FWBI / First Wave BioPharma, Inc. - Pengajuan SECLaporan Tahunan, Pernyataan Proksi

As filed with the Securities and Exchange Commission on August 26, 2025

As filed with the Securities and Exchange Commission on August 26, 2025 Registration Statement No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) ☐ Definitive

Security Type

Calculation of Filing Fee Tables S-1 Entero Therapeutics, Inc. Table 1: Newly Registered and Carry Forward Securities ☐Not Applicable Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum Aggregate Offering Price Fee Rate Amount of Registration Fee Carry Forward Form Type Carry Forward File Number Carry Forward I

CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF ENTERO THERAPEUTICS, INC. CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION ENTERO THERAPEUTICS, INC.

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF ENTERO THERAPEUTICS, INC. CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF ENTERO THERAPEUTICS, INC. Entero Therapeutics, Inc. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware, does

Entero Therapeutics, Inc. Announces Reverse Stock Split

Exhibit 99.1 Entero Therapeutics, Inc. Announces Reverse Stock Split BOCA RATON, FL, August 14, 2025 – Entero Therapeutics, Inc. (the “Company”) (NASDAQ: ENTO), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, announced that, it will effect a 1 for 3 reverse stock split of its common stock. The Compan

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 14, 2025

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 14, 2025 Entero Therapeutics, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2025 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001-3785

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 9, 2025

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 9, 2025 Entero Therapeutics, Inc.

Form of Pre-Funded Warrant

  Exhibit 10.2   NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE RE

Form of Registration Rights Agreement

Exhibit 10.4 REGISTRATION RIGHTS AGREEMENT This Registration Rights Agreement (this “Agreement”) is made and entered into as of August [●], 2025, between Entero Therapeutics, Inc., a Delaware corporation (the “Company”), and each of the several purchasers signatory hereto (each such purchaser, a “Purchaser” and, collectively, the “Purchasers”). This Agreement is made pursuant to the Securities Pur

Form of Securities Purchase Agreement

Exhibit 10.1 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of August 9, 2025, between Entero Therapeutics, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (including their respective successors and assigns, each, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the term

Entero Therapeutics, Inc. Announces $3.0 Million Private Placement Priced at the Market Under Nasdaq Rules

Exhibit 99.1 Entero Therapeutics, Inc. Announces $3.0 Million Private Placement Priced at the Market Under Nasdaq Rules BOCA RATON, FLA., August 11, 2025 (GLOBE NEWSWIRE) - Entero Therapeutics, Inc. (NASDAQ: ENTO) (the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, today announced that i

Form of Warrant

Exhibit 10.3 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGIST

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 15, 2025

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 15, 2025 Entero Therapeutics, Inc.

Amendment to Rescission Agreement effective July 15, 2025 by and among the Company, ImmunogenX, LLC, and the Shareholders.

Exhibit 2.1 AMENDMENT TO RESCISSION AGREEMENT This Amendment to Rescission Agreement (this “Amendment”) is made and entered into effective as of July 15, 2025, by and among Entero Therapeutics Inc., a Delaware corporation (the “Company”), ImmunogenX, LLC, a Delaware limited liability company and currently a wholly owned subsidiary of the Company (“Immuno LLC”) and each of the individuals or entiti

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 3, 2025

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 3, 2025 Entero Therapeutics, Inc.

As filed with the U.S. Securities and Exchange Commission on July 2, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1/A (Amendment No. 3) REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTIC

As filed with the U.S. Securities and Exchange Commission on July 2, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1/A (Amendment No. 3) REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter) Delaware 2834 46-4993860 (State or other jurisdiction of incorporation or organization)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 30, 2025

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 30, 2025 Entero Therapeutics, Inc.

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 25, 2025 Entero Therapeutics, Inc.

As filed with the U.S. Securities and Exchange Commission on June 23, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1/A (Amendment No. 2) REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTI

As filed with the U.S. Securities and Exchange Commission on June 23, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1/A (Amendment No. 2) REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter) Delaware 2834 46-4993860 (State or other jurisdiction of incorporation or organization

As filed with the U.S. Securities and Exchange Commission on June 5, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1/A (Amendment No. 1) REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTIC

As filed with the U.S. Securities and Exchange Commission on June 5, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1/A (Amendment No. 1) REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter) Delaware 2834 46-4993860 (State or other jurisdiction of incorporation or organization)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) ☒ Definitive

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Amendment No. 2) Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Amendment No. 2) Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Amendment No. 1) Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Amendment No. 1) Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

TABLE OF CONTENTS UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☒ Preliminary Proxy Statement ☐ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) ☐ Definitive

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2025 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001-378

Entry into a Material Definitive Agreement, Financial Statements and Exhibits, Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant, Shareholder Director Nominations

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 8, 2025 Entero Therapeutics, Inc.

Form of Marketing Agreement by and between the Company and IR Agency LLC.

Exhibit 10.27 CONSULTING AGREEMENT IR Agency LLC (the “Consultant” or “IR Agency”) is pleased to provide certain consulting services to Entero Therapeutics Inc (“you,” “Client” or “Company”) as more fully described in this agreement (the “Agreement”). This Agreement sets forth the terms and conditions pursuant to which Company engages Consultant to provide such services. 1. Consulting Services. (a

Third Amended and Restated Revolving Loan Promissory Note dated April 9, 2025.

Exhibit 10.30 THIRD AMENDED AND RESTATED REVOLVING LOAN PROMISSORY NOTE (“NOTE”) Principal Amount: $2,436,338.30 Date of Note: April 9, 2025 FOR VALUE RECEIVED, on the Revolving Loan Termination Date, the undersigned, IMMUNOGENX, LLC, a Delaware limited liability company (“Borrower”), hereby promises to pay to MATTRESS LIQUIDATORS, INC., a Colorado corporation, its successors and assigns (“Lender”

Amended and Restated Subordination Agreement dated April 9, 2025 by and among Mattress Liquidators, Inc., Felker Revocable Trust Dated July 30, 1999 and ImmunogenX, LLC.

Exhibit 10.32 AMENDED AND RESTATED SUBORDINATION AGREEMENT This Amended and Restated Subordination Agreement (this “Agreement”) is dated as of April 9, 2025 by and among MATTRESS LIQUIDATORS, INC., a Colorado corporation (together with its successors and assigns, the “Lender”), FELKER REVOCABLE TRUST DATED JULY 30, 1999, an individual (the “Subordinating Creditor”), and IMMUNOGENX, LLC, a Delaware

Amended and Restated Subordination Agreement dated April 9, 2025 by and among Mattress Liquidators, Inc., ImmunogenX, LLC and The Jack A. Syage and Elizabeth T. Syage Trust.

Exhibit 10.31 AMENDED AND RESTATED SUBORDINATION AGREEMENT This Amended and Restated Subordination Agreement (this “Agreement”) is dated as of April 9, 2025 by and among MATTRESS LIQUIDATORS, INC., a Colorado corporation (together with its successors and assigns, the “Lender”), THE JACK A. SYAGE AND ELIZABETH C. SYAGE REVOCABLE TRUST DATED NOVEMBER 30, 1999 (the “Subordinating Creditor”), and IMMU

Form of Pre-Funded Warrant.

Exhibit 4.19 PRE-FUNDED COMMON STOCK PURCHASE WARRANT ENTERO THERAPEUTICS, INC. Warrant Shares: [·] Issue Date: , 2025 Initial Exercise Date: , 2025 THIS PRE-FUNDED COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any tim

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter)

As filed with the U.S. Securities and Exchange Commission on May 12, 2025. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter) Delaware 2834 46-4993860 (State or other jurisdiction of incorporation or organization) (Primary Standard I

Form of Underwriting Agreement

Exhibit 1.1 Entero Therapeutics, Inc. UNDERWRITING AGREEMENT , 2025 WestPark Capital, Inc. 1800 Century Park East, Suite 220 Los Angeles, CA 90067 As representative of the several underwriters named in Schedule 1 hereto Ladies and Gentlemen: The undersigned, Entero Therapeutics, Inc., a company incorporated under the law of the State of Delaware (the “Company”), hereby confirms its agreement (this

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) Entero Therapeutics, Inc.

Settlement Agreement dated April 9, 2025 by and between Mattress Liquidators, Inc., ImmunogenX, LLC, Jack A. Syage and The Jack A. Syage and Elizabeth T. Syage Trust.

Exhibit 10.28 SETTLEMENT AGREEMENT THIS SETTLEMENT AGREEMENT (the “Agreement”) is entered into effective as of April 9, 2025 (the “Effective Date”), by and between Mattress Liquidators, Inc., a Colorado corporation (“Lender”), ImmunogenX, LLC, a Delaware limited liability company (“Borrower”), Jack A. Syage (“Jack”), and The Jack A. Syage and Elizabeth T. Syage (the “Trust,” collectively with Jack

Amended and Restated Credit Agreement dated April 9, 2025, by and between ImmunogenX, LLC and Mattress Liquidators, Inc.

