Regenxbio announces FDA review extension for RGX-121 BLA

Regenxbio (RGNX) announced that the U.S. Food and Drug Administration extended its review timeline of the Biologics License Application for clemidsogene lanparvovec for the treatment of Mucopolysaccharidosis II, also known as Hunter syndrome. The Prescription Drug User Fee Act goal date has been extended from November 9, 2025 to February 8, 2026. The extension follows the company’s submission of longer-term clinical data for all patients in the pivotal study of RGX-121 in response to an FDA information request. These positive 12-month clinical data are consistent with biomarker and neurodevelopmental data previously submitted on the same patients in the BLA and will be presented during the International Congress of Inborn Errors of Metabolism in September 2025. In August 2025, the FDA completed a pre-license inspection and bioresearch monitoring information inspection for the RGX-121 BLA with no observations. No safety-related concerns have been raised by the FDA during the BLA review. “Boys with this rare, devastating disease have no treatment options to address neurodevelopmental decline, and the Hunter syndrome community is in urgent need for a therapeutic option with the potential to improve these patients’ lives,” said Curran M. Simpson, President and Chief Executive Officer of REGENXBIO. “We promptly provided the FDA with the information requested and expect the commercial launch plans remain on track.”