Exhibit 2.1

AMENDMENT TO BUSINESS COMBINATION AGREEMENT

THIS AMENDMENT TO BUSINESS COMBINATION AGREEMENT (this “Amendment”) is made as of February 10, 2023 (the “Amendment Date”) by and among Mountain Crest Acquisition Corp. V, a Delaware corporation (“SPAC”), AUM Biosciences Limited, a Cayman Islands exempted company (“Holdco”), AUM Biosciences Subsidiary Pte. Ltd., a private company limited by shares incorporated in Singapore, with company registration number 202238778Z and a direct wholly-owned subsidiary of Holdco (“Amalgamation Sub”), AUM Biosciences Delaware Merger Sub, Inc., a Delaware corporation and a direct wholly-owned subsidiary of Holdco (“Merger Sub”), and AUM Biosciences Pte. Ltd., a private company limited by shares incorporated in Singapore, with company registration number 201810204D (the “Company”). Each of SPAC, the Company, Holdco, Amalgamation Sub and Merger Sub shall individually be referred to herein as a “Party” and, collectively, the “Parties.” Capitalized terms used herein and not otherwise defined shall have the meanings ascribed to them in the Agreement (as defined below).

WHEREAS, SPAC and the Company entered into that certain Business Combination Agreement dated as of October 19, 2022 (as may be amended, restated, supplemented or otherwise modified from time to time in accordance with the terms thereof, the “Agreement”);

WHEREAS, the Parties entered into that certain joinder agreement dated as of January 27, 2023, pursuant to which Holdco, Amalgamation Sub and Merger Sub joined the Agreement as parties;

WHEREAS, pursuant to Section 11.11 of the Agreement, the Agreement may be amended in whole or in part, by a duly authorized agreement in writing executed in the same manner as the Agreement and which makes reference to the Agreement; and

WHEREAS, the Parties wish to amend the Agreement as set forth in this Amendment.

NOW, THEREFORE, intending to be legally bound and in consideration of the mutual provisions set forth in this Amendment and the Agreement and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Parties hereby agree as follows:

ARTICLE 1

AMENDMENT TO THE AGREEMENT

Section 1.1 Amendment to Section 10.1(e) of the Agreement. The date February 15, 2023 with respect to the defined term “Outside Date” in Section 10.1(e) of the Agreement is hereby deleted and shall be replaced with “May 15, 2023.”

ARTICLE 2

MISCELLANEOUS

Section 2.1 No Other Amendment. Except to the extent that any provisions of or any Exhibits or Schedules to the Agreement are expressly amended by Article 1 of this Amendment, all terms and conditions of the Agreement and all other documents, instruments and agreements executed thereunder, shall remain in full force and effect pursuant to the terms thereof. In the event of any inconsistency or contradiction between the terms of this Amendment and the Agreement, the provisions of this Amendment shall prevail and control.

Section 2.2 Reference to the Agreement. On and after the date hereof, each reference in the Agreement to “this Agreement,” “hereof,” “herein,” “herewith,” “hereunder” and words of similar import shall, unless otherwise stated, be construed to refer to the Agreement as amended by this Amendment. No reference to this Amendment need be made in any instrument or document at any time referring to the Agreement and a reference to the Agreement in any such instrument or document shall be deemed to be a reference to the Agreement as amended by this Amendment.

[Signature Page Follows]

2

IN WITNESS WHEREOF, the Parties have caused this Agreement to be executed as of the date first written above by their respective officers thereunto duly authorized.

SPAC:
MOUNTAIN CREST ACQUISITION CORP. V
By:	/s/ Suying Liu
Name:	Suying Liu
Title:	Chief Executive Officer
COMPANY:
AUM BIOSCIENCES PTE. LTD.
By	/s/ Vishal Doshi
Name:	Vishal Doshi
Title:	Chairman and Chief Executive Officer
HOLDCO:
AUM BIOSCIENCES LIMITED
By:	/s/ Vishal Doshi
Name:	Vishal Doshi
Title:	Director
AMALGAMATION SUB:
AUM BIOSCIENCES SUBSIDIARY PTE. LTD.
By:	/s/ Vishal Doshi
Name:	Vishal Doshi
Title:	Director
MERGER SUB:
AUM BIOSCIENCES DELAWARE MERGER SUB, INC.
By:	/s/ Vishal Doshi
Name:	Vishal Doshi
Title:	Director

[Signature Page to the Amendment to the Business Combination Agreement]

3