Exhibit 10.29 AMENDED AND RESTATED CREDIT AGREEMENT Dated as of April 9, 2025 IMMUNOGENX, LLC as Borrower and MATTRESS LIQUIDATORS, INC. as Lender TABLE OF CONTENTS Section Heading Page SECTION 1. Definitions; Interpretation 1 Section 1.1. Definitions. 1 Section 1.2. Interpretation 6 SECTION 2. The Credit Facilities 7 Section 2.1. Revolving Loan 7 Section 2.2. Disbursement of Revolving Loan. 7 Sec

Form of Amendment to the Rescission Agreement by and between the Company, ImmunogenX, LLC and certain shareholders of the Company.

Exhibit 10.26 AMENDMENT TO RESCISSION AGREEMENT This Amendment to Rescission Agreement (this “Amendment”) is made and entered into effective as of , 2025, by and among Entero Therapeutics Inc., a Delaware corporation (the “Company”), ImmunogenX, LLC, a Delaware limited liability company and currently a wholly owned subsidiary of the Company (“Immuno LLC”) and each of the individuals or entities (e

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 ENTERO THERAPEUTICS, INC. (Exact name of registrant as specified in its charter)

As confidentially submitted to the U.S. Securities and Exchange Commission on April 17, 2025. This draft registration statement has not been publicly filed with the U.S Securities and Exchange Commission and all information herein remains strictly confidential. UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM S-1 REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933 E

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): April 11, 2025 Entero Therapeutics, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 10-K/A

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 10-K/A ☒ ANNUAL REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file Number 001-37853 ENTERO THERAPEUTICS, INC.

Description of Capital Stock*

Exhibit 4.20 DESCRIPTION OF CAPITAL STOCK The following is a summary of information concerning capital stock of First Wave BioPharma, Inc. (“us,” “our,” “we” or the “Company”) and certain provisions of our certificate of incorporation, as amended and restated, and amended and restated bylaws currently in effect. This summary does not purport to be complete and is qualified in its entirety by the p

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 10-K ☒ ANNUAL REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2024 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file Number 001-37853 ENTERO THERAPEUTICS, INC.

Exhibit 4.20

Exhibit 4.20 DESCRIPTION OF CAPITAL STOCK The following is a summary of information concerning capital stock of First Wave BioPharma, Inc. (“us,” “our,” “we” or the “Company”) and certain provisions of our certificate of incorporation, as amended and restated, and amended and restated bylaws currently in effect. This summary does not purport to be complete and is qualified in its entirety by the p

Read Instructions (on back page) Before Preparing Form. Please Print or Type. Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.

UNITED STATES OMB APPROVAL SECURITIES AND EXCHANGE COMMISSION OMB Number: 3235-0058 Washington, D.

Entero Therapeutics Announces Signing of Rescission Agreement with ImmunogenX, LLC.

Exhibit 99.1 Entero Therapeutics Announces Signing of Rescission Agreement with ImmunogenX, LLC. BOCA RATON, Fla., March 24, 2025 (GLOBE NEWSWIRE) – Entero Therapeutics, Inc. (Nasdaq: ENTO) (“Entero” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, announced today that Entero has su

Rescission Agreement effective March 24, 2025, by and among the Company, IMGX, currently a wholly owned subsidiary of the Company, and each of the individuals or entities who are the former shareholders of IMGX (incorporated by reference to Exhibit 2.1 of the Company's Current Report on Form 8-K filed with the SEC on March 25, 2025

Exhibit 2.1 RESCISSION AGREEMENT THIS RESCISSION AGREEMENT, dated as of March 14, 2025 is made by and among ENTERO THERAPEUTICS, INC. (formerly First Wave Biopharma, Inc.), a Delaware corporation (the “Company”), ImmunogenX, LLC, a Delaware limited liability company and currently a wholly owned subsidiary of the Company (“Immuno LLC”) and each of the individuals or entities (each a “Shareholder” a

Regulation FD Disclosure, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Entry into a Material Definitive Agreement, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 24, 2025 Entero Therapeutics, Inc.

Consulting Agreement dated March 6, 2025 with Skowron Accounting Professional Corporation (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on March 7, 2025).

Exhibit 10.1 CFO CONSULTING AGREEMENT This CFO CONSULTING AGREEMENT dated as of March 6, 2025 (this “Agreement”), is made and entered into between Entero Therapeutics, Inc. (a Delaware Corporation) (the “Company”), and Skowron Accounting Professional Corporation, an Ontario, Canada corporation (the “Consultant”). WHEREAS, the Company desires to engage the Consultant to provide certain consulting s

Form of Director Agreement (incorporated by reference to Exhibit 10.3 of the Company’s Current Report on Form 8-K filed with the SEC on March 7, 2025).

Exhibit 10.3 ENTERO THERAPEUTICS, INC. BOARD OF DIRECTORS AGREEMENT This BOARD OF DIRECTORS AGREEMENT (the “Agreement”) dated March 6, 2025 and effective as of February 12, 2025 (the “Effective Date”), by and between Entero Therapeutics, Inc. a Delaware corporation (the “Company”), and the undersigned signatory (the “Director”), provides for director services, according to the following terms and

Consulting Agreement dated March 6, 2025 with 2818390 Ontario Corp. (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8-K filed with the SEC on March 7, 2025).

Exhibit 10.2 CONSULTING AGREEMENT FOR NON-EMPLOYEE CHIEF EXECUTIVE OFFICER This CONSULTING AGREEMENT (this “Agreement”) dated March 6, 2025 and effective as of February 12, 2025 (“Effective Date”), is made and entered into between Entero Therapeutics, Inc. (a Delaware Corporation) (the “Company”), and 2818390 Ontario Corp., an Ontario, Canada corporation (the “Consultant”). WHEREAS, the Company de

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Entry into a Material Definitive Agreement, Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 3, 2025 Entero Therapeutics, Inc.

Entero Therapeutics Appoints Richard Paolone as CEO

Exhibit 99.1 Entero Therapeutics Appoints Richard Paolone as CEO BOCA RATON, Fla., Feb. 14, 2025 (GLOBE NEWSWIRE) – Entero Therapeutics, Inc. (Nasdaq: ENTO) (“Entero” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, announced today that the board of directors has appointed Mr. Richa

Regulation FD Disclosure, Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): February 12, 2025 Entero Therapeutics, Inc.

Revolving Loan Agreement (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on February 6, 2025).

Exhibit 10.1 REVOLVING LOAN AGREEMENT This Revolving Loan Agreement (this “Agreement”) is dated as of January 27, 2025 between Entero Therapeutics, Inc., a Delaware corporation (the “Borrower”), and the purchaser identified on the signature page hereto (including its successors and assigns, the “Lender”). WHEREAS, Borrower wishes to obtain Loans from time to time from Lender in an aggregate princi

Revolving Note (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8-K filed with the SEC on February 6, 2025).

Exhibit 10.2 REVOLVING NOTE January 27, 2025 Up to $2,000,000 FOR VALUE RECEIVED, Entero Therapeutics, Inc., a Delaware corporation (“Borrower”) HEREBY PROMISES TO PAY to the order of 1396974 BC Ltd. (together with its successors, participants and assigns, “Lender”), in lawful money of the United States of America and in immediately available funds, the principal amount of TWO MILLION DOLLARS ($2,

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 31, 2025

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 31, 2025 Entero Therapeutics, Inc.

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 7, 2025 Entero Therapeutics, Inc.

Triggering Events That Accelerate or Increase a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 21, 2024 Entero Therapeutics, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2024 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001

Entero Therapeutics Announces Proposed Reverse Merger with Journey Therapeutics, A Clinical Stage, First-in-Class, Next-Generation ADC-rivalling Nano-immunoconjugates Biopharmaceutical Company

Exhibit 99.1 Entero Therapeutics Announces Proposed Reverse Merger with Journey Therapeutics, A Clinical Stage, First-in-Class, Next-Generation ADC-rivalling Nano-immunoconjugates Biopharmaceutical Company · Proposed merger to create Nasdaq-listed, clinical-stage biopharmaceutical company focused on advancing (i) Journey’s next-gen, first-in-class ADC-rivalling, nano-immunoconjugates (“NIC”) platf

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 8, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): November 8, 2024 Entero Therapeutics, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2024 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001-3785

Amended and Restated Certificate of Incorporation of the Registrant, as amended (incorporated by reference to Exhibit 3.1 to the Company’s Quarterly Report on Form 10-Q filed with the SEC on October 21, 2024).

Exhibit 3.1 Delaware Page 1 The First State I, JEFFREY W. BULLOCK, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED ARE TRUE AND CORRECT COPIES OF ALL DOCUMENTS FILED FROM AND INCLUDING THE RESTATED CERTIFICATE OR A MERGER WITH A RESTATED CERTIFICATE ATTACHED OF “ENTERO THERAPEUTICS, INC.” AS RECEIVED AND FILED IN THIS OFFICE. THE FOLLOWING DOCUMENTS HAVE BEEN CERTIFIED:

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 6, 2024 Entero Therapeutics, Inc.

Entero Therapeutics Signs Letter of Intent to License and Commercialize Remote Patient and Machine Vision Clinical Trial Management Platform from Data Vault Holdings Entero Therapeutics to integrate applications in planned Phase 3 study of latigluten

Exhibit 99.1 Entero Therapeutics Signs Letter of Intent to License and Commercialize Remote Patient and Machine Vision Clinical Trial Management Platform from Data Vault Holdings Entero Therapeutics to integrate applications in planned Phase 3 study of latiglutenase for celiac disease and explore additional uses of technology in clinical trial compliance BOCA RATON, Fla., September 10, 2024 (GLOBE

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 9, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 9, 2024 Entero Therapeutics, Inc.

Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 29, 2024 Entero Therapeutics, Inc.

Letter from Macias Gini & O’Connell LLP to the U.S. Securities and Exchange Commission, dated August 29, 2024 (incorporated by reference to Exhibit 16.1 of the Company’s Current Report on Form 8-K filed with the SEC on August 29, 2024).

Exhibit 16.1 August 29, 2024 Securities and Exchange Commission 100 F Street, NE Washington, DC 20549 Dear Ladies and Gentlemen: We have read the statements made by Entero Therapeutics, Inc. (the “Company”) (copy attached), which we understand will be filed with the Securities and Exchange Commission pursuant to Item 4.01 of Form 8-K, as part of the Form 8-K dated August 29, 2024. We agree with th

Financial Statements and Exhibits, Changes in Registrant's Certifying Accountant

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 28, 2024 Entero Therapeutics, Inc.

Entero Therapeutics, Inc. Receives Nasdaq Notification Regarding Delayed Form 10-Q

Exhibit 99.1 Entero Therapeutics, Inc. Receives Nasdaq Notification Regarding Delayed Form 10-Q BOCA RATON, Fla., August 23, 2024 (GLOBE NEWSWIRE) – Entero Therapeutics, Inc., (NASDAQ: ENTO), (“Entero Therapeutics” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, today announced tha

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 21, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 21, 2024 Entero Therapeutics, Inc.

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 16, 2024 Entero Therapeutics, Inc.

Letter from Forvis Mazars, LLP to the U.S. Securities and Exchange Commission, dated August 15, 2024 (incorporated by reference to Exhibit 16.1 of the Company’s Current Report on Form 8-K filed with the SEC on August 15, 2024).

Exhibit 16.1 August 15, 2024 U.S. Securities and Exchange Commission 100 F Street, NE Washington, DC 20549 Ladies and Gentlemen: We have read Item 4.01 of Form 8-K dated August 15, 2024 of Entero Therapeutics, Inc. and are in agreement with the statements therein concerning Forvis Mazars, LLP. We have no basis to agree or disagree with other statements of the registrant contained therein. /s/ Forv

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 9, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 9, 2024 Entero Therapeutics, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 12b-25 NOTIFICATION OF LATE FILING (Check one): ¨ Form 10-K ¨ Form 20-F ¨ Form 11-K x Form 10-Q ¨ Form 10-D ¨ Form N-SAR ¨ Form N-CSR For Period Ended: June 30, 2024 ¨ Transition Report on Form 10-K ¨ Transition Report on Form 20-F ¨ Transition Report on Form 11-K ¨ Transition Report on Form 10-Q ¨ Transition Report on Fo

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 1, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 1, 2024 Entero Therapeutics, Inc.

Consulting Agreement, dated August 2, 2024, by and between the Company and James Sapirstein.

Exhibit 10.1 CONSULTING AGREEMENT This consulting agreement (the “Agreement”) is effective as of August 2, 2024 (the “Effective Date”) by and between Entero Therapeutics, Inc., a Delaware corporation with its principal place of business located at 777 Yamato Road, Suite 502, Boca Raton, FL 33431 (the “Company”) and James Sapirstein with an address at 5310 Boca Marina Circle N, Boca Raton, FL 33487

Entero Therapeutics’ Chairman and CEO James Sapirstein Provides Business Update with Focus on Latiglutenase Development Program

Exhibit 99.1 Entero Therapeutics’ Chairman and CEO James Sapirstein Provides Business Update with Focus on Latiglutenase Development Program BOCA RATON, Fla., July 31, 2024 (GLOBE NEWSWIRE) – Entero Therapeutics, Inc., (NASDAQ: ENTO), (“Entero Therapeutics” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastroin

Regulation FD Disclosure, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 31, 2024 Entero Therapeutics, Inc.

As filed with the Securities and Exchange Commission on July 26, 2024

As filed with the Securities and Exchange Commission on July 26, 2024 Registration No.

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-3 (Form Type) Entero Therapeutics, Inc.

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 17, 2024 Entero Therapeutics, Inc.

Entero Therapeutics Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $1.9 Million Gross Proceeds

Exhibit 99.1 Entero Therapeutics Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $1.9 Million Gross Proceeds BOCA RATON, Fla., July 11, 2024 (GLOBE NEWSWIRE) – Entero Therapeutics, Inc. (“Entero” or the “Company”) (NASDAQ: ENTO), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 10, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 10, 2024 Entero Therapeutics, Inc.

Form of Inducement Warrant (incorporated by reference to Exhibit 4.1 of the Company’s Annual Report on Form 10-K filed with the SEC on July 11, 2024).

Exhibit 4.1 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTR

Form of Inducement Letter (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on July 11, 2024).

Exhibit 10.1 July 10, 2024 Armistice Capital Master Fund Ltd. c/o Armistice Capital, LLC 510 Madison Avenue, 7th Floor New York, NY 10022 Re: Reprice and Reload Offer of Common Stock Purchase Warrants To Whom It May Concern: Entero Therapeutics, Inc. (the “Company”) is pleased to offer to you the opportunity to receive new Common Stock purchase warrants of the Company in consideration for the exer

Calculation of Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-8 (Form Type) Entero Therapeutics, Inc.

As filed with the Securities and Exchange Commission on June 24, 2024

As filed with the Securities and Exchange Commission on June 24, 2024 Registration No.

Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 17, 2024 Entero Therapeutics, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Amendment No. 1) Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A (Amendment No. 1) Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: x Preliminary Proxy Statement ¨ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive

1,257,625 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-279896 PROSPECTUS 1,257,625 Shares of Common Stock This prospectus relates to the offer and resale of up to an aggregate of 1,257,625 shares of common stock, par value $0.0001 per share (the “Common Stock”) of Entero Therapeutics, Inc., formerly known as First Wave BioPharma, Inc. (the “Company,” “we,” “our” or “us”), held by the selling stockh

Entero Therapeutics, Inc. 777 Yamato Road, Suite 502 Boca Raton, Florida 33431 June 7, 2024

Entero Therapeutics, Inc. 777 Yamato Road, Suite 502 Boca Raton, Florida 33431 June 7, 2024 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Life Sciences 100 F Street, N.E. Washington, D.C. 20549 Attention: Jason Drory Re: Entero Therapeutics, Inc. (the “Company”) Registration Statement on Form S-3 Filed on May 31, 2024 File No. 333-279896 Dear

Letter from Mazars USA LLP to the U.S. Securities and Exchange Commission, dated June 5, 2024 (incorporated by reference to Exhibit 16.1 of the Company’s Current Report on Form 8-K filed with the SEC on June 5, 2024).

Exhibit 16.1 June 5, 2024 U.S. Securities and Exchange Commission 100 F Street, NE Washington, DC 20549 Ladies and Gentlemen: We have read Item 4.01 of Form 8-K dated June 5, 2024 of Entero Threapeutics, Inc. and are in agreement with the statements therein concerning Mazars USA LLP. We have no basis to agree or disagree with other statements of the registrant contained therein. /s/ Mazars USA LLP

Financial Statements and Exhibits, Changes in Registrant's Certifying Accountant

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 1, 2024 Entero Therapeutics, Inc.

As filed with the Securities and Exchange Commission on May 31, 2024

As filed with the Securities and Exchange Commission on May 31, 2024 Registration No.

Filing Fee Table

Exhibit 107 Calculation of Filing Fee Tables S-3 (Form Type) First Wave BioPharma, Inc.

Unaudited pro forma combined statements of operations of the Company and IMGX for the three months ended March 31, 2024.

Exhibit 99.3 Unaudited Pro Forma Condensed Combined Statement of Operations The following unaudited pro forma combined financial information has been prepared in accordance with Article 11 of Regulation S-X under the Securities Act of 1933, as amended (the “Securities Act”) and presents the combined historical results of operations of Entero Therapeutics, Inc. (formerly known as First Wave BioPhar

Unaudited Pro Forma Condensed Combined Statement of Operations

Exhibit 99.3 Unaudited Pro Forma Condensed Combined Statement of Operations The following unaudited pro forma combined financial information has been prepared in accordance with Article 11 of Regulation S-X under the Securities Act of 1933, as amended (the “Securities Act”) and presents the combined historical results of operations of Entero Therapeutics, Inc. (formerly known as First Wave BioPhar

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K/A (Amendment No. 2) 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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K/A (Amendment No.

Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K/A (Amendment No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 15, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 15, 2024 Entero Therapeutics, Inc.

First Wave BioPharma Changes Name to Entero Therapeutics Rebranding introduced as Company advances toward Phase 3 clinical trial with lead asset – latiglutenase for the treatment of celiac disease New Nasdaq new ticker symbol is “ENTO” effective May

Exhibit 99.1 First Wave BioPharma Changes Name to Entero Therapeutics Rebranding introduced as Company advances toward Phase 3 clinical trial with lead asset – latiglutenase for the treatment of celiac disease New Nasdaq new ticker symbol is “ENTO” effective May 17, 2024 BOCA RATON, Fla., May 16, 2024 (GLOBE NEWSWIRE) – Entero Therapeutics, Inc. (formerly First Wave BioPharma, Inc.) (Nasdaq: ENTO)

Certificate of Amendment to the Amended and Restated Certificate of Incorporation, as amended, of First Wave BioPharma, Inc. dated May 15, 2024 (incorporated by reference to Exhibit 3.1 of the Company’s Current Report on Form 8-K filed with the SEC on May 15, 2024).

