HMI-203

HMI-203 is an investigational, one-time in vivo gene therapy developed by Homology Medicines for the treatment of mucopolysaccharidosis II (MPS II; Hunter syndrome), a rare X-linked lysosomal storage disorder. The therapy uses a recombinant adeno-associated virus vector (AAVHSC15) to deliver functional copies of the human iduronate-2-sulfatase (IDS) gene to multiple organs. This enables production of the I2S enzyme, which is responsible for breaking down glycosaminoglycans (GAGs). Accumulation of GAGs leads to progressive debilitation and shortened life expectancy in people with Hunter syndrome. Preclinical studies demonstrated robust biodistribution, sustained expression of I2S across disease-relevant tissues, reduction in key biomarkers such as heparan sulfate GAGs and LAMP-1, and phenotypic correction in animal models following a single intravenous administration[1][5][6][7][8].