First Amendment to Loan and Security Agreement, dated December 30, 2021, by and between Q32 Bio Inc. and Silicon Valley Bank

Exhibit 10.51

FIRST AMENDMENT

TO

LOAN AND SECURITY AGREEMENT

This First Amendment to Loan and Security Agreement (this “Amendment”) is entered into this 30^th day of December, 2021 by and between SILICON VALLEY BANK (“Bank”) and Q32 BIO INC., a Delaware a corporation (“Borrower”) whose address is One Broadway, 11^th Floor, Cambridge, Massachusetts 02142.

RECITALS

A. Bank and Borrower have entered into that certain Loan and Security Agreement dated as of December 11, 2020 (as the same may from time to time be amended, modified, supplemented or restated, the “Loan Agreement”).

B. Bank has extended credit to Borrower for the purposes permitted in the Loan Agreement.

C. Borrower has requested that Bank amend the Loan Agreement to make certain revisions to the Loan Agreement as more fully set forth herein.

D. Bank has agreed to so amend certain provisions of the Loan Agreement, but only to the extent, in accordance with the terms, subject to the conditions and in reliance upon the representations and warranties set forth below.

AGREEMENT

NOW, THEREFORE, in consideration of the foregoing recitals and other good and valuable consideration, the receipt and adequacy of which is hereby acknowledged, and intending to be legally bound, the parties hereto agree as follows:

1. Definitions. Capitalized terms used but not defined in this Amendment shall have the meanings given to them in the Loan Agreement.

2. Amendments to Loan Agreement.

2.1 Section 13.1 (Definitions). The following terms and their respective definitions set forth in Section 13.1 are amended in their entirety and replaced with the following:

“ “Draw Period 1” is the period of time commencing upon the Effective Date and continuing through the earlier to occur of (a) January 31, 2022, or (b) an Event of Default.

“ “Draw Period 2” is the period of time commencing upon the occurrence of Performance Milestone I and continuing through the earlier to occur of (a) April 30, 2022, or (b) an Event of Default.”

“ “Performance Milestone I” occurs if and when (if ever) Bank confirms in writing that it has received evidence, on or prior to April 30, 2022, satisfactory to Bank in Bank’s sole and absolute discretion, that each of the following has occurred on or prior to April 30, 2022: (i) the enrollment of Borrower’s first subject in the phase 1 clinical trial of ADX-097, and (ii) the initiation and continuation of Borrower’s phase 1 clinical trial of ADX-914.”

3. Limitation of Amendments.

3.1 The amendments set forth in Section 2 above are effective for the purposes set forth herein and shall be limited precisely as written and shall not be deemed to (a) be a consent to any amendment, waiver or modification of any other term or condition of any Loan Document, or (b) otherwise prejudice any right or remedy which Bank may now have or may have in the future under or in connection with any Loan Document.

3.2 This Amendment shall be construed in connection with and as part of the Loan Documents and all terms, conditions, representations, warranties, covenants and agreements set forth in the Loan Documents, except as herein amended, are hereby ratified and confirmed and shall remain in full force and effect.

4. Representations and Warranties. To induce Bank to enter into this Amendment, Borrower hereby represents and warrants to Bank as follows:

4.1 Immediately after giving effect to this Amendment (a) the representations and warranties contained in the Loan Documents are true, accurate and complete in all material respects as of the date hereof (except to the extent such representations and warranties relate to an earlier date, in which case they are true and correct in all material respects as of such date), and (b) no Event of Default has occurred and is continuing;

4.2 Borrower has the power and authority to execute and deliver this Amendment and to perform its obligations under the Loan Agreement, as amended by this Amendment;

4.3 The organizational documents of Borrower delivered to Bank on the Effective Date remain true, accurate and complete and have not been amended, supplemented or restated and are and continue to be in full force and effect;

4.4 The execution and delivery by Borrower of this Amendment and the performance by Borrower of its obligations under the Loan Agreement, as amended by this Amendment, have been duly authorized;

4.5 The execution and delivery by Borrower of this Amendment and the performance by Borrower of its obligations under the Loan Agreement, as amended by this Amendment, do not and will not contravene (a) any law or regulation binding on or affecting Borrower, (b) any contractual restriction with a Person binding on Borrower, (c) any order, judgment or decree of any court or other governmental or public body or authority, or subdivision thereof, binding on Borrower, or (d) the organizational documents of Borrower;

4.6 The execution and delivery by Borrower of this Amendment and the performance by Borrower of its obligations under the Loan Agreement, as amended by this Amendment, do not require any order, consent, approval, license, authorization or validation of, or filing, recording or registration with, or exemption by any governmental or public body or authority, or subdivision thereof, binding on Borrower, except as already has been obtained or made; and

4.7 This Amendment has been duly executed and delivered by Borrower and is the binding obligation of Borrower, enforceable against Borrower in accordance with its terms, except as such enforceability may be limited by bankruptcy, insolvency, reorganization, liquidation, moratorium or other similar laws of general application relating to or affecting creditors’ rights and by general equitable principles.

5. Updated Perfection Certificate. Borrower has delivered an updated Perfection Certificate in connection with this Amendment (the “Updated Perfection Certificate”) dated as of the date hereof, which Updated Perfection Certificate shall supersede in all respects that certain Perfection Certificate dated as of December 11, 2020. Borrower agrees that all references in the Loan Agreement to “Perfection Certificate” shall hereinafter be deemed to be a reference to the Updated Perfection Certificate.

6. Integration. This Amendment and the Loan Documents represent the entire agreement about this subject matter and supersede prior negotiations or agreements. All prior agreements, understandings, representations, warranties, and negotiations between the parties about the subject matter of this Amendment and the Loan Documents merge into this Amendment and the Loan Documents.

7. Counterparts. This Amendment may be executed in any number of counterparts and all of such counterparts taken together shall be deemed to constitute one and the same instrument.

8. Effectiveness. This Amendment shall be deemed effective upon (a) the due execution and delivery to Bank of this Amendment by each party hereto (other than Bank), (b) Borrower’s payment to Bank of Bank’s reasonable documented legal fees and expenses incurred in connection with this Amendment.

[Signature page follows.]

IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed and delivered as of the date first written above.