FDA Approves Ultragenyx's Fayuvi, First Gene Therapy for Sanfilippo Syndrome

The U.S. Food and Drug Administration (FDA) on Thursday approved Ultragenyx Pharmaceutical's gene therapy, Fayuvi, establishing the first approved treatment for the rare and fatal childhood disorder Sanfilippo syndrome Type A. Following the landmark decision, shares of Ultragenyx (NASDAQ: RARE) climbed over 10% in afternoon trading.

A Groundbreaking Treatment

Fayuvi is approved for pediatric patients with Sanfilippo syndrome Type A, an inherited condition that causes progressive and severe damage to the brain and nervous system. The disease stems from a deficiency of an enzyme called sulfamidase, which leads to a toxic accumulation of a complex sugar, heparan sulfate, in the body's cells.

Administered as a single intravenous infusion, the gene therapy works by delivering a functional copy of the SGSH gene to the patient's cells. This enables the body to produce the missing sulfamidase enzyme, thereby breaking down the harmful buildup that causes children to lose cognitive, speech, and motor functions over time.

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Clinical Efficacy and Outlook

The FDA's approval was supported by clinical trial data showing that children treated with the therapy either maintained or improved their cognitive function when compared to untreated patients. Glenn O’Neill, president and co-founder of the Cure Sanfilippo Foundation, called the approval a "real life-changing chance" for children with the disease.

Ultragenyx announced that it expects Fayuvi to become available at specialized treatment centers across the United States within 30 to 60 days. The approval marks a significant milestone in gene therapy, offering a new treatment paradigm for a disease that previously had no approved therapeutic options.