FDA Delays Regenxbio Hunter Syndrome Gene Therapy Decision to February 2026

The U.S. Food and Drug Administration has pushed back its target action date for Regenxbio’s biologics license application for clemidsogene lanparvovec (RGX-121), a one-time gene therapy for Hunter syndrome, by three months. The Prescription Drug User Fee Act (PDUFA) deadline moves to Feb. 8, 2026 from Nov. 9, 2025. The agency requested and is now reviewing 12-month follow-up data from all 13 patients enrolled in the CAMPSIITE pivotal study. Regenxbio said the FDA’s initial review raised no safety concerns and that recent pre-license and bioresearch monitoring inspections resulted in no observations. Earlier trial results showed the therapy cut the cerebrospinal-fluid biomarker D2S6 by a median 86% and enabled 80% of treated patients to discontinue standard enzyme replacement therapy. Regenxbio, which holds orphan drug, rare pediatric disease, fast-track and RMAT designations for RGX-121, said commercial launch preparations remain on schedule despite the delay.