Exhibit 3.1 Delaware The First State Page 1 5474088 8100 Authentication: 203479364 SR# 20242146035 Date: 05-15-24 You may verify this certificate online at corp.delaware.gov/authver.shtml I, JEFFREY W. BULLOCK, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED IS A TRUE AND CORRECT COPY OF THE CERTIFICATE OF AMENDMENT OF “FIRST WAVE BIOPHARMA, INC.”, CHANGING ITS NAME FRO

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2024 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001-378

Form of Purchase Agreement (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8 - K filed with the SEC on May13, 2024).

Exhibit 10.2 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of May 10, 2024, between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the terms and conditio

Form of Common Warrant (incorporated by reference to Exhibit 4.2 of the Company’s Current Report on Form 8-K filed with the SEC on May 13, 2024).

Exhibit 4.2 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTR

Form of Placement Agency Agreement (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on May 13, 2024).

Exhibit 10.1 PLACEMENT AGENCY AGREEMENT May 10, 2024 Roth Capital Partners, LLC 888 San Clemente Drive, Suite 400 Newport Beach, CA 92660 Ladies and Gentlemen: Introduction. Subject to the terms and conditions herein (this “Agreement”), First Wave BioPharma, Inc., a Delaware corporation (the “Company”), hereby agrees to sell up to an aggregate of $1,079,700 of registered securities of the Company,

First Wave BioPharma, Inc. to raise approximately $1.1 million of Gross Proceeds Priced At-the-Market

Exhibit 99.1 First Wave BioPharma, Inc. to raise approximately $1.1 million of Gross Proceeds Priced At-the-Market BOCA RATON, Fla., May 10, 2024 – First Wave BioPharma, Inc., (NASDAQ: FWBI), (“First Wave BioPharma” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, announced today th

275,000 Shares of Common Stock 91,000 Prefunded Warrants to Purchase up to 91,000 Shares of Common Stock 91,000 Shares of Common Stock underlying the Prefunded Warrants

Filed Pursuant to Rule 424(b)(5) Registration No. 333-256476 PROSPECTUS SUPPLEMENT (To Prospectus Dated June 2, 2021) 275,000 Shares of Common Stock 91,000 Prefunded Warrants to Purchase up to 91,000 Shares of Common Stock 91,000 Shares of Common Stock underlying the Prefunded Warrants We are offering 275,000 shares of our common stock, and prefunded warrants (the “Prefunded Warrants”) to purchase

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Unregistered Sales of Equity Securities, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): May 10, 2024 First Wave BioPharma, Inc.

Form of Pre - Funded Warrant (incorporated by reference to Exhibit 4.1 of the Company’s Current Report on Form 8 - K filed with the SEC on May 13, 2024).

Exhibit 4.1 PRE-FUNDED COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: May 14, 2024 THIS PRE-FUNDED COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: x Preliminary Proxy Statement ¨ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy Statement ¨

Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K/A (Amendment No.

ImmunogenX, Inc. FINANCIAL STATEMENTS INDEPENDENT AUDITOR’S REPORT December 31, 2023, 2022 AND 2021

Exhibit 99.1 ImmunogenX, Inc. FINANCIAL STATEMENTS AND INDEPENDENT AUDITOR’S REPORT December 31, 2023, 2022 AND 2021 ImmunogenX, Inc. TABLE OF CONTENTS December 31, 2023, 2022 AND 2021 Page No. Independent Auditor’s Report 1 – 2 Financial Statements: Balance Sheets 3 Statements of Operations 4 Statements of Changes in Stockholders’ Deficit 5 Statements of Cash Flows 6 Notes to Financial Statements

UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION

Exhibit 99.2 UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION The following unaudited pro forma combined financial information has been prepared in accordance with Article 11 of Regulation S-X under the Securities Act of 1933, as amended (the “Securities Act”) and presents the combined historical financial position and results of operations of First Wave BioPharma, Inc. (“First Wave” or the “Com

Exhibit 19.1

Exhibit 19.1 FIRST WAVE BIOPHARMA, INC. REVISED INSIDER TRADING POLICY ADOPTED SEPTEMBER 20, 2023 I. Persons Covered. This Insider Trading Policy (the “Policy”) provides guidelines to employees, officers and directors of First Wave BioPharma, Inc. and its subsidiaries (the “Company”) with respect to trading in the Company's securities. In certain instances, this Policy also applies to consultants

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 10-K

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 FORM 10-K ☒ ANNUAL REPORT UNDER SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2023 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file Number 001-37853 FIRST WAVE BIOPHARMA, INC.

Subsidiaries of the Registrant (incorporated by reference to Exhibit 21.1 of the Company’s Annual Report on Form 10-K filed with the SEC on April 1, 2025).

Exhibit 21.1 Subsidiaries of the Registrant First Wave Bio, Inc., a Delaware corporation ImmunogenX, LLC

Exhibit 4.31

Exhibit 4.31 DESCRIPTION OF CAPITAL STOCK The following is a summary of information concerning capital stock of First Wave BioPharma, Inc. (“us,” “our,” “we” or the “Company”) and certain provisions of our certificate of incorporation, as amended and restated, and amended and restated bylaws currently in effect. This summary does not purport to be complete and is qualified in its entirety by the p

Form of Purchase Agreement.

Exhibit 10.53 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of March 3, 2024, between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the terms and condit

Compensation Recovery Policy (incorporated by reference to Exhibit 97.1 of the Company’s Annual Report on Form 10-K filed with the SEC on March 29, 2024).

Exhibit 97.1 FIRST WAVE BIOPHARMA, INC. COMPENSATION RECOVERY POLICY As adopted on September 20, 2023 First Wave Biopharma, Inc. (the “Company”) is committed to strong corporate governance. As part of this commitment, the Company’s Board of Directors (the “Board”) has adopted this clawback policy called the Compensation Recovery Policy (the “Policy”). The Policy is intended to further the Company’

Code of Business Conduct and Ethics (incorporated by reference to Exhibit 97.1 of the Company’s Annual Report on Form 10-K filed with the SEC on March 29, 2024).

Exhibit 14.1 CODE OF ETHICS OF FIRST WAVE BIOPHARMA, INC. APPLICABLE TO DIRECTORS, OFFICERS, AND EMPLOYEES To promote the ethical conduct and integrity generally of First Wave BioPharma, Inc. (the “Company”), and to promote accurate, fair and timely reporting of the Company's financial results and condition and other information the Company releases to the public market and include in reports it f

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 19, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 19, 2024 First Wave BioPharma, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 18, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 18, 2024 First Wave BioPharma, Inc.

First Wave BioPharma Announces Two Abstracts on Celiac Disease Research Accepted for Presentation at the 2024 Digestive Disease Week (DDW) Conference Poster presentations to highlight new quantitative and serologic diagnostic methods for Celiac Disea

Exhibit 99.1 First Wave BioPharma Announces Two Abstracts on Celiac Disease Research Accepted for Presentation at the 2024 Digestive Disease Week (DDW) Conference Poster presentations to highlight new quantitative and serologic diagnostic methods for Celiac Disease detection and determination of intestinal mucosal health New tools may serve as companion diagnostics for identifying seroactive patie

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) ¨ Definitive Proxy State

Form of Shareholder Note (incorporated by reference to Exhibit 10.5 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 10.5 FORM OF SECURED PROMISSORY NOTE , 2024 $ For value received, IMMUNOGENX, INC, a Delaware corporation ( “Maker”), hereby promises to pay to the order of (the “Holder”) or to the Holder’s registered assigns, the sum of ($) and any unpaid accrued interest hereon, as set forth below. Payment of principal and unpaid accrued interest under this Secured Promissory Note (as amended, restated,

Certificate of Designation of Series G Non-Voting Convertible Preferred Stock (incorporated by reference to Exhibit 3.1 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 3.1 FIRST WAVE BIOPHARMA, INC. CERTIFICATE OF DESIGNATION OF PREFERENCES, RIGHTS AND LIMITATIONS OF SERIES G NON-VOTING CONVERTIBLE PREFERRED STOCK Pursuant to Section 151 of the General Corporation Law of the State of Delaware THE UNDERSIGNED DOES HEREBY CERTIFY, on behalf of First Wave BioPharma, Inc., a Delaware corporation (the “Corporation”), that the following resolution was duly ado

Certificate of Designation of Series G Non-Voting Convertible Preferred Stock

Exhibit 3.1 FIRST WAVE BIOPHARMA, INC. CERTIFICATE OF DESIGNATION OF PREFERENCES, RIGHTS AND LIMITATIONS OF SERIES G NON-VOTING CONVERTIBLE PREFERRED STOCK Pursuant to Section 151 of the General Corporation Law of the State of Delaware THE UNDERSIGNED DOES HEREBY CERTIFY, on behalf of First Wave BioPharma, Inc., a Delaware corporation (the “Corporation”), that the following resolution was duly ado

