Ultragenyx Wins FDA Approval for $3.95M Therapy, First for Sanfilippo Syndrome

The U.S. Food and Drug Administration (FDA) granted full approval to Ultragenyx Pharmaceutical's gene therapy, FAYUVI (UX111). This one-time intravenous treatment targets pediatric patients with Sanfilippo syndrome type A (MPS IIIA). It is the first approved therapy to address the underlying cause of this neurodegenerative disease. Previous care for the condition was limited to symptom management.

Ultragenyx set the U.S. price for the treatment at $3.95 million. The approval follows a successful refiling after a 2025 rejection related to manufacturing processes. This milestone validates the company's gene therapy platform and provides a significant new commercial product.

The decision de-risks the company’s outlook and may influence investor sentiment across the rare disease sector. The news impacts gene therapy-focused ETFs, including ARKG and XBI.