FDA Grants Standard Full Approval to Ultragenyx FAYUVI (Rebisufligene Etisparvovec-Hopf), the First Approved Treatment for Sanfilippo Syndrome Type A
Ultragenyx Pharmaceutical announced on Thursday, September 17, 2026 that the FDA granted standard full approval to FAYUVI (rebisufligene etisparvovec-hopf), a single-dose intravenous AAV9 gene therapy, for the neurologic manifestations of mucopolysaccharidosis type IIIA (MPS IIIA, Sanfilippo syndrome type A) in pediatric patients with preserved neurodevelopmental function. The company calls it the first FDA-approved treatment for Sanfilippo syndrome type A and its second gene therapy approval. Treated children (n=17) had a 23.5-point higher cognitive score than natural-history controls (n=27), with follow-up of up to nearly 8 years and reduced cerebrospinal fluid heparan sulfate. Ultragenyx received a priority review voucher, expects to ship within 30 to 60 days, and makes FAYUVI in Bedford, Massachusetts and at Andelyn Biosciences in Columbus, Ohio. BioSpace reported a $3.95 million wholesale acquisition cost, an initial FDA rejection in July 2025 over manufacturing issues, and a 13% share gain on the day.