Form of Assumed Warrant (incorporated by reference to Exhibit 4.1 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 4.1 FORM OF WARRANT THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE SECURITIES UNDER SUCH ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED. No. WARRANT TO PURCHASE COMMON STOCK of IMMUNOG

First Wave BioPharma Announces Completion of Business Combination with ImmunogenX, Adding Phase 3-Ready Latiglutenase to its Late-Stage GI-Focused Clinical Pipeline Latiglutenase is a potentially first-in-class oral biotherapeutic for the treatment o

Exhibit 99.1 First Wave BioPharma Announces Completion of Business Combination with ImmunogenX, Adding Phase 3-Ready Latiglutenase to its Late-Stage GI-Focused Clinical Pipeline Latiglutenase is a potentially first-in-class oral biotherapeutic for the treatment of celiac disease James Sapirstein, Chairman and Chief Executive Officer, to continue leading First Wave BioPharma; Jack Syage, Ph.D., nam

Offer Letter, dated as of March 13, 2024, by and between Dr. Syage and the Company

Exhibit 10.7 Jack Syage March 13, 2024 Dear Jack, First Wave BioPharma, Inc. is pleased to offer you the position of President and Chief Operating Officer, contingent on completion of a background check and I-9 verification. You will report to James Sapirstein, CEO of First Wave BioPharma, Inc. Your first day of employment with us is March 14, 2024. The terms of the offer are as follows: · A semi-

Agreement and Plan of Merger dated March 13, 2024, by and among First Wave BioPharma, Inc., IMMUNO Merger Sub II, LLC, and ImmunogenX Inc. (incorporated by reference to Exhibit 2.1 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).##

Exhibit 2.1 Execution Version AGREEMENT AND PLAN OF MERGER among: FIRST WAVE BIOPHARMA, INC.; IMMUNO MERGER SUB I, INC.; IMMUNO MERGER SUB II, LLC; and IMMUNOGENX, INC. Dated as of March 13, 2024 TABLE OF CONTENTS Page Section 1. Definitions and Interpretative Provisions 3 1.1 Definitions 3 1.2 Other Definitional and Interpretative Provisions 14 Section 2. Description of Transaction 15 2.1 The Mer

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 First Wave BioPharma, Inc.

Security Agreement, dated as of October 3, 2022, by and between ImmunogenX and Mattress Liquidators, Inc. (incorporated by reference to Exhibit 10.3 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 10.3 SECURITY AGREEMENT THIS SECURITY AGREEMENT (this “Security Agreement”) is entered into as October 3, 2022, by and between IMMUNOGENX, INC., a Delaware corporation (“Borrower”), and MATTRESS LIQUIDATORS, INC., a Colorado corporation, its successors and assigns (“Lender”). RECITALS A.          WHEREAS, pursuant to that certain Credit Agreement (as may be amended, supplemented, amended a

Second Amended and Restated Revolving Loan Promissory Note, dated March 13, 2024

Exhibit 10.2 SECOND AMENDED and restated REVOLVING Loan PROMISSORY NOTE (“Note”) Principal Amount: $8,212,345.17 Date of Note: March 13, 2024 FOR VALUE RECEIVED, on the Revolving Loan Termination Date, the undersigned, IMMUNOGENX, INC., a Delaware corporation (“Borrower”), hereby promises to pay to MATTRESS LIQUIDATORS, INC., a Colorado corporation, its successors and assigns (“Lender”) in accorda

Offer Letter, dated as of March 13, 2024, by and between Dr. Syage and the Company

Exhibit 10.7 Jack Syage March 13, 2024 Dear Jack, First Wave BioPharma, Inc. is pleased to offer you the position of President and Chief Operating Officer, contingent on completion of a background check and I-9 verification. You will report to James Sapirstein, CEO of First Wave BioPharma, Inc. Your first day of employment with us is March 14, 2024. The terms of the offer are as follows: · A semi-

Lender Support Letter, dated as of March 13, 2024, by and between ImmunogenX and Mattress Liquidators, Inc.

Exhibit 10.4 Lender Support Letter March 13, 2024 ImmunogenX, Inc. 1600 Dove Street, Suite 330 Newport Beach, CA 92660 Attention: Jack A. Syage Chief Executive Officer Ladies and Gentlemen: Reference is made to the Credit Agreement, dated as of October 1, 2022 (as amended, restated, supplemented or otherwise modified from time to time, the “Credit Agreement”), by and between ImmunogenX, Inc., a De

Form of Assumed Warrant

Exhibit 4.1 FORM OF WARRANT THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE SECURITIES UNDER SUCH ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED. No. WARRANT TO PURCHASE COMMON STOCK of IMMUNOG

Form of Shareholder Security Agreement (incorporated by reference to Exhibit 10.6 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 10.6 FORM OF PATENT AND TRADEMARK SECURITY AGREEMENT This Patent and Trademark Security Agreement (as amended, restated, supplemented or otherwise modified from time to time, this “Agreement”), dated as of , 2024, is made by and between IMMUNOGENX, INC., a Delaware corporation, having a business address of 1600 Dove Street, Suite 330, Newport Beach, CA 92660 (together with its affiliates,

Security Agreement, dated as of October 3, 2022, by and between ImmunogenX and Mattress Liquidators, Inc.

Exhibit 10.3 SECURITY AGREEMENT THIS SECURITY AGREEMENT (this “Security Agreement”) is entered into as October 3, 2022, by and between IMMUNOGENX, INC., a Delaware corporation (“Borrower”), and MATTRESS LIQUIDATORS, INC., a Colorado corporation, its successors and assigns (“Lender”). RECITALS A.          WHEREAS, pursuant to that certain Credit Agreement (as may be amended, supplemented, amended a

Second Amended and Restated Revolving Loan Promissory Note, dated March 13, 2024 (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 10.2 SECOND AMENDED and restated REVOLVING Loan PROMISSORY NOTE (“Note”) Principal Amount: $8,212,345.17 Date of Note: March 13, 2024 FOR VALUE RECEIVED, on the Revolving Loan Termination Date, the undersigned, IMMUNOGENX, INC., a Delaware corporation (“Borrower”), hereby promises to pay to MATTRESS LIQUIDATORS, INC., a Colorado corporation, its successors and assigns (“Lender”) in accorda

Press release of First Wave BioPharma, Inc.

Exhibit 99.1 First Wave BioPharma Announces Completion of Business Combination with ImmunogenX, Adding Phase 3-Ready Latiglutenase to its Late-Stage GI-Focused Clinical Pipeline Latiglutenase is a potentially first-in-class oral biotherapeutic for the treatment of celiac disease James Sapirstein, Chairman and Chief Executive Officer, to continue leading First Wave BioPharma; Jack Syage, Ph.D., nam

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 First Wave BioPharma, Inc.

Form of Shareholder Security Agreement

Exhibit 10.6 FORM OF PATENT AND TRADEMARK SECURITY AGREEMENT This Patent and Trademark Security Agreement (as amended, restated, supplemented or otherwise modified from time to time, this “Agreement”), dated as of , 2024, is made by and between IMMUNOGENX, INC., a Delaware corporation, having a business address of 1600 Dove Street, Suite 330, Newport Beach, CA 92660 (together with its affiliates,

Form of Shareholder Note

Exhibit 10.5 FORM OF SECURED PROMISSORY NOTE , 2024 $ For value received, IMMUNOGENX, INC, a Delaware corporation ( “Maker”), hereby promises to pay to the order of (the “Holder”) or to the Holder’s registered assigns, the sum of ($) and any unpaid accrued interest hereon, as set forth below. Payment of principal and unpaid accrued interest under this Secured Promissory Note (as amended, restated,

Lender Support Letter, dated as of March 13, 2024, by and between ImmunogenX and Mattress Liquidators, Inc. (incorporated by reference to Exhibit 10.4 of the Company’s Current Report on Form 8-K filed with the SEC on March 13, 2024).

Exhibit 10.4 Lender Support Letter March 13, 2024 ImmunogenX, Inc. 1600 Dove Street, Suite 330 Newport Beach, CA 92660 Attention: Jack A. Syage Chief Executive Officer Ladies and Gentlemen: Reference is made to the Credit Agreement, dated as of October 1, 2022 (as amended, restated, supplemented or otherwise modified from time to time, the “Credit Agreement”), by and between ImmunogenX, Inc., a De

Amended Credit Agreement, dated as of October 3, 2022 and amended on September 6, 2023 and March 13, 2024, by and between the Company and Mattress Liquidators, Inc. (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8 - K filed with the SEC on March 13, 2024).

  Exhibit 10.1       CREDIT AGREEMENT   Dated as of October 3, 2022   IMMUNOGENX, INC. as Borrower   and   MATTRESS LIQUIDATORS, INC. as Lender             TABLE OF CONTENTS    Section Heading Page       SECTION 1. Definitions; Interpretation 1       Section 1.1. Definitions 1 Section 1.2. Interpretation 6       SECTION 2. The Credit Facilities 6       Section 2.1. Revolving Loan 6 Section 2.2. Di

Amended Credit Agreement, dated as of October 3, 2022 and amended on September 6, 2023 and March 13, 2024, by and between the Company and Mattress Liquidators, Inc.

