TLDR
- The FDA approved Ultragenyx’s Fayuvi, the first-ever treatment targeting the root cause of Sanfilippo syndrome Type A
- Ultragenyx (RARE) stock closed up 13% to $14.50 on Thursday following the announcement
- Fayuvi is a one-time gene therapy administered through a single infusion, using a modified virus to reach the brain
- Clinical trial data showed children who received the therapy scored 23.5 points higher on cognitive tests than untreated patients
- This is Ultragenyx’s second gene therapy approval and sixth FDA approval overall
Ultragenyx (RARE) stock closed up 13% to $14.50 on Thursday after the FDA approved Fayuvi, a gene therapy for Sanfilippo syndrome Type A, a rare inherited disease that progressively destroys the brain and nervous system in children.
Ultragenyx Pharmaceutical Inc., RARE
Before this approval, there was no treatment available that could address the root cause of the disease. Doctors could only manage individual symptoms.
Fayuvi works by correcting a sulfamidase enzyme deficiency. Without this enzyme, a complex sugar molecule called heparan sulfate builds up in the brain, causing progressive cell damage and neurodegeneration.
The therapy is given just once, through a standard infusion into the bloodstream. It uses AAV9, a harmless modified virus, to cross from the blood into the brain and central nervous system.
The FDA based its approval on up to eight years of clinical trial data. Children who received Fayuvi scored 23.5 points higher on cognitive tests compared to untreated patients.
Researchers also tracked heparan sulfate levels directly in brain fluid. The therapy continuously cleared the toxic buildup over time in treated patients.
FDA Approval and Availability
Fayuvi will only be available at Qualified Treatment Centers, which are specialized hospitals trained to administer gene therapies. Ultragenyx plans to launch a website within days listing authorized locations.
The company expects to ship Fayuvi to those centers within 30 to 60 days. Ultragenyx estimates around 3,000 to 5,000 children in accessible regions are living with Sanfilippo syndrome Type A.
The average life expectancy for untreated patients is around 15 years. That number underscores just how much this approval matters for affected families.
Manufacturing and Scale
Fayuvi is manufactured at two specialized facilities, one in Massachusetts and one in Ohio. The dual-site setup is intended to support consistent supply of the therapy going forward.
This approval marks Ultragenyx’s second gene therapy to reach patients and its sixth FDA approval overall. The company has been building out its rare disease pipeline over several years.
The FDA granted the approval based on its review of the clinical data, with scientists tracking both cognitive performance and biological markers in trial participants.
Ultragenyx did not immediately announce a price for Fayuvi, though gene therapies in this class have historically carried high list prices due to their one-time administration and manufacturing complexity.
The therapy became available for ordering through Qualified Treatment Centers following the approval announcement on Thursday.
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