AGREEMENT

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: January 23, 2023				XXXXXXX LIFE SCIENCES PUBLIC FUND, L.P.
				By:		FHMLSP, L.P., its General Partner
				By:		FHMLSP, L.L.C., its General Partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				FHMLSP, L.P.
				By:		FHMLSP, L.L.C., its General Partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				FHMLSP, L.L.C.
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				XXXXXXX 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/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				FHMLSP OVERAGE, L.P.
				By FHMLSP Overage, L.L.C., its General Partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				FHMLSP OVERAGE, L.L.C.
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				XXXXXXX LIFE SCIENCES XI, L.P.
				By:		FHMLS XI, L.P., its General Partner
				By:		FHMLS XI, L.L.C., its General Partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer

Date: January 23, 2023				FHMLS XI, L.P.
				By:		FHMLS XI, L.L.C., its General Partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				FHMLS XI, L.L.C.
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer
Date: January 23, 2023				By:		*
						Xxxxx X. Xxxxxx
Date: January 23, 2023				By:		*
						Xxxxxxx X. Xxxxx
Date: January 23, 2023				By:		**
						Xxxxxx Xxx
Date: January 23, 2023				By:		**
						Xxxxx Xxxxx
Date: January 23, 2023				By:		***
						Xxxxxx Xxxxx
Date: January 23, 2023				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, as Attorney-in-Fact

* This Agreement was executed by Xxxxx X. Xxxxxx 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 Xxxxx X. Xxxxxx 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 Xxxxx X. Xxxxxx 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.