UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K/A

(Amendment No. 1)

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported): March 13, 2024

Registrant’s telephone number, including area code: (561) 589-7020

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Explanatory Note

On March 14, 2024, First Wave BioPharma, Inc. (the “Company”) filed a Current Report on Form 8-K (the “Original Form 8-K”) with the Securities and Exchange Commission in connection with the Company’s merger with ImmunogenX, Inc. (“IMGX”). This Amendment No.1 on Form 8-K/A amends the Original Form 8-K to file (i) the financial statements of IMGX required by Item 9.01(a) of Form 8-K (the “IMGX Financial Statements”), (ii) the pro forma financial information required by Item 9.01(b) of Form 8-K (together with the IMGX Financial Statements, the “IMGX Financial Information”), and (iii) a consent from Holthouse Carlin & Van Trigt LLP (“HCVT”) to incorporate by reference HCVT’s audit report included in the IMGX Financial Information into certain of the Company’s registration statements. The IMGX Financial Information and the consent of HCVT were not included in the Original Form 8-K in reliance on the instructions to such item. Except as described above, all other information in the Original Form 8-K remains unchanged.

(a) Financial statements of business acquired

Information responsive to Item 9.01(a) of Form 8-K is set forth in the financial statements filed as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

(b) Pro forma financial information

Information responsive to Item 9.01(b) of Form 8-K is filed as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated herein by reference.

(d) Exhibits

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.