Sangamo Therapeutics’ investigational gene therapy appears to improve kidney function at 52 weeks for patients with a rare genetic disorder.
The biotech plans to use the data for an FDA submission next year via the agency's accelerated approval pathway.
The topline results come from a registrational phase 1/2 trial, dubbed STAAR, and include data from 32 patients with Fabry disease, a rare lysosomal storage disorder.
The open-label study is evaluating a one-time infusion of isaralgagene civaparvovec, also known as ST-920. Some patients were on enzyme replacement therapy (ERT), while others had been off ERT for six or more months and some had never received the therapy.
The trial demonstrated a mean annualized estimated glomerular filtration rate (eGFR) slope of 1.965 mL/min/1.73m2/year at 52 weeks across all dosed patients, according to a June 24 release.
For 19 patients with two years of follow-up, the mean annualized eGFR slope was 1.747 mL/min/1.73m2/year.
The FDA has previously agreed that the measure, a surrogate for renal function over time, can serve as an intermediate clinical endpoint for an accelerated approval submission from Sangamo. In the past, the agency has accepted eGFR slope as a way to measure the rate of decline in kidney function.
Sangamo, for its part, believes the data "support the potential for isaralgagene civaparvovec as a one-time, durable treatment for Fabry disease that can improve patient outcomes," according to the company's press release. In the company's most recent annual report, Sangamo said prior results from the trial showed "notable improvements in renal function" based on the eGFR slope measure.
All 18 patients who started the study on ERT have stopped and remain off the therapy. A stabilization in cardiac endpoints was also recorded, according to the biotech.
The gene therapy, which doesn’t require preconditioning, demonstrated a favorable safety and tolerability profile, according to Sangamo. Most adverse events were mild, and the most common treatment-emergent adverse events were fever and COVID-19. No safety-related study discontinuations were reported.
Next, Sangamo will compare the eGFR slope data against approved Fabry treatments by performing a meta-analysis of published studies. Estimated mean annualized eGFR slopes for Takeda’s Replagal, Sanofi’s Fabrazyme and Amicus Therapeutics’ Galafold range from -2.2 to -0.4 mL/min/1.73m2/year, according to Sangamo.
The California biotech plans on filing a biologics license application as early as the first quarter of 2026, according to the release. Sangamo’s gene therapy has garnered orphan, fast track and regenerative medicine advanced therapy tags from the FDA.
Additional analyses of the full STAAR dataset will be presented at an upcoming medical meeting, the biotech said.
As Sangamo prepares for an FDA submission, the biotech is “continuing to engage in business development negotiations for a potential Fabry commercialization agreement,” according to the release. A partner appears necessary for the cash-strapped company to bring the gene therapy to the finish line.
Sangamo started 2025 with a stock crash driven by Pfizer terminating a hemophilia A gene therapy deal, which eliminated the potential for the biotech to collect up to $220 million in biobucks. The news came on top of Sangamo’s November 2024 announcement that it only had enough money in the bank to last until the first quarter of 2025.
Luckily for Sangamo, Eli Lilly inked an $18 million upfront deal this April to use the biotech's neurotropic adeno-associated virus capsid in hopes of developing a gene therapy for a central nervous system disease. The pact gives Sangamo the chance to earn up to $1.4 billion as the entire gene therapy field faces a deep reckoning.
As of March 31, Sangamo had $25.1 million in cash and cash equivalents, according to a May 12 earnings release. That money, combined with the upfront cash from Lilly, is expected to fund operations into the third quarter of 2025, the biotech said.