The Food and Drug Administration (FDA) has granted Fast Track designation for an investigational single treatment for mucopolysaccharidosis type 1 (MPS 1), a rare autosomal recessive genetic disease caused by deficiency of the enzyme iduronidase (IDUA). 

RGX-111 (Regenxbio) is a novel gene therapy designed to directly deliver the human IDUA gene to the CNS using the NAV AAV9 vector; this could potentially provide a permanent source of secreted IDUA, allowing for long-term cross-correction of cells throughout the CNS.

A Phase 1 clinical study in adults and children with MPS 1 is being planned. Approximately 5 subjects with MPS 1 will be treated in 2 dose cohorts (2 x 109 GC/g brain mass and 1 x 1010 GC/g brain mass); patients will be administered a single dose of RGX-111 via injection directly in the cerebrospinal fluid. Adverse events, lab measures, and neurological examinations will be the primary endpoints. 

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“We are encouraged to see the FDA recognize important research that explores new treatment options for people with MPS 1,” said Steve Holland, board member of the National MPS Society. 

Current treatments for MPS 1 include bone marrow transplant and enzyme replacement with a recombinant form of human IDUA administered intravenously. 

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