup> |

---

### Footnotes:

(1) Each share of Series C Preferred Stock has no expiration date and converted automatically into Common Stock immediately prior to the Issuer's initial public offering at a conversion ratio based upon the initial price per share to the public in the Issuer's initial public offering.

(2) These shares are held directly by Vida Ventures III, L.P. ("Vida III"). Vida Ventures GP III, L.L.C. ("Vida III GP") is the general partner of Vida III and may be deemed to have voting, investment, and dispositive power with respect to these securities. Arie Belldegrun, Helen Kim and Rajul Jain, are the members of the investment committee of Vida III GP (each, an "Investment Committee Member" and such committee, the "Investment Committee").

(3) (Continued from Footnote 2) The Investment Committee and each of the Investment Committee Members may be deemed to share voting, investment and dispositive power with respect to these securities. Vida III GP, the Investment Committee and each of the Investment Committee Members disclaims beneficial ownership of the securities held of record by Vida III, and this report shall not be deemed an admission that they are the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein, if any.

(4) These shares are held directly by Vida Ventures III-A, L.P. ("Vida III-A"). Vida III GP is the general partner of Vida III-A and may be deemed to have voting, investment, and dispositive power with respect to these securities. The Investment Committee and each of the Investment Committee Members may be deemed to share voting, investment and dispositive power with respect to these securities. Vida III GP, the Investment Committee and each of the Investment Committee Members disclaims beneficial ownership of the securities held of record by Vida III-A, and this report shall not be deemed an admission that they are the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein, if any.

(5) These shares are held directly by Vida Ventures Management Co., LLC ("Vida Management"). Each Investment Committee Member (as defined below) disclaims beneficial ownership of the securities held of record by Vida Management, and this report shall not be deemed an admission that they are the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their pecuniary interest therein, if any.

**Signature:** VIDA VENTURES GP III, L.L.C., By: /s/ Jean-Philippe Kouakou-Zebouah, its Managing Member  
**Date:** 2025-09-16

**Signature:** VIDA VENTURES III, L.P., By: Vida Ventures GP III, L.L.C., its general partner, By: /s/ Jean-Philippe Kouakou-Zebouah, its Managing Member  
**Date:** 2025-09-16

**Signature:** VIDA VENTURES III-A, L.P., By: Vida Ventures GP III, L.L.C., its general partner, By: /s/ Jean-Philippe Kouakou-Zebouah, its Managing Member  
**Date:** 2025-09-16

**Signature:** VIDA VENTURES MANAGEMENT CO., LLC, By: /s/ Jean-Philippe Kouakou-Zebouah, its Managing Member  
**Date:** 2025-09-16

**Signature:** ARIE BELLDEGRUN By: /s/ Jean-Philippe Kouakou-Zebouah, his attorney-in-fact  
**Date:** 2025-09-16

**Signature:** HELEN KIM By: /s/ Jean-Philippe Kouakou-Zebouah, her attorney-in-fact  
**Date:** 2025-09-16

### Remarks:

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.**