Ultragenyx Announces FDA Acceptance and Priority Review of the Biologics License Application (BLA) for UX111 AAV Gene Therapy to Treat Sanfilippo Syndrome Type A (MPS IIIA)

Core Insights - The FDA has accepted Ultragenyx Pharmaceutical Inc.'s Biologics License Application (BLA) for UX111, a gene therapy for Sanfilippo syndrome type A, with a Priority Review status and a PDUFA action date of August 18, 2025 [1][2] - The acceptance of the BLA is a significant step towards providing the first-ever treatment for Sanfilippo syndrome type A, with the company prepared to launch the therapy upon successful approval [2] - UX111 is a novel in vivo gene therapy designed to address the underlying SGSH enzyme deficiency, which leads to the accumulation of heparan sulfate in the brain, causing neurodegeneration [3][4] Company Overview - Ultragenyx is a biopharmaceutical company focused on developing therapies for serious rare and ultrarare genetic diseases, with a diverse portfolio aimed at addressing high unmet medical needs [5] - The company has a management team experienced in the development and commercialization of rare disease therapeutics, emphasizing efficient drug development processes [6] Product Details - UX111 is currently in Phase 1/2/3 development and is administered as a one-time intravenous infusion using a self-complementary AAV9 vector to deliver a functional SGSH gene [3] - The therapy has received multiple designations, including Regenerative Medicine Advanced Therapy and Orphan Drug designations in the U.S., and PRIME designation in the EU [3] Disease Context - Sanfilippo syndrome type A is a rare, fatal lysosomal storage disease affecting approximately 3,000 to 5,000 patients, characterized by rapid neurodegeneration and a median life expectancy of 15 years [4] - The disease is caused by biallelic pathogenic variants in the SGSH gene, leading to a deficiency in the SGSH enzyme responsible for breaking down heparan sulfate [4]