AAV-based gene therapy with modified HEXB confers lasting therapeutic benefits in GM2 gangliosidosis models

GM2 gangliosidoses, including Tay-Sachs (TSD) and Sandhoff (SD) diseases, are lysosomal storage disorders with neurological manifestations caused by the excessive accumulation of GM2 ganglioside due to the deficiency of the β-hexosaminidase A (HexA). Although gene therapy approaches are underway, concerns regarding efficacy and safety remain. Here, we evaluate a tyrosine-mutant adeno-associated virus serotype 9 (AAV9/3) vector encoding modified HEXB (modHEXB) wherein nine amino acid residues are substituted from HEXA. The intracerebroventricular administration of AAV9/3-modHEXB in SD mice results in modHexB expression in the brain, reduces GM2 accumulation, and attenuates neuroinflammation. Furthermore, AAV9/3-modHEXB rescues motor function, and longer lifespan in SD mice. In addition, intrathecal administration in non-human primates and rats demonstrates broad biodistribution and an overall favorable safety profile. These findings support the translational potential of AAV9/3-modHEXB as a gene therapy approach for TSD and SD.