  Exhibit 10.1       CREDIT AGREEMENT   Dated as of October 3, 2022   IMMUNOGENX, INC. as Borrower   and   MATTRESS LIQUIDATORS, INC. as Lender             TABLE OF CONTENTS    Section Heading Page       SECTION 1. Definitions; Interpretation 1       Section 1.1. Definitions 1 Section 1.2. Interpretation 6       SECTION 2. The Credit Facilities 6       Section 2.1. Revolving Loan 6 Section 2.2. Di

Agreement and Plan of Merger, dated March 13, 2024, by and among First Wave BioPharma, Inc. IMMUNO Merger Sub I, Inc., IMMUNO Merger Sub II, LLC, and ImmunogenX, Inc.

Exhibit 2.1 Execution Version AGREEMENT AND PLAN OF MERGER among: FIRST WAVE BIOPHARMA, INC.; IMMUNO MERGER SUB I, INC.; IMMUNO MERGER SUB II, LLC; and IMMUNOGENX, INC. Dated as of March 13, 2024 TABLE OF CONTENTS Page Section 1. Definitions and Interpretative Provisions 3 1.1 Definitions 3 1.2 Other Definitional and Interpretative Provisions 14 Section 2. Description of Transaction 15 2.1 The Mer

Form of Placement Agency Agreement

Exhibit 10.1 PLACEMENT AGENCY AGREEMENT March 3, 2024 Roth Capital Partners, LLC 888 San Clemente Drive, Suite 400 Newport Beach, CA 92660 Ladies and Gentlemen: Introduction. Subject to the terms and conditions herein (this “Agreement”), First Wave BioPharma, Inc., a Delaware corporation (the “Company”), hereby agrees to sell up to an aggregate of $4,000,006.25 of registered securities of the Comp

Form of Placement Agency Agreement (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8-K filed with the SEC on March 5, 2024).

Exhibit 10.2 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of March 3, 2024, between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the terms and conditi

Form of Common Warrant (incorporated by reference to Exhibit 4.2 of the Company’s Current Report on Form 8-K filed with the SEC on March 5, 2024).

Exhibit 4.2 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTR

Form of Pre-Funded Warrant

Exhibit 4.1 PRE-FUNDED COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2024 THIS PRE-FUNDED COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date

First Wave BioPharma, Inc. to raise approximately $4.0 million of Gross Proceeds in Registered Direct Offering

Exhibit 99.1 First Wave BioPharma, Inc. to raise approximately $4.0 million of Gross Proceeds in Registered Direct Offering BOCA RATON, Fla., March 4, 2024 – First Wave BioPharma, Inc., (NASDAQ: FWBI), (“First Wave BioPharma” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (GI) diseases, announce

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Unregistered Sales of Equity Securities, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K 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 3, 2024 First Wave BioPharma, Inc.

173,100 Shares of Common Stock 352,525 Prefunded Warrants to Purchase up to 352,525 Shares of Common Stock 352,525 Shares of Common Stock underlying the Prefunded Warrants and

Filed Pursuant to Rule 424(b)(5) Registration No. 333-256476 PROSPECTUS SUPPLEMENT (To Prospectus Dated June 2, 2021) 173,100 Shares of Common Stock 352,525 Prefunded Warrants to Purchase up to 352,525 Shares of Common Stock 352,525 Shares of Common Stock underlying the Prefunded Warrants and We are offering 173,100 shares of our common stock, and prefunded warrants (the “Prefunded Warrants”) to p

FWBI / First Wave BioPharma, Inc. / ARMISTICE CAPITAL, LLC Passive Investment

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, DC 20549 SCHEDULE 13G/A Under the Securities Exchange Act of 1934 (Amendment No.

1,762,674 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-276429 PROSPECTUS 1,762,674 Shares of Common Stock This prospectus relates to the resale of up to 1,762,674 shares of First Wave BioPharma, Inc. (the “Company,” “we,” “our” or “us”) common stock, par value $0.0001 per share (the “Common Stock”), by the selling stockholders listed in this prospectus or their permitted transferees (the “Selling S

First Wave BioPharma, Inc. 777 Yamato Road, Suite 502 Boca Raton, Florida 33431 January 16, 2024

First Wave BioPharma, Inc. 777 Yamato Road, Suite 502 Boca Raton, Florida 33431 January 16, 2024 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance Office of Life Sciences 100 F Street, N.E. Washington, D.C. 20549 Attention: Jessica Dickerson Re: First Wave BioPharma, Inc. (the “Company”) Registration Statement on Form S-3 Filed on January 8, 2024 File No. 3

As filed with the Securities and Exchange Commission on January 8, 2024

As filed with the Securities and Exchange Commission on January 8, 2024 Registration No.

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) First Wave BioPharma, Inc.

First Wave BioPharma Chairman and CEO Issues Letter to Shareholders Highlighting Recent Accomplishments and Outlook for 2024 Multiple clinical and development milestones anticipated in 2024, including initiation of Phase 3 clinical trial investigatin

Exhibit 99.1 First Wave BioPharma Chairman and CEO Issues Letter to Shareholders Highlighting Recent Accomplishments and Outlook for 2024 Multiple clinical and development milestones anticipated in 2024, including initiation of Phase 3 clinical trial investigating latiglutenase in celiac disease in the event the company closes its potential merger transaction with ImmunogenX BOCA RATON, FL., Janua

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 4, 2024

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): January 4, 2024 First Wave BioPharma, Inc.

First Wave BioPharma, Inc. 777 Yamato Road, Suite 502 Boca Raton, Florida 33431

First Wave BioPharma, Inc. 777 Yamato Road, Suite 502 Boca Raton, Florida 33431 December 28, 2023 Via EDGAR U.S. Securities and Exchange Commission Division of Corporate Finance 100 F Street, N.E. Washington, D.C. 20549 Re: First Wave BioPharma, Inc. Request for Withdrawal of Registration Statement on Form S-1 File No. 333-275316 Ladies and Gentlemen: Pursuant to Rule 477 under the Securities Act

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 27, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 27, 2023 First Wave BioPharma, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 27, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 27, 2023 First Wave BioPharma, Inc.

Form of Inducement Warrant

Exhibit 4.1 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTR

First Wave BioPharma Announces Streamlining of Clinical Pipeline with Non-Binding Term Sheet to Sell Niclosamide IBD Program First Wave BioPharma to advance GI development pipeline with the expected addition of Phase 3 Latiglutenase celiac disease pr

Exhibit 99.1 First Wave BioPharma Announces Streamlining of Clinical Pipeline with Non-Binding Term Sheet to Sell Niclosamide IBD Program First Wave BioPharma to advance GI development pipeline with the expected addition of Phase 3 Latiglutenase celiac disease program and Phase 2 clinical programs built around Capeserod and Adrulipase BOCA RATON, FL, December 27, 2023 – First Wave BioPharma, Inc.,

Form of Inducement Letter

Exhibit 10.1 December 27, 2023 Armistice Capital Master Fund Ltd. c/o Armistice Capital, LLC 510 Madison Avenue, 7th Floor New York, NY 10022 Re: Reprice and Reload Offer of Common Stock Purchase Warrants To Whom It May Concern: First Wave BioPharma, Inc. (the “Company”) is pleased to offer to you the opportunity to receive new Common Stock purchase warrants of the Company in consideration for the

As filed with the Securities and Exchange Commission on December 27, 2023

As filed with the Securities and Exchange Commission on December 27, 2023 Registration No.

Form of Warrant Agency Agreement

Exhibit 4.40 FIRST WAVE BIOPHARMA, INC. and COLONIAL STOCK TRANSFER CO., INC. as Warrant Agent Warrant Agency Agreement Dated as of December [   ], 2023 WARRANT AGENCY AGREEMENT WARRANT AGENCY AGREEMENT, dated as of December [   ], 2023 (“Agreement”), between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and Colonial Stock Transfer Co., Inc. (the “Warrant Agent”). WITNESSETH

First Wave BioPharma Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $4.8 Million Gross Proceeds Priced

Exhibit 99.1 First Wave BioPharma Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $4.8 Million Gross Proceeds Priced BOCA RATON, Fla., December 27, 2023 (GLOBE NEWSWIRE) - First Wave BioPharma, Inc. (“First Wave BioPharma” or the “Company”) (NASDAQ: FWBI), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic the

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) First Wave BioPharma, Inc.

First Wave BioPharma Announces Entry into Term Sheet for Business Combination with ImmunogenX Establishing a Leading Late-Stage GI-Focused Biopharmaceutical Company Phase 3-ready latiglutenase, a targeted oral biotherapeutic for celiac disease, will

Exhibit 99.1 First Wave BioPharma Announces Entry into Term Sheet for Business Combination with ImmunogenX Establishing a Leading Late-Stage GI-Focused Biopharmaceutical Company Phase 3-ready latiglutenase, a targeted oral biotherapeutic for celiac disease, will expand First Wave BioPharma’s late-stage gastrointestinal (GI) disease clinical pipeline A concurrent institutional investment and a stra

Form of Placement Agency Agreement.

