One-time treatment provides a new option for pediatric patients with a rare, progressive genetic disorder

As announced in a recent press release, the U.S. Food and Drug Administration has approved Fayuvi (rebisufligene etisparvovec-hopf) for pediatric patients with mucopolysaccharidosis type IIIA (MPS IIIA), also known as Sanfilippo syndrome type A. It is the first FDA-approved treatment intended to address the underlying cause of this disease.

MPS IIIA is a rare inherited disorder that progressively affects the brain and nervous system. Children may initially develop typically, but over time they can lose cognitive, language and other developmental skills. Before this approval, care focused primarily on managing symptoms.

Fayuvi is administered once through an intravenous infusion. The therapy uses a modified, non-infectious virus known as AAV9 to deliver a working copy of the SGSH gene to the body’s cells. The gene helps cells produce sulfamidase, an enzyme that is missing or deficient in people with MPS IIIA. This enzyme helps break down heparan sulfate, a substance that otherwise accumulates in cells, including cells in the brain.

The FDA evaluated Fayuvi in an open-label, single-arm, multicenter clinical study involving children with MPS IIIA. The study included patients between 2 and 5 years of age and assessed changes in cognitive development. Compared with an untreated historical group, children who received Fayuvi generally maintained or improved their cognitive function during a period when children with MPS IIIA would typically be expected to plateau or decline.

“Today’s approval offers families affected by Sanfilippo syndrome type A a new treatment option for a serious disease that previously had no FDA-approved therapy aimed at changing its course,” said Acting FDA Commissioner Kyle Diamantas, J.D. “This decision also reflects the potential of gene therapy to address rare diseases with significant unmet medical needs.”

The safety of Fayuvi was studied in children who received a single intravenous infusion across clinical studies. The most frequently reported side effects, occurring in more than 5% of patients, included elevated liver enzymes, nausea, vomiting, fever, reduced appetite, lower white blood cell and platelet counts, and increased amylase levels.

Healthcare professionals should review the full prescribing information, including warnings, precautions, and monitoring requirements, before administering.