AGREEMENT REGARDING THE JOINT FILING OF SCHEDULE 13D

EXHIBIT A

AGREEMENT REGARDING THE JOINT FILING OF

SCHEDULE 13D

The undersigned being duly authorized thereunto, hereby execute this agreement as an exhibit to this Schedule 13D to evidence the agreement of the below-named parties, in accordance with the rules promulgated pursuant to the Securities Exchange Act of 1934, as amended, to file this Schedule (including amendments thereto) jointly on behalf of each such party.

Dated: July 3, 2018

Xxxx Capital Life Sciences Fund, L.P.
By: Xxxx Capital Life Sciences Partners, LP, its general partner
By: Xxxx Capital Life Sciences Investors, LLC, its general partner
By:		/s/ Xxxx Xxxxxx
Name:		Xxxx Xxxxxx
Title:		Managing Director

BCIP Life Sciences Associates, LP
By: Boylston Coinvestors, LLC, its general partner
By:		/s/ Xxxx Xxxxxx
Name:		Xxxx Xxxxxx
Title:		Authorized Signatory