Exhibit A

JOINT FILING AGREEMENT

The undersigned agree that this Schedule 13G dated January 6, 2025 relating to the Common Stock, par value $0.001 per share, of Fulcrum Therapeutics, Inc. shall be filed on behalf of the undersigned.

SUVRETTA CAPITAL MANAGEMENT, LLC

By: /s/ Aaron Cowen

Name: Aaron Cowen

Title:   Authorized Signatory

AVERILL MASTER FUND, LTD.

By: /s/ Aaron Cowen

Name: Aaron Cowen

Title:   Director

AARON COWEN

By: /s/ Aaron Cowen