Company: LBRX
Filing Date: 2025-09-10
Form Type: S-1MEF
Source: 0001193125-25-200422
Chunk: 0

Company: LB PHARMACEUTICALS INC
Filing Date: 2025-09-10
Form: S-1MEF
Chunk 0
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As filed with the Securities and Exchange Commission on September 10, 2025. Registration No. 333- UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 LB Pharmaceuticals Inc (Exact name of registrant as specified in its charter)

| Delaware                        |     |                         2834 |     | 81-1854347         |
| (State or other jurisdiction of 
 incorporation or organization)  |     | -Primary Standard Industrial 
   Classification Code Number |     | -I.R.S. Employer   
 Identification No. |

LB Pharmaceuticals Inc One Pennsylvania Plaza, Suite 1025 New York, NY 10119 Tel: (212) 605-0300 (Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices) Heather Turner Chief Executive Officer One Pennsylvania Plaza, Suite 1025 New York, NY 10119 Tel: (212) 605-0300 (Name, address, including zip code, and telephone number, including area code, of agent for service) Copies to:

| Divakar Gupta            
 Brandon Fenn Marc        
 Recht Minkyu Park        
 Cooley LLP 55 Hudson     
 Yards New York, NY 10001 
 Tel: (212) 479-6000      |     | William C. Hicks                                    
 John T. Rudy Alok A.                                
 Choksi Samantha M. Silver                           
 Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. 
 One Financial Center                                
 Boston, MA 02111 Tel: (617) 542-6000                |

Approximate date of commencement of proposed sale to the public:As soon as practicable after this Registration Statement becomes effective. If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box: ☐ If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☒ (333-289812) If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier