CUSIP No. 38341P102 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 Gossamer Bio, Inc.

Dated: February 12, 2021

OMEGA FUND V, L.P.
BY:	Omega Fund V GP, L.P.
ITS:	GENERAL PARTNER
BY:	Omega Fund V GP Manager, Ltd.
ITS:	GENERAL PARTNER
By:	/s/ * Deirdre A. Cunnane, as Attorney-in-Fact
	Director
OMEGA FUND V GP, L.P.
BY:	Omega Fund V GP Manager, Ltd.
ITS:	GENERAL PARTNER
By:	/s/ * Deirdre A. Cunnane, as Attorney-in-Fact
	Director
OMEGA FUND V 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