FAYUVI (rebisufligene etisparvovec-hopf; UX111)
Sanfilippo syndrome type A (mucopolysaccharidosis type IIIA) · Pediatric patients with Sanfilippo syndrome type A
RARE · Ultragenyx Pharmaceutical
Regulatory designations
Full timeline
4 milestonesFDA granted full approval to FAYUVI
FDA granted standard full approval to FAYUVI, the first FDA-approved treatment for pediatric patients with mucopolysaccharidosis type IIIA (Sanfilippo syndrome type A). Ultragenyx received a Priority Review Voucher with the approval.
FDA — Approval of FAYUVI for pediatric Sanfilippo syndrome type A↗FDA accepted the BLA resubmission
FDA accepted the resubmitted UX111 BLA for review after Ultragenyx added information addressing the prior manufacturing-related observations.
Ultragenyx — BLA resubmission acceptance↗FDA issued a Complete Response Letter in the first review cycle
The CRL cited chemistry, manufacturing and controls observations; Ultragenyx said FDA acknowledged the clinical data as robust and the biomarker evidence as supportive.
Ultragenyx — UX111 Complete Response Letter↗Ultragenyx submitted the original BLA
Ultragenyx submitted the original BLA seeking accelerated approval, supported by data from the ongoing Transpher A study.
Ultragenyx — 2024 results and UX111 regulatory update↗Related News
Ultragenyx Enters into Agreement to Sell Rare Pediatric Disease Priority Review Voucher for $210 Million
Oct 2, 2026Ultragenyx Announces Marketing Authorisation Application (MAA) Submission to the European Medicines Agency (EMA) for the First Investigational Gene Therapy for MPS IIIA (Sanfilippo Syndrome Type A)
Sep 17, 2026Ultragenyx Announces Approval of FAYUVI™ Gene Therapy, the First-Ever FDA-Approved Treatment for Sanfilippo Syndrome Type A (MPS IIIA)
Sep 2, 2026Ultragenyx Announces Phase 3 Aspire results in Angelman Syndrome
Sep 1, 2026Ultragenyx Announces the Publication of a Successful 96-Week Randomized, Placebo-Controlled Trial with Crossover Treatment of GENGLYCOS™ (also known as DTX401) AAV Gene Therapy in GSDIa in The Journal of Inherited Metabolic Disease