A Study to Evaluate the Safety and Tolerability of GEN6050X in Duchenne Muscular Dystrophy.

The study will evaluate the safety and tolerability of GEN6050X gene therapy in Duchenne muscular dystrophy (DMD) patients amenable to exon 50 skipping.

GEN6050X is an intravenously administered human DMD exon 50 skipping base editing drug containing dual single-stranded adeno-associated virus serotype 9 (ss.AAV9) vectors. The study is a first-in-human, single-arm, open-label, single-center clinical trial to evaluate safety and tolerability of a single intravenous infusion of GEN6050X in ambulatory boys with DMD. Other objectives include pharmacokinetics, pharmacodynamics, and the preliminary clinical efficacy of GEN6050X over 52 weeks. A total of three ambulatory pediatric participants (aged 4 to 9 years old) are expected to enroll, each receiving a dose of 5×10\^13 vg/kg. These participants will be dosed in a staggered fashion. Safety assessments will include monitoring of adverse events (AEs), laboratory tests, electrocardiograms (ECGs), vital signs, and physical examinations throughout the study duration. In addition, a comprehensive short-term prophylactic immunosuppression regimen(including rituximab and sirolimus) will be administered prior to treatment in order to mitigate potential immune response.