Exhibit A

AGREEMENT REGARDING THE JOINT FILING OF

SCHEDULE 13G

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

Date: February 12, 2020

POLARIS PARTNERS VII, L.P.
By:	Polaris Management Co. VII, L.L.C.
By:	**
	Authorized Signatory
POLARIS ENTREPRENEURS’ FUND VII, L.P.
By:	Polaris Management Co. VII, L.L.C.
By:	**
	Authorized Signatory
POLARIS MANAGEMENT CO. VII, L.L.C.
By:	**
	Authorized Signatory
BRYCE YOUNGREN
By:	*
	Bryce Youngren
DAVID BARRETT
By:	*
	David Barrett
BRIAN CHEE
By:	*
	Brian Chee
AMIR NASHAT
By:	*
	Amir Nashat

*By:	/s/ Lauren Crockett
Name:	Lauren Crockett
	Attorney-in-Fact

[*This Schedule 13G was executed pursuant to a Power of Attorney. Note that copies of the applicable Powers of Attorney are already on file with the appropriate agencies.]

[**This Schedule 13G was executed pursuant to a Power of Attorney. Note that copies of the applicable Powers of Attorney are included as exhibits to this Schedule 13G.]