Exhibit 1.1 PLACEMENT AGENCY AGREEMENT [ ], 2023 Roth Capital Partners, LLC 888 San Clemente Drive, Suite 400 Newport Beach, CA 92660 Ladies and Gentlemen: Introduction. Subject to the terms and conditions herein (this “Agreement”), First Wave BioPharma, Inc., a Delaware corporation (the “Company”), hereby agrees to sell up to an aggregate of $[ ] of registered securities of the Company, including

Financial Statements and Exhibits, Other Events

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 18, 2023 First Wave BioPharma, Inc.

Form of Pre-Funded Warrant.

Exhibit 4.36 PRE-FUNDED COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2023 THIS PRE-FUNDED COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date

Form of Securities Purchase Agreement.

Exhibit 10.50 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of [ ], 2023, between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the terms and conditions

Form of Warrant Agency Agreement

Exhibit 4.38 FIRST WAVE BIOPHARMA, INC.. and COLONIAL STOCK TRANSFER CO., INC. as Warrant Agent Warrant Agency Agreement Dated as of December [], 2023 WARRANT AGENCY AGREEMENT WARRANT AGENCY AGREEMENT, dated as of December [], 2023 (“Agreement”), between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and Colonial Stock Transfer Co., Inc.(the “Warrant Agent”). WITNESSETH WHEREA

Form of Common Warrant.

Exhibit 4.37 COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2023 THIS COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date hereof (the “Initial

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) First Wave BioPharma, Inc.

As filed with the Securities and Exchange Commission on December 18, 2023

As filed with the Securities and Exchange Commission on December 18, 2023 Registration No.

Regulation FD Disclosure, Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year, Material Modification to Rights of Security Holders, Financial Statements and Exhibits, Submission of Matters to a Vote of Security Holders

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): December 12, 2023 First Wave BioPharma, Inc.

Certificate of Amendment to the Amended and Restated Certificate of Incorporation, as amended, of First Wave BioPharma, Inc. dated December 13, 2023 (incorporated by reference to Exhibit 3.1 of the Company’s Current Report on Form 8 - K filed with the SEC on December 14, 2023).

Exhibit 3.1 CERTIFICATE OF AMENDMENT TO THE AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF FIRST WAVE BIOPHARMA, INC. First Wave BioPharma, Inc. (the “Corporation”), a corporation organized and existing under and by virtue of the General Corporation Law of the State of Delaware, does hereby certify as follows: FIRST: That a resolution was duly adopted on December 6, 2023, by the Board of Dir

First Wave BioPharma Announces 1-for-20 Reverse Stock Split and Results of the Special Meeting of Stockholders

Exhibit 99.1 First Wave BioPharma Announces 1-for-20 Reverse Stock Split and Results of the Special Meeting of Stockholders BOCA RATON, Fla., Dec. 14, 2023 (GLOBE NEWSWIRE) – First Wave BioPharma, Inc. (NASDAQ: FWBI) (“First Wave BioPharma,” “First Wave” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointes

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant ☒ Filed by a Party other than the Registrant ☐ Check the appropriate box: ☐ Preliminary Proxy Statement ☐ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) ☐ Definitive Proxy Statement ☒

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) First Wave BioPharma, Inc.

As filed with the Securities and Exchange Commission on November 3, 2023

As filed with the Securities and Exchange Commission on November 3, 2023 Registration No.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. 1)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. 1) Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: x ¨ ¨ ¨ ¨ Preliminary Proxy Statement Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) Definit

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): October 26, 2023 First Wave BioPharma, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 Filed by the Registrant x Filed by a Party other than the Registrant ¨ Check the appropriate box: x ¨ ¨ ¨ ¨ Preliminary Proxy Statement Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) Definitive Proxy Statemen

License Agreement, dated September 13, 2023 (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on October 10, 2023).

Exhibit 10.1 CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THIS EXHIBIT BECAUSE IT IS BOTH (I) NOT MATERIAL AND (II) IS THE TYPE THAT THE COMPANY TREATS AS PRIVATE OR CONFIDENTIAL. THE REDACTED TERMS HAVE BEEN MARKED WITH THREE ASTERISKS [***] LICENSE AGREEMENT between SANOFI and FIRST WAVE BIOPHARMA, INC. Dated as of September 13, 2023 TABLE OF CONTENTS Article 1 DEFINITIONS 5 Article 2 G

Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K/A CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 13, 2023 First Wave BioPharma, Inc.

11,764,072 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-274634 PROSPECTUS 11,764,072 Shares of Common Stock This prospectus relates to the resale of up to 11,764,072 shares of First Wave BioPharma, Inc. (the “Company,” “we,” “our” or “us”) common stock, par value $0.0001 per share (the “Common Stock”), by the selling stockholders listed in this prospectus or their permitted transferees (the “Selling

September 28, 2023

September 28, 2023 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

As filed with the Securities and Exchange Commission on September 21, 2023

As filed with the Securities and Exchange Commission on September 21, 2023 Registration No.

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) First Wave BioPharma, Inc.

Form of Inducement Warrant (incorporated by reference to Exhibit 4.1 of the Current Report on Form 8-K filed with the SEC on September 15, 2023).

Exhibit 4.1 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTR

Entry into a Material Definitive Agreement, Material Modification to Rights of Security Holders, Unregistered Sales of Equity Securities, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 14, 2023 First Wave BioPharma, Inc.

Form of Inducement Letter (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on September 15, 2023).

Exhibit 10.1 September 14, 2023 [Name and address of warrant holder] Re: Reprice and Reload Offer of Common Stock Purchase Warrants To Whom It May Concern: First Wave BioPharma, Inc. (the “Company”) is pleased to offer to you the opportunity to receive new Common Stock purchase warrants of the Company in consideration for the exercise of the Common Stock purchase warrants issued to you on or about

First Wave BioPharma Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $4.0 Million Gross Proceeds Priced At-the-Market

Exhibit 99.1 First Wave BioPharma Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $4.0 Million Gross Proceeds Priced At-the-Market BOCA RATON, Fla., September 14, 2023 (GLOBE NEWSWIRE) - First Wave BioPharma, Inc. (“First Wave BioPharma” or the “Company”) (NASDAQ: FWBI), a clinical-stage biopharmaceutical company specializing in the development of targeted, n

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 13, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): September 13, 2023 First Wave BioPharma, Inc.

First Wave BioPharma Announces Exclusive Global License Agreement for Capeserod from Sanofi First Wave to develop and repurpose Capeserod for gastrointestinal (GI) indications based on AI-empowered analyses, expanding the company’s GI-focused pipelin

Exhibit 99.1 First Wave BioPharma Announces Exclusive Global License Agreement for Capeserod from Sanofi First Wave to develop and repurpose Capeserod for gastrointestinal (GI) indications based on AI-empowered analyses, expanding the company’s GI-focused pipeline BOCA RATON, Fla. September 14, 2023 - First Wave BioPharma, Inc., (NASDAQ:FWBI), (“First Wave” or the “Company”), a clinical-stage biop

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 24, 2023 First Wave BioPharma, Inc.

Calculation of Filing Fee Table.*

Exhibit 107 Calculation of Filing Fee Table Form S-8 (Form Type) First Wave BioPharma, Inc.

As filed with the Securities and Exchange Commission on August 21, 2023

As filed with the Securities and Exchange Commission on August 21, 2023 Registration No.

Notice of Delisting or Failure to Satisfy a Continued Listing Rule or Standard; Transfer of Listing

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): August 17, 2023 First Wave BioPharma, Inc.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001-3785

Form of Warrant (incorporated by reference to Exhibit 4.2 of the Company’s Current Report on Form 8-K filed with the SEC on July 21, 2023).

Exhibit 4.2 COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2023 THIS COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date hereof (the “Initial E

First Wave BioPharma, Inc. Announces Pricing of $2.1 Million Public Offering

Exhibit 99.1 First Wave BioPharma, Inc. Announces Pricing of $2.1 Million Public Offering BOCA RATON, Fla., July 19, 2023 – First Wave BioPharma, Inc. (NASDAQ:FWBI) (“First Wave BioPharma” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal diseases, today announced the pricing of a public offering o

Regulation FD Disclosure, Entry into a Material Definitive Agreement, Financial Statements and Exhibits

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 18, 2023 First Wave BioPharma, Inc.

Form of Placement Agency Agreement

Exhibit 10.1 PLACEMENT AGENCY AGREEMENT July 18, 2023 Roth Capital Partners, LLC 888 San Clemente Drive, Suite 400 Newport Beach, CA 92660 Ladies and Gentlemen: Introduction. Subject to the terms and conditions herein (this “Agreement”), First Wave BioPharma, Inc., a Delaware corporation (the “Company”), hereby agrees to sell up to an aggregate of $2,102,132.50 of registered securities of the Comp

Form of Pre-Funded Warrant (incorporated by reference to Exhibit 4.1 of the Company’s Current Report on Form 8-K filed with the SEC on July 21, 2023).

Exhibit 4.1 PRE-FUNDED COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2023 THIS PRE-FUNDED COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date

Form of Purchase Agreement (incorporated by reference to Exhibit 10.2 of the Company’s Current Report on Form 8-K filed with the SEC on July 21, 2023).

