Sio Gene Therapies Inc. announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to AXO-AAV-GM1, its adeno-associated viral vector (AAV)9-based gene therapy candidate for the treatment of Type I (early infantile onset) and Type II (late infantile-onset and juvenile-onset) GM1 gangliosidosis. The Fast Track process is designed to facilitate the development and expedite the review of drugs to treat serious conditions and fill an unmet medical need. The current Phase 1/2 study (NCT03952637) is designed to evaluate the safety, tolerability, and potential efficacy of AXO-AAV-GM1 gene therapy delivered intravenously in children with early infantile, or Type I, and late infantile and juvenile, or Type II, GM1 gangliosidosis. Stage 1 of the study is a dose-escalation study in which the low-dose cohort is evaluating 1.5x1013 vg/kg and the high-dose cohort is evaluating a dose of 4.5x1013 vg/kg. Stage 2 of the trial will then evaluate the efficacy and safety of the optimal dose identified in Stage 1. GM1 gangliosidosis is a progressive and fatal pediatric lysosomal storage disorder caused by mutations in the GLB1 gene that cause impaired production of the ?-galactosidase enzyme. Currently, there are no FDA-approved treatment options for GM1 gangliosidosis. AXO-AAV-GM1 delivers a functional copy of the GLB1 gene via an adeno-associated viral (AAV) vector, with the goal of restoring ?-galactosidase enzyme activity for the treatment of GM1 gangliosidosis. The gene therapy is delivered intravenously, which has the potential to achieve a broad central and peripheral biodistribution. Preclinical studies in murine and a naturally-occurring feline model of GM1 gangliosidosis have supported AXO-AAV-GM1?s ability to increase ?-galactosidase enzyme activity, reduce GM1 ganglioside accumulation, improve neuromuscular function, and extend survival. AXO-AAV-GM1 has received both Orphan Drug Designation and Rare Pediatric Disease Designation from the FDA and is the only gene therapy in clinical development for all pediatric forms of GM1 gangliosidosis. In 2018, Sio licensed exclusive worldwide rights from UMass Chan Medical School for the development and commercialization of gene therapy programs for GM1 gangliosidosis and GM2 gangliosidosis, including Tay-Sachs and Sandhoff diseases.