FDA assigns PDUFA target action date of November 9, 2025
RGX-121 on track to be the first gene therapy and one-time treatment for MPS II
Partner Nippon Shinyaku to lead commercialization upon potential approval
REGENXBIO to lead commercial manufacturing and supply chain
ROCKVILLE, Md., May 13, 2025 /PRNewswire/ -- REGENXBIO Inc. (Nasdaq: RGNX) today announced the U.S. Food and Drug Administration (FDA) has accepted for review the Biologics License Application (BLA) seeking accelerated approval for clemidsogene lanparvovec (RGX-121) for the treatment of Mucopolysaccharidosis II (MPS II), also known as Hunter syndrome.
The FDA granted the BLA Priority Review with a Prescription Drug User Fee Act (PDUFA) target action date of November 9, 2025.
"Acceptance of the RGX-121 BLA marks an exciting milestone on our path to bring the MPS II patient community a one-time treatment with the potential to address both the neurodevelopmental and systemic effects of Hunter syndrome," said Curran M. Simpson, President and Chief Executive Officer of REGENXBIO. "Supported by positive biomarker data and long-term outcomes, RGX-121 has the potential to be a first-in-class gene therapy that could dramatically transform the MPS II treatment landscape and reduce the significant burden patients and families currently face with weekly enzyme replacement therapy."
RGX-121 has received Orphan Drug Product, Rare Pediatric Disease, Fast Track and Regenerative Medicine Advanced Therapy (RMAT) designations from the U.S. Food and Drug Administration and advanced therapy medicinal products (ATMP) classification from the European Medicines Agency.
Under the strategic partnership announced in January 2025, following potential FDA approval, RGX-121 will be commercialized by NS Pharma, Inc., a wholly-owned subsidiary of Nippon Shinyaku, in the U.S. Approval of RGX-121 could result in receipt of a Priority Review Voucher (PRV). REGENXBIO retains all rights to, and 100 percent of any proceeds related to the potential sale of, the PRV for RGX-121.
About RGX-121 (clemidsogene lanparvovec) RGX-121 is a potential one-time AAV therapeutic for the treatment of boys with MPS II, designed to deliver the iduronate-2-sulfatase (IDS) gene to the central nervous system (CNS). Delivery of the IDS gene within cells in the CNS could provide a permanent source of secreted iduronate-2-sulfatase (I2S) protein beyond the blood-brain barrier, allowing for long-term cross correction of cells throughout the CNS. RGX-121 expressed protein is structurally identical to normal I2S.
About Mucopolysaccharidosis Type II (MPS II) MPS II, or Hunter Syndrome, is a rare, X-linked recessive disease caused by a deficiency in the lysosomal enzyme I2S leading to an accumulation of glycosaminoglycans (GAGs), including heparan sulfate (HS) in tissues which ultimately results in cell, tissue, and organ dysfunction, including in the CNS. In severe forms of the disease, early developmental milestones may be met, but developmental delay is readily apparent by 18 to 24 months. Specific treatment to address the neurological manifestations of MPS II remains a significant unmet medical need. Key biomarkers of I2S enzymatic activity in MPS II patients include its substrate heparan sulfate (HS) D2S6, which has been shown to correlate with neurocognitive manifestations of the disorder.
ABOUT REGENXBIO Inc. REGENXBIO is a biotechnology company on a mission to improve lives through the curative potential of gene therapy. Since its founding in 2009, REGENXBIO has pioneered the field of AAV gene therapy. REGENXBIO is advancing a late-stage pipeline of one-time treatments for rare and retinal diseases, including RGX-202 for the treatment of Duchenne; clemidsogene lanparvovec (RGX-121) for the treatment of MPS II and RGX-111 for the treatment of MPS I, both in partnership with Nippon Shinyaku; and surabgene lomparvovec (ABBV-RGX-314) for the treatment of wet AMD and diabetic retinopathy, in collaboration with AbbVie. Thousands of patients have been treated with REGENXBIO's AAV platform, including those receiving Novartis' ZOLGENSMA®. REGENXBIO's investigational gene therapies have the potential to change the way healthcare is delivered for millions of people. For more information, please visit www.REGENXBIO.com.
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