Ultragenyx Pharmaceutical received FDA approval on 17 September for Fayuvi, the first treatment for neurologic manifestations of Sanfilippo syndrome Type A in paediatric patients. The stock jumped over 12% on the news but remains down nearly 40% for the year. The approval strengthens Ultragenyx's 2027 profitability target. The company posted a $575 million loss on $673 million revenue in 2025 and projects $730 million to $760 million in 2026 revenue from current products, excluding new launches. Fayuvi carries a $3.95 million list price for one-time treatment. JP Morgan estimates peak global sales of $200 million to $250 million, representing roughly 26% of Ultragenyx's 2026 revenue guidance at the lower end. The drug will become available to patients within 30 to 60 days. Hedge fund holdings fell to 50 in Q2 from 55 in Q1, though AQR Capital Management increased its stake 44% to 6.6 million shares.

The US Food and Drug Administration has approved Ultragenyx's Fayuvi gene therapy for paediatric patients with Sanfilippo syndrome Type A, a rare inherited condition that progressively damages the brain and nervous system. The company has priced the one-time treatment at $3.95 million. The disease causes children to gradually lose cognitive, speech and motor skills due to toxic accumulation of complex sugars in the body and brain. Administered as a single intravenous infusion, Fayuvi delivers a functional gene copy enabling the body to produce the missing enzyme. Ultragenyx said lifetime care costs for affected children can exceed $8 million. J.P. Morgan analysts estimate the therapy could reach peak worldwide sales of $200 million to $250 million. The treatment will be available at specialised US centres within 30 to 60 days.

Ultragenyx Pharmaceutical has received FDA approval for FAYUVI, the first-ever treatment for Sanfilippo syndrome Type A, a progressive and fatal neurodegenerative disease. The gene therapy, also known as UX111, is approved for pediatric patients with the condition. FAYUVI represents Ultragenyx's second gene therapy approval and sixth FDA approval overall. The company received a Priority Review Voucher with the approval. The commercial product is expected to be available to ship to Qualified Treatment Centers within 30 to 60 days. Ultragenyx's UltraCare programme will support access to the treatment. The approval follows decades of research, advocacy and collaboration across the Sanfilippo community, patient organisations and industry partners. The company aims to bring the treatment to patients globally.