GB703

GB703 is an investigational next-generation gene therapy developed by Gemma Biotherapeutics for the treatment of Duchenne muscular dystrophy (DMD). It utilizes a novel myotropic, integrin-binding adeno-associated virus (AAV) capsid, GCap104, to deliver a codon-optimized, de-immunized hybrid microdystrophin payload. A unique feature of GB703 is the replacement of the N-terminal segment of the microdystrophin protein with functionally equivalent self-peptides from utrophin. This design is intended to expand patient eligibility to include those with mutations in exons 8–11, who are typically at high risk for severe immune responses to standard microdystrophin transgenes. Preclinical studies in mouse models and non-human primates have demonstrated robust sarcolemmal expression and protection from muscle degeneration.