Sangamo’s AAV Gene Therapy Shows Promising Kidney & Clinical Benefits for Fabry Disease

Sangamo Therapeutics (Nasdaq: SGMO) today announced positive topline results from its registrational Phase 1/2 STAAR study for isaralgagene civaparvovec (ST-920), a wholly-owned investigational AAV-based gene therapy for adults with Fabry disease.

AAV Gene Therapy Shows Kidney Function Improvement

Following a single dose of this AAV gene therapy, patients demonstrated a positive mean annualized eGFR slope of 1.965 mL/min/1.73m^2/year at 52 weeks. This crucial kidney function endpoint, agreed upon by the FDA for the Accelerated Approval pathway, supports ST-920’s potential. For patients reaching 104 weeks, the AAV therapy sustained a mean annualized eGFR slope of 1.747 mL/min/1.73m$^2$/year. These results compare favorably to other approved Fabry disease treatments, which show negative eGFR slopes.

“These compelling topline STAAR study results demonstrate the potential for a single dose of ST-920, our AAV-based gene therapy, to provide meaningful clinical benefits above current standards of care,” said Nathalie Dubois-Stringfellow, Ph.D., Chief Development Officer at Sangamo.

Additional Benefits and Favorable AAV Safety Profile

The AAV gene therapy also enabled all 18 patients on enzyme replacement therapy (ERT) to successfully withdraw from it, maintaining stable plasma lyso-Gb3 levels. Elevated alpha-galactosidase A (α-Gal A) activity was maintained for up to 4.5 years, showcasing the potential durability of the AAV treatment. Patients also experienced significant improvements in quality of life scores and other clinical benefits, such as reduced pain medication usage.

Isaralgagene civaparvovec, an AAV-delivered gene therapy, exhibited a favorable safety and tolerability profile without the need for preconditioning. The majority of adverse events were mild (Grade 1-2) and resolved with clinical management, with no study discontinuations due to safety concerns.

Next Steps for the AAV Gene Therapy

Sangamo believes these data support ST-920 as a one-time, durable treatment for Fabry disease and plans an anticipated Biologics License Application (BLA) submission as early as the first quarter of 2026 under the Accelerated Approval pathway. This promising AAV gene therapy has received multiple expedited designations from regulatory bodies, including Orphan Drug, Fast Track, and RMAT from the FDA.