PTC Therapeutics to Acquire BLA-Stage ST-920 Fabry Disease Gene Therapy from Sangamo
核心洞察
PTC Therapeutics was selected as the winning bidder to acquire ST-920, a BLA-stage one-time AAV gene therapy for Fabry disease (搜索), from Sangamo Therapeutics in a competitive bankruptcy auction.
The transaction includes $111 million upfront and up to $100 million in contingent milestone payments, with a rolling BLA submission to the FDA expected to be completed in Q4 2026.
The Phase 1/2 STAAR study demonstrated a positive mean annualized eGFR slope at 52 weeks and sustained α-Gal A activity for up to 4.5 years, with no requirement for routine immunosuppressive agents.
PTC Therapeutics, Inc. (NASDAQ: PTCT) announced on Aug. 12, 2026 that it was selected as the winning bidder to acquire ST-920, a BLA-stage one-time administered AAV gene therapy for Fabry disease (搜索), from Sangamo Therapeutics in a competitive bankruptcy auction. The terms include $111 million upfront and up to $100 million in contingent milestone payments based on certain regulatory approvals. A rolling BLA submission to the FDA for accelerated approval of ST-920 is expected to be completed in Q4 2026, with potential for commercial launch in 2027.
"This transaction advances our strategy of leveraging our accomplished existing rare disease global commercial infrastructure to accelerate short- and intermediate-term revenue growth," said Matthew B. Klein, M.D., Chief Executive Officer. "The ST-920 gene therapy program puts another innovative and valuable product in the demonstrated capable hands of our customer-facing teams. This was a unique opportunity with the potential for significant return on investment without the need for any development or commercial build and without impacting our objective of reaching cashflow break even in 2026."
Fabry Disease and the ST-920 Mechanism
Fabry disease (搜索) is a rare, inherited lysosomal storage disorder caused by mutations in the GLA gene (搜索), resulting in deficiency of the alpha-galactosidase A (搜索) (α-Gal A) enzyme and causing a range of serious signs and symptoms that require lifelong treatments. It is estimated that there are 11,000 people living with Fabry disease in the United States, with similar prevalence rates in markets where PTC has the potential to commercialize.
ST-920 is designed as a one-time administered AAV gene therapy that enables long-term production of the deficient α-Gal A enzyme and significant reduction in globotriaosylceramide (Gb3) levels, with demonstrated durable clinical benefit and reduction of the burden associated with chronic Enzyme Replacement Therapy (ERT). ST-920 has received Regenerative Medicine Advanced Therapy (RMAT) designation as well as Orphan Drug and Fast Track designations from the FDA.
Clinical Evidence from the STAAR Study
The Phase 1/2 STAAR study demonstrated positive mean annualized estimated glomerular filtration rate (eGFR) slope at 52 weeks following ST-920 administration, as well as evidence of favorable effect on other aspects of Fabry disease (搜索) including cardiac function and quality of life. The finding of improved eGFR over 52 weeks is differentiated from other Fabry therapies, which demonstrated improved renal function but still negative eGFR slope from baseline. Furthermore, all study participants on ERT at study start were withdrawn from ERT.
Durability of effect has been demonstrated with sustained increased α-Gal A activity maintained for up to 4.5 years for the earliest treated study participant, and evidence of maintained improvements in renal function across the study population. In addition, ST-920 has demonstrated an encouraging safety and tolerability profile, and there is no requirement for routine prophylactic or post-infusion systemic immunosuppressive agents.
The BLA submission for accelerated approval is based on the intermediate clinical endpoint of annualized eGFR at Week 52 as aligned with the FDA, with 104-week results from the STAAR study planned to provide confirmatory evidence to support traditional approval. The nonclinical and clinical BLA modules have already been submitted as part of a rolling submission, with the CMC package expected to be submitted in Q4 2026.
Study Design and Regulatory Status
The Phase 1/2 STAAR study was a global open-label, single-dose, dose-ranging, multicenter clinical study designed to evaluate isaralgagene civaparvovec, or ST-920, in patients with Fabry disease (搜索). Isaralgagene civaparvovec requires a one-time infusion without preconditioning. The study enrolled patients who were on ERT, were ERT pseudo-naïve (defined as having been off ERT for six or more months), or who were ERT-naïve.
The FDA has granted Orphan Drug, Fast Track, and RMAT designations to isaralgagene civaparvovec, which has also received Orphan Medicinal Product designation and PRIME eligibility from the European Medicines Agency and Innovative Licensing and Access Pathway from the U.K. Medicines and Healthcare products Regulatory Agency. PTC will also pursue regulatory approval outside of the United States, again leveraging existing regulatory and commercial rare disease infrastructure.
Transaction Details and Next Steps
The acquisition remains subject to definitive documentation, bankruptcy court approval, antitrust review, and other customary closing conditions. It is expected to close in late Q3 or early Q4 2026. PTC will hold a conference call on Aug. 12, 2026 at 5 p.m. ET to discuss the news.