CUSIP No. 162818108 13G Exhibit 99.1

AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree that only one statement containing the information required by Schedule 13G need be filed with respect to the ownership by each of the undersigned of Common Stock of Checkmate Pharmaceuticals, Inc.

Dated:	February 12, 2021
OMEGA FUND VI, L.P.
BY:	Omega Fund VI GP, L.P.
ITS:	GENERAL PARTNER
BY:	Omega Fund VI GP Manager, Ltd.
ITS:	GENERAL PARTNER
By:	/s/ * Deirdre A. Cunnane, as Attorney-in-Fact
	Director
OMEGA FUND VI GP, L.P.
BY:	Omega Fund VI GP Manager, Ltd.
ITS:	GENERAL PARTNER
By:	/s/ * Deirdre A. Cunnane, as Attorney-in-Fact
	Director
OMEGA FUND VI GP MANAGER, LTD.
By:	/s/ * Deirdre A. Cunnane, as Attorney-in-Fact
	Director
/s/ * Deirdre A. Cunnane, as Attorney-in-Fact Claudio Nessi
/s/ * Deirdre A. Cunnane, as Attorney-in-Fact Otello Stampacchia
/s/ * Deirdre A. Cunnane, as Attorney-in-Fact Anne-Mari Paster