FDA Approves First Gene Therapy for Sanfilippo Syndrome Type A at $3.95 Million
On September 17, 2026, the FDA approved Fayuvi, a one-time gene therapy from Ultragenyx, as the first treatment designed to alter the course of Sanfilippo syndrome type A in pediatric patients who previously had no options beyond symptom management. Clinical evidence supporting approval came from 17 patients in an open-label, single-arm study compared against an external natural-history cohort, not a randomized controlled trial. The therapy carries a U.S. list price of $3.95 million and comes with postmarketing requirements including a companion diagnostic study due by 2029.