Ultragenyx Pharmaceutical has announced that the US Food and Drug Administration (FDA) has granted standard full approval of FAYUVI (rebisufligene etisparvovec-hopf), also known as UX111, for the treatment of pediatric patients with mucopolysaccharidosis type IIIA (MPS IIIA, Sanfilippo syndrome Type A).

FAYUVI is the first-ever FDA-approved treatment for Sanfilippo syndrome Type A, a progressive and fatal neurodegenerative disease, and the second gene therapy approval for Ultragenyx. The company received a Priority Review Voucher (PRV) upon this approval.

Emil D Kakkis, MD, PhD, Chief Executive Officer and President, Ultragenyx, said, "The approval of FAYUVI reflects years of research from scientists and developers, as well as unwavering support from so many families and patient organisations in the face of a devastating, universally fatal disease with no treatment options. This is a historic milestone for a community that has waited far too long, but has never given up hope. We recognise the profound urgency of making this therapy available to families, and our focus now is on supporting timely access in the US as we work closely with treatment centers and payers to support families on the gene therapy treatment journey. FDA approval is an important first step toward our long-term goal to bring this treatment option to families of children with Sanfilippo syndrome Type A around the world.”

Sanfilippo syndrome Type A is an ultra-rare, fatal lysosomal storage disease that primarily affects the brain and is marked by rapid, progressive neurodegeneration beginning in early childhood. Children with Sanfilippo syndrome Type A typically experience progressive global developmental delay, followed by the loss of cognitive, language, and motor function, ultimately leading to early death.

The disease is estimated to affect approximately 3,000 to 5,000 patients in commercially accessible geographies, with a median life expectancy of 15 years. The disease is caused by a deficiency of the sulfamidase (SGSH) enzyme, which results in the accumulation of heparan sulfate substrate in cells and progressive damage to the Central Nervous System (CNS). FAYUVI is a single-dose intravenous AAV9 gene therapy designed to deliver a functional copy of the deficient enzyme gene that can express and replace the SGSH enzyme.

Glenn O’Neill, President and Co-Founder, Cure Sanfilippo Foundation, and Terri Klein, CNPM, MPA, President and Chief Executive Officer, National MPS Society, said, “The US FDA approval of FAYUVI is a milestone that the Sanfilippo syndrome Type A community spent decades fighting to achieve: the first-ever treatment for a disease that relentlessly steals a child’s abilities, independence, and future. This remarkable scientific achievement is the culmination of decades of advocacy, fundraising, collaboration, and perseverance across the Sanfilippo community along with researchers, clinicians, and industry partners who never lost faith that progress was possible. We celebrate by honoring every family who contributed and remembering the children we lost while waiting for this day. Together, we look ahead with renewed hope knowing that this treatment is now approved for children and families affected by this heartbreaking disease.”