EXHIBIT A

AGREEMENT

Pursuant to Rule 13d-1(k)(1) under the Securities Exchange Act of 1934, 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 Theseus Pharmaceuticals, Inc.

Date: February 13, 2024	FRAZIER LIFE SCIENCES PUBLIC FUND, L.P.
	By: FHMLSP, L.P., its General Partner
	By: FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FHMLSP, L.P.
	By: FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FHMLSP, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FRAZIER LIFE SCIENCES PUBLIC OVERAGE FUND, L.P.
	By: FHMLSP Overage, L.P., its General Partner
	By: FHMLSP Overage, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FHMLSP OVERAGE, L.P.
	By FHMLSP Overage, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FHMLSP OVERAGE, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FRAZIER LIFE SCIENCES XI, L.P.
	By: FHMLS XI, L.P., its General Partner
	By: FHMLS XI, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer

Date: February 13, 2024	FHMLS XI, L.P.
	By: FHMLS XI, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	FHMLS XI, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: February 13, 2024	By:	*
		James N. Topper
Date: February 13, 2024	By:	*
		Patrick J. Heron
Date: February 13, 2024	By:	**
		Albert Cha
Date: February 13, 2024	By:	**
		James Brush
Date: February 13, 2024	By:	***
		Daniel Estes
Date: February 13, 2024	By:	/s/ Steve R. Bailey
		Steve R. Bailey, as Attorney-in-Fact

* This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on March 29, 2016.

** This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021.

*** This Agreement was executed by Steve R. Bailey on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on April 18, 2022.