GB-501

GB-501 is a preclinical-stage adeno-associated virus (AAV) gene therapy designed to treat corneal clouding associated with mucopolysaccharidosis type 1 (MPS1). MPS1 is a rare lysosomal storage disorder caused by a deficiency in the enzyme alpha-L-iduronidase (IDUA), which leads to the accumulation of glycosaminoglycans (GAGs) in various tissues, including the cornea. GB-501 delivers a functional gene sequence encoding the IDUA enzyme, aiming to restore enzymatic activity and clear corneal GAG deposits. Originally developed by RainBio and licensed from the University of North Carolina at Chapel Hill, the program was acquired by Graybug Vision in March 2022. Preclinical studies in canine models demonstrated complete and sustained clearing of the cornea. However, development of the program was halted in August 2022 following a strategic review by Graybug Vision and its subsequent merger with CalciMedica.