Exhibit 10.16.2

Confidential Treatment Requested by Homology Medicines, Inc.

FIRST AMENDMENT TO LICENSE AGREEMENT

This amendment to the License Agreement (the “First License Amendment”), effective on the date last signed below, (“Amendment Effective Date”) is by and between Homology Medicines, Inc., a Delaware corporation having a place of business at 45 Wiggins Avenue, Bedford, MA 01730 (“HMI”) and California Institute of Technology, a not-for-profit corporation duly organized and existing under the laws of the State of California with an address at 1200 East California Boulevard, MC 6-32, Pasadena, California 91125 (“Caltech”; HMI and Caltech together are the “Parties”).

Whereas, HMI and Caltech entered into that certain License Agreement, effective September 9, 2016 (the “Agreement”);

Whereas, Caltech and the Co-exclusive Licensee, as defined by the Agreement, entered into a Co-exclusive License, as defined by the Agreement, that grants the same rights to the Co-exclusively Licensed Patent Rights, as defined in the Agreement, as those granted to HMI; and

Whereas, HMI and Caltech desire to amend the Agreement as set forth in this First License Amendment.

Now therefore, in consideration of the mutual covenants contained herein, and for other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the Parties agree as follows:

“Technology” means Verified [***], including reports

that detail or describe the Verification of [***], from the laboratories Professor [***] or Professor [***] that are provided to Licensee by Caltech pursuant to this Agreement, whether or not patentable, and as set forth in Exhibit B, as the same may be updated from time to time pursuant to Section 7.3.

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Confidential Portions of this Exhibit marked as [***] have been omitted pursuant to a request for confidential treatment and have been filed separately with the Securities and Exchange Commission

Confidential Treatment Requested by Homology Medicines, Inc.

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“9.1A Caltech hereby covenants, represents and warrants to Licensee:

(a) that the Co-exclusive Licensee to the Co-Exclusively Licensed Patent Rights will, or has already, entered into an identical first amendment to their Co-exclusive License (the “Third Party First Amendment”), and that said Third Party First Amendment shall have the same effect on the Co-exclusive License as those amendments herein shall have on the Agreement;

(b) that Caltech has secured Caltech’s ownership rights for the Licensed Patent Rights, as defined in the Agreement, including the rights afforded by Professor [***] as an inventor, and that [***] has assigned to Caltech all her right, title and interest in the Licensed Patent Rights;

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Confidential Portions of this Exhibit marked as [***] have been omitted pursuant to a request for confidential treatment and have been filed separately with the Securities and Exchange Commission

Confidential Treatment Requested by Homology Medicines, Inc.

(c) that Caltech will add [***] as an inventor to certain patent applications in the Licensed Patent Rights as indicated in Exhibit A (Amended) and that, upon such addition, the inventorship of the patents and patent applications in the Licensed Patent Rights will be correct to the best of Caltech’s Office of Technology Transfer & Corporate Partnerships knowledge;

(d) that all Technology developed in the laboratories of Professor [***] or Professor [***] as of the date thirty (30) days after the Effective Date has been provided to Licensee in accordance with Section 7.3.

“Licensee agrees not to disclose Technology or reports provided pursuant to Section 7.3 to any third party except to the extent the information therein has been published, provided that Licensee may disclose such Technology and/or reports, and/or the terms of this Agreement, to actual or potential investors, actual or potential strategic partners, Affiliates, Sublicensees, consultants, contractors or those under reasonable confidentiality obligations and whose receipt of said information is necessary for Licensee’s business activities.”

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Confidential Portions of this Exhibit marked as [***] have been omitted pursuant to a request for confidential treatment and have been filed separately with the Securities and Exchange Commission

Confidential Treatment Requested by Homology Medicines, Inc.

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Confidential Portions of this Exhibit marked as [***] have been omitted pursuant to a request for confidential treatment and have been filed separately with the Securities and Exchange Commission

Confidential Treatment Requested by Homology Medicines, Inc.

In witness whereof, the duly authorized representatives of each of the parties hereto executed this First License Amendment.

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Confidential Portions of this Exhibit marked as [***] have been omitted pursuant to a request for confidential treatment and have been filed separately with the Securities and Exchange Commission

Confidential Treatment Requested by Homology Medicines, Inc.

Exhibit A (Amended)

Licensed Patent Rights

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First License Amendment | HMI | A3916-1

Confidential Portions of this Exhibit marked as [***] have been omitted pursuant to a request for confidential treatment and have been filed separately with the Securities and Exchange Commission