Company: LBRX
Filing Date: 2025-07-23
Form Type: DRS/A
Source: 0000950123-25-006557
Chunk: 326

Company: LB PHARMACEUTICALS INC
Filing Date: 2025-07-23
Form: DRS/A
Chunk 326
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 $              |     | $           |
| Proceeds, before expenses, to us       |     | $     |     | $              |     | $           |

We estimate expenses payable by us in connection with this offering, other than the underwriting discounts and commissions referred to above, will be approximately $ . We also have agreed to reimburse the underwriters for up to $ for their FINRA counsel fee. In accordance with FINRA Rule 5110, this reimbursed fee is deemed underwriting compensation for this offering. 224

Over-Allotment Option We have granted an option to the underwriters, exercisable for 30 days after the date of this prospectus, to purchase up to additional shares at the initial public offering price, less underwriting discounts and commissions. If the underwriters exercise this option, each underwriter will be obligated, subject to the conditions contained in the underwriting agreement, to purchase a number of additional shares proportionate to that underwriter’s initial amount reflected in the above table. No Sales of Similar Securities We, our executive officers and directors and substantially all of our other existing security holders have agreed not to sell or transfer any common stock or securities convertible into or exchangeable or exercisable for common stock, for 180 days after the date of this prospectus without first obtaining the written consent of Leerink Partners LLC, Piper Sandler & Co., and Stifel, Nicolaus & Company, Incorporated on behalf of the underwriters. Specifically, we and these other persons have agreed, with certain limited exceptions, not to directly or indirectly:

| • |     | offer, pledge, sell or contract to sell any common stock; |

| • |     | sell any option or contract to purchase any common stock; |

| • |     | purchase any option or contract to sell any common stock; |

| • |     | grant any option, right or warrant for the sale of any common stock; |

| • |     | otherwise dispose of or transfer any common stock; |

| • |     | request or demand that we file a registration statement related to the common stock; or |

| • |     | enter into any swap or other agreement or any transaction that transfers, in whole or in part, the economic                                                                     
 consequence of ownership of any common stock, whether any such swap, agreement or transaction is to be settled by delivery of shares or other securities, in cash or otherwise. |

The lock-upprovisions apply to common stock and to securities convertible into or exchangeable or exerc