Joint Filer Information

Names:	Deerfield Mgmt HIF, L.P., Deerfield Mgmt III, L.P.,  Deerfield Management Company, L.P., Deerfield Healthcare Innovations Fund, L.P. and Deerfield Private Design Fund III, L.P.
Address:	780 Third Avenue, 37th Floor New York, NY  10017
Designated Filer:	James E. Flynn
Issuer and Ticker Symbol:	Editas Medicine, Inc.  [EDIT]
Date of Event Requiring Statement:	February 8, 2016

The undersigned, Deerfield Mgmt HIF, L.P., Deerfield Mgmt III, L.P., Deerfield Management Company, L.P., Deerfield Healthcare Innovations Fund, L.P. and  Deerfield Private Design Fund III, L.P. are jointly filing the attached Statement of Changes in Beneficial Ownership on Form 4 with James E. Flynn with respect to the beneficial ownership of securities of Editas Medicine, Inc.

Signatures:

DEERFIELD MGMT HIF, L.P. By:  J.E. Flynn Capital HIF, LLC, General Partner By: /s/ Jonathan Isler        Jonathan Isler, Attorney-In-Fact	DEERFIELD MGMT III, L.P. By:  J.E. Flynn Capital III, LLC, General Partner By: /s/ Jonathan Isler        Jonathan Isler, Attorney-In-Fact
DEERFIELD MANAGEMENT COMPANY, L.P. By:  Flynn Management LLC, General Partner By: /s/ Jonathan Isler        Jonathan Isler, Attorney-In-Fact	DEERFIELD PRIVATE DESIGN FUND III, L.P. By:  Deerfield Mgmt III, L.P., General Partner By:  J.E. Flynn Capital III, LLC, General Partner By: /s/ Jonathan Isler        Jonathan Isler, Attorney-In-Fact
DEERFIELD HEALTHCARE INNOVATIONS FUND, L.P. By:  Deerfield Mgmt HIF, L.P., General Partner By:  J.E. Flynn Capital HIF, LLC, General Partner By: /s/ Jonathan Isler        Jonathan Isler, Attorney-In-Fact