This study investigates the effects of an investigational medication on slowing the progression of Duchenne muscular dystrophy (DMD) in boys with specific genetic mutations. Duchenne muscular dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness. The study aims to assess how the investigational medication affects walking, muscle function, and quality of life in children with DMD.
Participants will undergo various tests to evaluate their muscle function, including walking tests and assessments of upper and lower limb strength. Some participants will also have magnetic resonance imaging (MRI) at certain locations to further evaluate muscle health. The study will also monitor the safety of the investigational medication over a period of time.
- Who can participate: Boys diagnosed with nonsense mutation DMD confirmed by medical history and genotyping are eligible. Participants must be able to stand, walk, climb, and descend stairs, and have been on corticosteroid treatment for at least 12 months.
- Study details: Participants will take part in tests to measure walking and muscle function. Some may have MRIs if they are at participating sites. A placebo is not used in this study. A placebo is an inactive substance that looks like the investigational medicine/vaccine but does not contain any medicine.
- Study Timelines: The study will last 144 weeks.

