This clinical trial is focused on studying Duchenne Muscular Dystrophy, a genetic disorder characterized by progressive muscle weakness and degeneration. The treatment being tested is called Vesleteplirsen (SRP-5051), which is administered through an intravenous infusion. This means the medication is given directly into a vein. The study aims to determine the best dose of Vesleteplirsen and to evaluate its effects on the levels of a protein called dystrophin in the muscles. Dystrophin is important for muscle strength and function, and the study is particularly interested in patients whose condition can benefit from a specific type of genetic treatment known as exon 51-skipping.

The study is divided into two parts. In the first part, participants will receive different doses of Vesleteplirsen to find the highest dose that can be tolerated safely. This part will help researchers understand how the body handles the medication and its safety profile. In the second part, participants will receive the dose determined from the first part, and researchers will measure the amount of dystrophin in the muscle tissue to see how well the treatment is working. The medication is given every four weeks, and the study will monitor participants over a period of time to gather comprehensive data.

Throughout the study, researchers will also keep track of any side effects or adverse events that participants may experience. This information is crucial for understanding the safety and effectiveness of Vesleteplirsen in treating Duchenne Muscular Dystrophy. The study is designed to provide valuable insights into how this treatment can potentially improve muscle function and quality of life for those affected by this condition.