Amendment No. 1 to Exclusive License Agreement, dated as of September 10, 2014, by and between the Mayo Foundation for Medical Education and Research and Unity Biotechnology, Inc

Exhibit 10.19(b)

AMENDMENT NO. 1 TO EXCLUSIVE LICENSE AGREEMENT

THIS Amendment No.1 to Exclusive License Agreement (“Amendment”) is made and entered into this 10^th day of September 2014 (“Effective Date”), by and between the Mayo Foundation for Medical Education and Research (“Mayo”) having its principal place of business at 200 First Street SW, Rochester, MN 55905, and Cenexys, Inc., a Delaware corporation, having a place of business at 1700 Owen Street, Suite 535 San Francisco, CA 94158 (“Company”), for purposes of confirming the parties’ intent and agreement as set forth herein.

BACKGROUND

May and Company are parties to an Exclusive License Agreement, with an effective date of the 28^th day of June, 2013 (“Agreement”), which confirms the parties’ intent and agreement to grant an exclusive license to Mayo’s certain patent rights and a nonexclusive license to certain know-how. Mayo and Company wish to amend the Agreement as set forth in this Amendment No. 1, and, accordingly, Mayo and Company agree as follows:

AMENDED TERMS

Exhibit A in its entirety will be deleted and replaced with the exhibit attached to this Amendment No. 1.

All other terms of the Agreement shall remain in full force and effect for the term of the Agreement and as set forth in the Agreement.

IN WITNESS WHEREOF, Mayo and Company hereby enter into this Amendment No. 1, effective as of the date first set forth above.

[***] Certain information in this document has been omitted and filed separately with the Securities and Exchange Commission. Confidential treatment has been requested with respect to the omitted portions.

EXHIBIT A

PATENT RIGH

[***]

[***] Certain information in this document has been omitted and filed separately with the Securities and Exchange Commission. Confidential treatment has been requested with respect to the omitted portions.