Exhibit 10.1

[***] Certain information in this document has been omitted from this exhibit
because it is both (i) not material and (ii) would be competitively harmful if
publicly disclosed.

AMENDMENT #1

TO

PROJECT RIDER #3

COLLABORATION AGREEMENT

This Amendment #1 (“Amendment #1”) is entered into effective as of the date of
the final signature executing this Amendment #1 (“Amendment #1 Effective Date”),
by and between Magenta Therapeutics, Inc. (“Magenta”) and National Marrow Donor
Program d/b/a Be The Match Biotherapies (“BTMB”), (each a “Party” and
collectively the “Parties”) as those Parties are defined in Attachment A,
Project Rider #3, effective September 6, 2018 (collectively, the “Project Rider
#3”).

WHEREAS, the Parties executed a Collaboration Agreement, effective November 10,
2017, and Project Rider #3, effective September 6, 2018; and

WHEREAS, the Parties agree to extend the term of the Project Rider #3.

NOW, THEREFORE, for the valuable consideration contained herein, and intending
to be legally bound, Magenta and BTMB agree to the following amendment to be
effective as of the Amendment #1 Effective Date as follows:

Amendment to Project Rider #3

 

  1.

Delete the current term in Section D. Term of Project Rider #3 in its entirety
and replace it with the following to read as follows:

“The term of this Rider shall commence on the Rider effective date set forth
above and continue in effect through [***].”

This Amendment #1 is executed by individuals who are duly authorized to legally
bind their respective parties as of the Amendment #1 Effective Date:

 

MAGENTA THERAPEUTICS, INC.     NATIONAL MARROW DONOR PROGRAM d/b/a BE THE MATCH
BIOTHERAPIES By:  

/s/ Angelene Simonello

    By:  

/s/ Mary Frey

  Authorized Signature       Authorized Signature  

Angelene Simonello

     

Mary Frey

  (Typed/Printed Name)       (Typed/Printed Name) Title:   VP Program Lead    
Title:   Contracts & Procurement Director Date:   8/26/19     Date:   8/21/19