The FDA has approved Fayuvi (rebisufligene etisparvovec-hopf), the first disease-modifying gene therapy for pediatric Sanfilippo syndrome type A (MPS IIIA), signaling a major milestone in treating this fatal, progressive disease.

Ultragenyx shares jumped about 12% on the news, reflecting investor optimism about the therapy and its potential impact.

Ultragenyx expects Fayuvi to be available at specialized U.S. treatment centers within 30 to 60 days after approval, with Andelyn Biosciences manufacturing supply at its Columbus, Ohio facility and Ultragenyx’s Bedford, Massachusetts facility.

The report notes that the piece is not financial advice and points readers to additional resources for valuation and future projections.

Patient advocacy groups underscore the therapy’s potential to change prognosis and offer families a concrete treatment plan where none existed before.

Andelyn’s AAV Curator Platform is highlighted as the backbone for commercial-scale manufacturing of Fayuvi.

Safety profiles show common adverse events such as elevated liver enzymes, nausea, vomiting, fever, reduced appetite, and hematologic changes, with risks including thrombotic microangiopathy and potential long-term tumor development due to vector integration.

Clinical data indicate the therapy may halt or slow disease progression, with treated children maintaining or improving cognition compared with historical controls.

Earlier concerns about Ultragenyx’ stock decline over the past five years frame questions about current valuation relative to sales potential and pipeline.

Label warnings emphasize long-term safety monitoring due to potential genome integration and cancer risk, and note infusion-related reactions and steroid needs during treatment.

In trials, treated patients showed durable cognitive benefits, diverging from the natural course of the disease compared with untreated groups.

Market estimates place the per-patient price around $3.95 million, with commercial coverage and patient navigation support provided through Ultragenyx UltraCare.