AGREEMENT

Exhibit 99.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 Alpine Immune Systems, Inc.

Date: September 21, 2021				XXXXXXX LIFE SCIENCES VIII, L.P.
				By FHM Life Sciences VIII, L.P., its general partner
				By FHM Life Sciences VIII, L.L.C., its general partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer

Date: September 21, 2021				FHM LIFE SCIENCES VIII, L.P.
				By FHM Life Sciences VIII, L.L.C., its general partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer

Date: September 21, 2021				FHM LIFE SCIENCES VIII, L.L.C.
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer

Date: September 21, 2021				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: September 21, 2021				FHMLSP, L.P.
				By: FHMLSP, L.L.C., its General Partner
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer

Date: September 21, 2021				FHMLSP, L.L.C.
				By:		/s/ Xxxxx X. Xxxxxx
						Xxxxx X. Xxxxxx, Chief Financial Officer

Date: September 21, 2021				By:		*
						Xxxxx X. Xxxxxx

Date: September 21, 2021				By:		*
						Xxxxxxx X. Xxxxx

Date: September 21, 2021				By:		**
						Xxxxxx Xxx

Date: September 21, 2021				By:		**
						Xxxxx Xxxxx

Date: September 21, 2021				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 July 31, 2017.

** 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.