Sangamo Therapeutics, Inc. (Nasdaq: SGMO), a genomic medicine company, announced the outcome of a recent successful interaction with the U.S. FDA, providing a clear regulatory pathway to Accelerated Approval for isaralgagene civaparvovec, or ST-920, its wholly owned gene therapy product candidate for the treatment of Fabry disease.

The FDA has agreed in a Type B interaction that data from the ongoing Phase 1/2 STAAR study can serve as the primary basis for approval under the Accelerated Approval Program, using eGFR slope at 52 weeks across all patients as an intermediate clinical endpoint. The complete dataset to support an Accelerated Approval pathway will be available in the first half of 2025. This approach unlocks a potential BLA submission in the second half of 2025, three years ahead of previous estimates, and avoids the requirement for an additional registrational study to establish clinical efficacy.

Sangamo engaged with the FDA on alternative pathways to potential approval following analysis of clinical data from the Phase 1/2 STAAR study showing encouraging safety and efficacy data, including promising preliminary evidence of improved kidney function. Renal manifestations, such as proteinuria or a decreased glomerular filtration rate, occur early in life in almost all male, and in many female, patients with Fabry disease, and can lead to end-stage renal disease and early death. In the 18 male and female patients treated with isaralgagene civaparvovec with more than one year of follow-up data, statistically significant improvements were observed in both mean and median eGFR levels, resulting in a positive annualized eGFR slope. Based on these latest data, the FDA agreed that eGFR slope at 52 weeks can serve as an intermediate clinical endpoint to support a potential Accelerated Approval. The FDA also advised that eGFR slope at 104 weeks may be assessed to verify clinical benefit.

“Fabry is a debilitating disease, for which there is a serious unmet medical need,” said Sandy Macrae, Chief Executive Officer of Sangamo. “I strongly believe in the potential for ST-920 to alleviate many manifestations of Fabry disease and am delighted to have a clear regulatory pathway that could bring this treatment to patients significantly sooner than originally anticipated”.

Dosing was completed in the Phase 1/2 STAAR study in April 2024, with a total of 33 patients dosed. The longest treated patient recently achieved four years of follow-up. The 18th and final patient who started the study on Enzyme Replacement Therapy (ERT) was successfully withdrawn from ERT in September 2024, and all 18 patients remain off ERT as of today. The 52-week eGFR slope data from all enrolled patients in the Phase 1/2 STAAR study will be available in the first half of 2025. A potential BLA submission is anticipated in the second half of 2025.

Sangamo has begun to execute BLA readiness activities for isaralgagene civaparvovec, while continuing to advance ongoing business development discussions with potential collaboration partners.