NS-089/NCNP-02-201 in Boys With Duchenne Muscular Dystrophy (DMD)

Who May Qualify: - Male ≥ 4 years and \<15 years of age - Confirmed DMD mutation(s) in the dystrophin gene that is amenable to skipping of exon 44 to restore the dystrophin mRNA reading frame - Able to walk independently without assistive devices - Ability to complete the TTSTAND without assistance in \<20 seconds - Stable dose of glucocorticoid for at least 3 months and the dose is expected to remain on a stable dose for the duration of the study. - Other inclusion criteria may apply. Who Should NOT Join This Trial: - Has a body weight of \<20 kg at the time of willing to sign a consent form (applies to participants screening for Part 1 only) - Evidence of symptomatic cardiomyopathy - Current or previous treatment with anabolic steroids (e.g., oxandrolone) or products containing resveratrol or adenosine triphosphate within 3 months prior to first dose of study drug - Current or previous treatment with any other investigational drug within 3 months prior to the first dose of study drug or within 5 times the half-life of a medication, whichever is longer - Surgery within the 3 months prior to the first dose of study drug or planned during the study duration - Previously treated in an interventional study of NS-089/NCNP-02 - Having received exon skipping oligonucleotide within 1 year prior to the first dose of IP - Other exclusion criteria may apply. Always talk to your doctor about whether this trial is right for you.