The US Food and Drug Administration has approved a new gene therapy for a rare neurological disorder that manifests at an early age – Sanfilippo syndrome type A. Until the approval, treatment was limited to managing symptoms. The therapy, Fayuvi (rebisufligene etisparvovec), is an adeno-associated serotype 9 virus therapy (AAV9) that delivers a working copy of a gene enabling the body to produce sulfamidase, an enzyme which is missing in patients with the disease. Children with deficient supplies of the enzyme cannot beak down a sugar chain known as heparan sulfate. These are molecules found in different parts of cells, and their abnormal build up can damage the central nervous system and other organs.
Fayuvi is intended as a one-time gene therapy that delivers a working copy of the sulfoglucosamine sulfohydrolase (SGSH) gene to a patient’s cells. The impact of the therapy was tested in a single-arm, multicentre clinical study in paediatric patients with the disorder. The study measured mean changes in cognitive scores of patients between the ages of two and five years. Those who received the treatment improved cognitive function compared with an untreated historical control cohort. According to the FDA, this was a meaningful divergence from the expected natural course of the disease during a critical period of the patients’ development.
“Achieving meaningful neurodevelopmental benefit through a single intravenous administration represents a significant scientific milestone – demonstrating that systemic AAV9-mediated gene delivery can reach the central nervous system at therapeutically relevant levels in paediatric patients,” said Megha Kaushal, acting deputy director of the FDA’s Office of Therapeutic Products, in a prepared statement on 17 September. The agency issued a marketing authorisation for the therapy to Ultragenyx Pharmaceutical Inc of the US.
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