PTC Therapeutics said it was selected as the winning bidder in a competitive bankruptcy auction to acquire ST-920 from Sangamo Therapeutics, expanding its rare disease portfolio with a BLA-stage gene therapy for Fabry disease. The transaction includes $111 million upfront and up to $100 million in contingent milestone payments tied to certain regulatory approvals, and is expected to close in late Q3 or early Q4 2026, subject to definitive documentation, bankruptcy court approval, antitrust review and other customary conditions. ST-920, also known as isaralgagene civaparvovec, is a one-time administered AAV gene therapy designed to restore long-term production of the deficient alpha-galactosidase A enzyme in Fabry disease. PTC expects the rolling biologics license application, or BLA, to the FDA for accelerated approval to be completed in Q4 2026, with potential commercial launch in 2027. The filing is based on 52-week data from the Phase 1/2 STAAR study, including favorable renal function results, along with safety and tolerability data. The company said the therapy showed a positive mean annualized estimated glomerular filtration rate, or eGFR, slope at 52 weeks, alongside evidence of benefit in cardiac function and quality of life. It also said all participants who were on enzyme replacement therapy at the start of the study were withdrawn from that treatment, and that increased enzyme activity has been maintained for up to 4.5 years in the earliest treated participant. PTC said ST-920 has received RMAT, Orphan Drug and Fast Track designations from the FDA, and that it also plans to pursue approvals outside the United States using its existing rare disease commercial and regulatory infrastructure.