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

Inclusion Criteria:

• Male ≥ 4 years and <15 years of age

• Confirmed DMD mutation(s) in the dystrophin gene that is amenable to skipping ofexon 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 toremain on a stable dose for the duration of the study.

• Other inclusion criteria may apply.

Exclusion Criteria:

• Has a body weight of <20 kg at the time of informed consent (applies to participantsscreening for Part 1 only)

• Evidence of symptomatic cardiomyopathy

• Current or previous treatment with anabolic steroids (e.g., oxandrolone) or productscontaining resveratrol or adenosine triphosphate within 3 months prior to first doseof study drug

• Current or previous treatment with any other investigational drug within 3 monthsprior to the first dose of study drug or within 5 times the half-life of amedication, whichever is longer

• Surgery within the 3 months prior to the first dose of study drug or planned duringthe study duration

• Previously treated in an interventional study of NS-089/NCNP-02

• Having taken any gene therapy or other exon-skipping oligonucleotide

• Other exclusion criteria may apply.