Passage Bio, Inc. announced that U.S. Food and Drug Administration (FDA) has cleared an investigational new drug (IND) application for the company's lead product candidate, PBGM01, an adeno-associated virus (AAV)-delivery gene therapy that is being studied for the treatment of infantile GM1 gangliosidosis (GM1). GM1 is a rare and often life-threatening CNS disorder with no approved disease-modifying therapies available. The company expects to dose the first patient for the global PBGM01 clinical trial program in the first quarter of 2021. GM1, a rare monogenic lysosomal storage disease, is caused by mutations in the GLB1 gene, which encodes the lysosomal enzyme beta -galactosidase (β-gal). Reduced β-gal activity results in the accumulation of toxic levels of GM1 in neurons throughout the brain, causing rapidly progressive neurodegeneration. GM1 manifests with hypotonia (reduced muscle tone), progressive CNS dysfunction, and rapid developmental regression. Life expectancy for infants with GM1 is two to four years, and infantile GM1 represents approximately 60% of the global GM1 incidence of 0.5 to 1 in 100,000 live births.