Contract

Exhibit A

The undersigned hereby agree that the statement on Schedule 13D to which this Agreement is annexed as Exhibit 1, and any amendments thereto, is and will be filed on behalf of each of them in accordance with the provisions of Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended.

April 1, 2016		VIVO VENTURES VI, LLC
				By:		/s/ Xxxxx Xxxx
						Xxxxx Xxxx
						Managing Member
				VIVO VENTURES FUND VI, L.P.
				By:  Vivo Ventures VI, LLC
				Its:   General Partner
				By:		/s/ Xxxxx Xxxx
						Xxxxx Xxxx
						Managing Member
				VIVO VENTURES VI AFFILIATES FUND, L.P.
				By:  Vivo Ventures VI, LLC
				Its:   General Partner
				By:		/s/ Xxxxx Xxxx
						Xxxxx Xxxx
						Managing Member