Ultragenyx receives FDA approval for Fayuvi, first therapy for Sanfilippo syndrome type A, priced at $3.95 M

The FDA has approved Ultragenyx's gene therapy rebisufligene etisparvovec, to be sold under the brand name Fayuvi, for the treatment of Sanfilippo syndrome type A, an ultra-rare progressive neurological disease in children.

This is the first FDA‑approved therapy for the fatal condition and is indicated for patients who still have preserved neurodevelopmental function.

The approval follows a prior rejection in July 2025 due to manufacturing issues and arrives shortly after the company secured approval for another gene therapy last month.

Ultragenyx expects to begin shipping Fayuvi within 30 to 60 days, with a wholesale acquisition cost of $3.95 million, placing it among the most expensive gene therapies on the market.

The announcement lifted Ultragenyx's share price, which closed up 13% on the day of the news.