Regenxbio Extends FDA Review Timeline for RGX-121

By Hao Liu • Tuesday, August 19 06:03 • Permanent Link

Regenxbio Inc. (NASDAQ: RGNX) has announced an extension in the review timeline of the biologics license application (BLA) for clemidsogene lanparvovec (RGX-121) by the U.S. Food and Drug Administration (FDA). The Prescription Drug User Fee Act (PDUFA) goal date has been extended from November 9, 2025, to February 8, 2026. This 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.

The extension is based on positive 12-month clinical data for all patients (n=13) in the pivotal study of RGX-121, which are consistent with biomarker and neurodevelopmental data previously submitted. These data will be presented during the International Congress of Inborn Errors of Metabolism (ICIEM) in September 2025. Additionally, in August 2025, the FDA completed a pre-license inspection and bioresearch monitoring information inspection for the RGX-121 BLA with no observations. There have been no safety-related concerns raised by the FDA during the BLA review.

RGX-121, if approved, would be the first and only potential one-time commercially-available therapy designed to directly address the underlying genetic cause of Hunter syndrome, also known as mucopolysaccharidosis II (MPS II). The treatment aims to deliver the iduronate-2-sulfatase (IDS) gene to the central nervous system (CNS) and provide a permanent source of secreted IDS protein beyond the blood-brain barrier, allowing for long-term cross correction of cells throughout the CNS.

Regenxbio is focused on advancing a late-stage pipeline of one-time treatments for rare and retinal diseases, including RGX-202 for the treatment of Duchenne muscular dystrophy, RGX-121 for the treatment of MPS II, and RGX-111 for the treatment of MPS I. The company's investigational gene therapies have the potential to change the way healthcare is delivered for millions of people. Following these announcements, the company's shares moved -0.51%, and are now trading at a price of $8.775. For more information, read the company's full 8-K submission here.

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