The U.S. Food and Drug Administration (FDA) has approved Fayuvi (rebisufligene etisparvovec-hopf), marking the first FDA-approved treatment for pediatric patients with mucopolysaccharidosis type IIIA (MPS IIIA), also known as Sanfilippo syndrome type A.
MPS IIIA is a rare inherited disease that progressively damages the brain and nervous system, causing children to lose cognitive, language, and other developmental abilities over time. Until this approval, treatment options were limited to managing symptoms, with no therapy designed to alter the underlying course of the disease.
Fayuvi is a one-time, intravenous gene therapy. It utilizes a modified, non-infectious adeno-associated virus serotype 9 (AAV9) to deliver a working copy of the SGSH gene into a patient’s cells. This enables the body to produce sulfamidase, the enzyme deficient in MPS IIIA, allowing heparan sulfate to be properly broken down and reducing its harmful buildup.
The safety and effectiveness of Fayuvi were evaluated in an open-label, single-arm, multicenter clinical study. The study focused on pediatric patients aged 2 to 5 years, measuring mean changes in cognitive scores. The results indicated that Fayuvi-treated patients maintained or improved cognitive function compared to an untreated historical control cohort.
The FDA granted Fayuvi Orphan Drug, Fast Track, and Breakthrough Therapy designations. The approval was granted to Ultragenyx Pharmaceutical, Inc.
Common adverse reactions reported in more than 5% of patients included increases in liver enzymes (AST), nausea, vomiting, fever, decreased appetite, decreased white blood cell and platelet counts, and increased amylase. Important safety warnings include the risk of thrombotic microangiopathy (TMA) and the potential long-term risk that the inserted genetic material could integrate into the genome, potentially leading to tumor development.
Administration of Fayuvi occurs in a healthcare setting equipped to manage infusion reactions. All patients receive corticosteroid treatment beginning one day before the infusion and continuing for a minimum of eight weeks afterward.
