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 13D need be filed with respect to the ownership by each of the undersigned of Common Stock of Phathom Pharmaceuticals, Inc.

Date: May 26, 2023	FRAZIER LIFE SCIENCES IX, L.P.
	By FHMLS IX, L.P., its general partner
	By FHMLS IX, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 26, 2023	FHMLS IX, L.P.
	By FHMLS IX, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 26, 2023	FHMLS IX, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 26, 2023	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: May 26, 2023	FHMLSP, L.P.
	By:	FHMLSP, L.L.C., its General Partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer

Date: May 26, 2023	FHMLSP, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 26, 2023	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: May 26, 2023	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: May 26, 2023	FHMLSP OVERAGE, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 26, 2023	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: May 26, 2023	FHMLS XI, L.P.
	By FHMLS XI, L.L.C., its general partner
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer

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Date: May 26, 2023	FHMLS XI, L.L.C.
	By:	/s/ Steve R. Bailey
		Steve R. Bailey, Chief Financial Officer
Date: May 26, 2023	By:	*
		James Topper
Date: May 26, 2023	By:	*
		Patrick Heron
Date: May 26, 2023	By:	**
		Albert Cha
Date: May 26, 2023	By:	**
		James Brush
Date: May 26, 2023	By:	***
		Daniel Estes
Date: May 26, 2023	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 July 31, 2017.

** 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 individual listed above pursuant to a Power of Attorney, a copy of which was filed with the SEC on April 18, 2022.

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