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Ultragenyx to Seek FDA Approval of Gene Therapy for Sanfilippo Syndrome Type A

NEW YORK – Ultragenyx Pharmaceutical on Wednesday said it will file a biologics license application (BLA) seeking accelerated approval of an investigational gene therapy, dubbed UX111, for Sanfilippo syndrome type A (MPS IIIA) late this year or early next year.

The Novato, California-based biopharma firm said it has reached an agreement with the US Food and Drug Administration that measurements of cerebral spinal fluid (CSF) heparan sulfate (HS) could serve as a surrogate endpoint that is reasonably likely to predict the gene therapy's clinical benefit and support a regulatory filing seeking its accelerated approval.

UX111 is an in vivo gene therapy designed to treat MPS IIIA, a rare lysosomal storage disease caused by mutations in the SGSH gene. Patients with MPS IIIA have abnormal accumulation of HS in their brain, which leads to neurodegeneration and early death. The gene therapy, administered intravenously, uses an adeno-associated virus serotype 9 vector to deliver a functional copy of SGSH.

"Gaining alignment with the FDA that CSF HS is a relevant biomarker to enable accelerated approval in Sanfilippo syndrome is a pivotal moment for the community and paves the way for treatments for all fatal types of neuronopathic mucopolysaccharidoses," Ultragenyx President and CEO Emil Kakkis said in a statement.

Ultragenyx still has to finalize details of its regulatory application with the FDA in a pre-BLA meeting, but it plans to submit data on UX111 from existing clinical studies, including an ongoing pivotal Phase I/II/III clinical trial.