Company: SCLXW
Filing Date: 2025-07-23
Form Type: 424B3
Source: 0001193125-25-163077
Chunk: 251

Company: Scilex Holding Co
Filing Date: 2025-07-23
Form: 424B3
Chunk 251
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 Capital Acquisition Corp., Denali Merger Sub Inc. and Semnur Pharmaceuticals, Inc. |
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| 104     |     | Cover Page Interactive Data File, formatted in Inline Extensible Business Reporting Language (iXBRL).                                                                              |

4

SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

| SCILEX HOLDING COMPANY |     |                                     |
| By:                    |     | /s/ Jaisim Shah                     |
| Name:                  |     | Jaisim Shah                         |
| Title:                 |     | Chief Executive Officer & President |

Date: July 23, 2025 5

Exhibit 2.1

AMENDMENT NO. 2 TO AGREEMENT AND PLAN OF MERGER

THIS AMENDMENT NO. 2 TO AGREEMENT AND PLAN OF MERGER (this “”), dated as of July 22, 2025, is made
and entered into by and among Denali Capital Acquisition Corp., a Cayman Islands exempted company (which shall migrate to and domesticate as a Delaware corporation prior to the Closing, “”), Denali Merger Sub Inc., a Delaware
corporation and wholly owned subsidiary of Parent (the “” and together with Parent, collectively, the “”), and Semnur Pharmaceuticals, Inc., a Delaware corporation (the
“”).

WHEREAS, the Parent Parties and the Company have entered into an Agreement and Plan of
Merger, dated as of August 30, 2024 (as amended, restated, supplemented or otherwise modified from time to time, including pursuant to that certain Amendment No.1, dated as of April 16, 2025, the “”),
providing for, among other things, the merger of Merger Sub with and into the Company, with the Company continuing as the Surviving Corporation;

WHEREAS, prior to the completion of the transactions contemplated by the Merger Agreement, (i) Parent and the Company may
enter into one or more securities purchase agreements or similar agreements with certain investors to be named therein (the “”), pursuant to which, among other things, the Semnur Investors may purchase Company
Common Shares in an amount and at a purchase price, in each case, to be determined (including shares that may be issued into an escrow