SANGAMO THERAPEUTICS, INC 8-K

What Happened

• Sangamo Therapeutics announced clinical results from its registrational Phase 1/2 STAAR study of isaralgagene civaparvovec (ST-920) for Fabry disease and presented data at the 22nd WORLDSymposium (Feb 2–6, 2026). The company reported results based on a data cutoff of April 10, 2025, when 33 patients had been dosed (32 with ≥52 weeks follow-up).
• The U.S. FDA agreed (Type B meeting, Oct 2025) that data from the ongoing Phase 1/2 STAAR study can serve as the primary basis for approval under the Accelerated Approval program using mean annualized eGFR slope at 52 weeks as an intermediate clinical endpoint. Sangamo initiated a rolling Biologics License Application (BLA) submission to the FDA in December 2025.
• Key efficacy/safety highlights: positive mean annualized eGFR slopes at 52 weeks (1.965 mL/min/1.73m2/yr; 95% CI: -0.153, 4.083) and by a mixed model (RIRS) 2.020 (95% CI: -0.055, 4.095) across 32 patients; Week 104 slopes remained positive in the subset with longer follow-up. ST-920 was generally well tolerated — most adverse events were Grade 1–2; four treatment-emergent serious AEs occurred (one SAE judged related to treatment). No deaths, no TMA or complement activation events reported.

Key Details

• 33 patients dosed as of Apr 10, 2025 (ages 18–67); 32 patients reached ≥52 weeks follow-up; median follow-up 24 months; first patient >54 months.
• FDA accepted use of 52-week mean annualized eGFR slope from the STAAR study as an intermediate endpoint for Accelerated Approval; rolling BLA began Dec 2025.
• 52-week mean annualized eGFR slope: 1.965 mL/min/1.73m2/yr (95% CI: -0.153, 4.083); RIRS estimate 2.020 (95% CI: -0.055, 4.095). Week 104 slopes in 19 patients remained positive. Historical conservative comparator UCL = -1.055 mL/min/1.73m2/yr.
• All 18 patients entering the study on enzyme replacement therapy (ERT) were able to withdraw from ERT after dosing; 15 ERT‑naïve/pseudo‑naïve patients showed sustained normal to supraphysiological α‑Gal A activity (up to 54 months in some patients). Immunogenicity to α‑Gal A decreased or became undetectable in most previously antibody‑positive patients.

Why It Matters

• For investors, the combination of positive registrational Phase 1/2 data, FDA agreement on an Accelerated Approval pathway using a 52‑week eGFR slope endpoint, and a rolling BLA submission are materially important steps toward potential regulatory approval and commercialization of ST-920 for Fabry disease.
• The safety profile reported so far is generally favorable (mostly mild/moderate AEs and no deaths), and efficacy signals include durable enzyme expression, biomarker improvements (lyso‑Gb3), QoL gains, and positive eGFR slope estimates — all items FDA will weigh in review and confirmatory requirements.
• Remaining material considerations noted in the filing include the need for confirmatory data (e.g., durability/verification at later timepoints such as 104 weeks), the usual regulatory and clinical risks, and Sangamo’s need for additional funding to advance and commercialize product candidates.