Sangamo Receives FDA Acceptance for Rolling BLA Submission of AAV Gene Therapy ST-920 for Fabry Disease

RICHMOND, Calif. – November 21, 2025 — Sangamo Therapeutics, Inc. (Nasdaq: SGMO), a genomic medicine company, today announced that the U.S. Food and Drug Administration (FDA) has accepted the company’s request for a rolling submission and review of the Biologics License Application (BLA) for isaralgagene civaparvovec (ST-920).

ST-920 is a wholly owned investigational AAV (adeno-associated virus) gene therapy designed as a one-time, durable treatment for adults with Fabry disease. This acceptance facilitates an expedited path to potential market approval.

Accelerated Approval Pathway Confirmed

The FDA’s acceptance follows a meeting in October 2025 where the agency reaffirmed its agreement to use estimated glomerular filtration rate (eGFR) slope as the primary endpoint to support an accelerated approval pathway. This specific endpoint is crucial for demonstrating clinical benefit in a disease that causes serious damage to vital organs, particularly the kidney.

• STAAR Study Data: Detailed clinical data from the registrational Phase 1/2 STAAR study, presented in September, demonstrated ST-920’s potential to provide meaningful, multi-organ clinical benefits above current standards of care.
• Key Finding: The study demonstrated a positive mean annualized eGFR slope at 52-weeks across all dosed patients, supporting the gene therapy’s effectiveness in addressing underlying Fabry disease pathology.

“We are excited by the potential of ST-920 to provide a potentially transformative treatment for Fabry disease patients and look forward to initiating rolling submission of the BLA later this quarter,” said Nathalie Dubois-Stringfellow, Ph. D, Chief Development Officer at Sangamo.

Regulatory Designations Highlight Urgency

The AAV gene therapy has received multiple designations underscoring the high unmet medical need for Fabry patients:

• FDA: Orphan Drug, Fast Track, and RMAT designations.
• Europe/UK: Orphan Medicinal Product designation and PRIME eligibility from the European Medicines Agency (EMA), and Innovative Licensing and Access Pathway from the U.K. Medicines and Healthcare products Regulatory Agency (MHRA).

Sangamo plans to initiate the rolling submission of the BLA to the FDA under the accelerated approval pathway later in the fourth quarter of 2025. ST-920 is administered as a single, one-time AAV infusion without the need for preconditioning chemotherapy.