Exhibit 10.2 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of July 18, 2023, between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the terms and conditi

610,000 Shares of Common Stock Pre-Funded Warrants to Purchase up to 2,675,000 Shares of Common Stock 6,570,000 Common Warrants to Purchase up to 6,570,000 Shares of Common Stock 9,245,000 Shares of Common Stock underlying the Pre-Funded Warrants and

Filed Pursuant to Rule 424(b)(4) Registration No. 333-272404 PROSPECTUS 610,000 Shares of Common Stock Pre-Funded Warrants to Purchase up to 2,675,000 Shares of Common Stock 6,570,000 Common Warrants to Purchase up to 6,570,000 Shares of Common Stock 9,245,000 Shares of Common Stock underlying the Pre-Funded Warrants and Common Warrants We are offering up to 610,000 shares of common stock, togethe

July 14, 2023

July 14, 2023 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

Roth Capital Partners, LLC 888 San Clemente Drive Newport Beach, CA 92660

Roth Capital Partners, LLC 888 San Clemente Drive Newport Beach, CA 92660 July 14, 2023 Securities and Exchange Commission 100 F Street, N.

July 14, 2023

July 14, 2023 VIA FACSIMILE AND EDGAR U.S. Securities and Exchange Commission Division of Corporate Finance Washington, DC 20549 Re: First Wave BioPharma, Inc. Registration Statement on Form S-1 (Registration No. 333-272404), as amended – Withdrawal of Acceleration Request Ladies and Gentlemen: Reference is made to our letter, filed as correspondence via EDGAR on July 12, 2023, in which we, acting

July 14, 2023

July 14, 2023 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

July 13, 2023

July 13, 2023 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

First Wave BioPharma Announces Initial Topline Results from Phase 2 SPAN Clinical Trial Investigating Enhanced Adrulipase Formulation

Exhibit 99.1 First Wave BioPharma Announces Initial Topline Results from Phase 2 SPAN Clinical Trial Investigating Enhanced Adrulipase Formulation BOCA RATON, Fla. July 13, 2023 - First Wave BioPharma, Inc., (NASDAQ:FWBI), (“First Wave BioPharma” or the “Company”), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-systemic therapies for gastrointestinal (G

As filed with the Securities and Exchange Commission on July 13, 2023

As filed with the Securities and Exchange Commission on July 13, 2023 Registration No.

Roth Capital Partners, LLC 888 San Clemente Drive Newport Beach, CA 92660

Roth Capital Partners, LLC 888 San Clemente Drive Newport Beach, CA 92660 July 13, 2023 Securities and Exchange Commission 100 F Street, N.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 13, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): July 13, 2023 First Wave BioPharma, Inc.

As filed with the Securities and Exchange Commission on July 11, 2023

As filed with the Securities and Exchange Commission on July 11, 2023 Registration No.

First Wave BioPharma, Inc. 777 Yamato Road, Suite 502 Boca Raton, FL 33431 July 11, 2023

First Wave BioPharma, Inc. 777 Yamato Road, Suite 502 Boca Raton, FL 33431 July 11, 2023 VIA EDGAR Securities and Exchange Commission Division of Corporation Finance 100 F St, N.E. Washington, DC 20549 Attention: Lauren S. Hamill Re: First Wave BioPharma, Inc. Registration Statement on Form S-1 Filed June 5, 2023 File No. 333-272404 Dear Ms. Hamill: First Wave BioPharma, Inc. (the “Company”), is h

Form of Placement Agency Agreement.

Exhibit 1.1 PLACEMENT AGENCY AGREEMENT [], 2023 Roth Capital Partners, LLC 888 San Clemente Drive, Suite 400 Newport Beach, CA 92660 Ladies and Gentlemen: Introduction. Subject to the terms and conditions herein (this “Agreement”), First Wave BioPharma, Inc., a Delaware corporation (the “Company”), hereby agrees to sell up to an aggregate of $[] of registered securities of the Company, including,

Form of Securities Purchase Agreement.

Exhibit 10.46 SECURITIES PURCHASE AGREEMENT This Securities Purchase Agreement (this “Agreement”) is dated as of [], 2023, between First Wave BioPharma, Inc., a Delaware corporation (the “Company”), and each purchaser identified on the signature pages hereto (each, including its successors and assigns, a “Purchaser” and collectively, the “Purchasers”). WHEREAS, subject to the terms and conditions

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) First Wave BioPharma, Inc.

Form of Pre-Funded Warrant.

Exhibit 4.35 PRE-FUNDED COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2023 THIS PRE-FUNDED COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date

As filed with the Securities and Exchange Commission on July 6, 2023

As filed with the Securities and Exchange Commission on July 6, 2023 Registration No.

Form of Common Warrant (incorporated by reference to Exhibit 4.36 of the Company’s Amendment No. 1 to its Registration Statement on Form S-1 filed with the SEC on July 7, 2023).

Exhibit 4.36 COMMON STOCK PURCHASE WARRANT FIRST WAVE BIOPHARMA, INC. Warrant Shares: Initial Exercise Date: , 2023 THIS COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, or its assigns (the “Holder”) is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth, at any time on or after the date hereof (the “Initial

3,448,664 Shares of Common Stock

Filed Pursuant to Rule 424(b)(3) Registration No. 333-272783 PROSPECTUS 3,448,664 Shares of Common Stock This prospectus relates to the resale of up to 3,448,664 shares of First Wave BioPharma, Inc. (the “Company,” “we,” “our” or “us”) common stock, par value $0.0001 per share (the “Common Stock”), by the selling stockholders listed in this prospectus or their permitted transferees (the “Selling S

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 22, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 22, 2023 First Wave BioPharma, Inc.

Amendment to the 2020 Omnibus Equity Incentive Plan (incorporated by reference to the Company’s Current Report on Form 8 - K filed with the SEC on June 23, 2023).

Exhibit 10.1 AMENDMENT TO THE azurrx biopharma, inc. 2020 OMNIBUS EQUITY INCENTIVE PLAN Dated: April 20 , 2023 WHEREAS, the Board of Directors (the “Board”) of First Wave BioPharma, Inc. (formerly, AzurRx BioPharma, Inc.), a Delaware corporation (the “Company”) heretofore established the AzurRx BioPharma, Inc. 2020 Omnibus Equity Incentive Plan, as amended and restated as of August 11, 2020 (the “

June 23, 2023

June 23, 2023 VIA EDGAR United States Securities and Exchange Commission Division of Corporation Finance 100 F Street, N.

As filed with the Securities and Exchange Commission on June 20, 2023

As filed with the Securities and Exchange Commission on June 20, 2023 Registration No.

Filing Fee Table.

Exhibit 107 Calculation of Filing Fee Tables Form S-3 (Form Type) First Wave BioPharma, Inc.

First Wave BioPharma Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $2.4 Million Gross Proceeds Priced At-the-Market

Exhibit 99.1 First Wave BioPharma Announces Exercise of Warrants and Issuance of New Warrants in a Private Placement for $2.4 Million Gross Proceeds Priced At-the-Market BOCA RATON, Fla., June 13, 2023 (GLOBE NEWSWIRE) - First Wave BioPharma, Inc. ("First Wave BioPharma" or the “Company”) (NASDAQ: FWBI), a clinical-stage biopharmaceutical company specializing in the development of targeted, non-sy

Form of Inducement Warrant (incorporated by reference to Exhibit 4.1 of the Company’s Current Report on Form 8-K filed with the SEC on June 16, 2023).

Exhibit 4.1 NEITHER THIS SECURITY NOR THE SECURITIES FOR WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTR

Form of Inducement Letter (incorporated by reference to Exhibit 10.1 of the Company’s Current Report on Form 8-K filed with the SEC on June 16, 2023).

Exhibit 10.1 June 13, 2023 [Name and address of warrant holder] Re: Reprice and Reload Offer of Common Stock Purchase Warrants To Whom It May Concern: First Wave BioPharma, Inc. (the “Company”) is pleased to offer to you the opportunity to receive new Common Stock purchase warrants of the Company in consideration for the exercise of the Common Stock purchase warrants issued to you on or about Janu

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 13, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): June 13, 2023 First Wave BioPharma, Inc.

Filing Fee Table.

EX-FILING FEES 3 tm2317619d1ex-fillingfees.htm EX-FILING FEES Exhibit 107 Calculation of Filing Fee Tables S-1 (Form Type) First Wave BioPharma, Inc. (Exact Name of Registrant as Specified in its Charter) Table 1: Newly Registered and Carry Forward Securities Security Type Security Class Title Fee Calculation or Carry Forward Rule Amount Registered Proposed Maximum Offering Price Per Unit Maximum

As filed with the Securities and Exchange Commission on June 5, 2023

As filed with the Securities and Exchange Commission on June 5, 2023 Registration No.

our definitive proxy statement on Schedule 14A, filed on May 15, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 14A Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No.  ) Filed by the Registrant x Filed by a Party other than the Registrant  ¨ Check the appropriate box: ¨ Preliminary Proxy Statement ¨ Confidential, for Use of the SEC Only (as permitted by Rule 14a-6(e)(2)) x Definitive

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 OR ☐ TRANSITION REPORT UNDER SECTION 13 OF 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 From the transition period from to Commission File Number 001-378

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): April 20, 2023

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, DC 20549 FORM 8-K CURRENT REPORT Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of report (Date of earliest event reported): April 20, 2023 First Wave BioPharma, Inc.