Overview

This is a Phase 2, open-label, multi-center, 2-part study of NS-089/NCNP-02 administered by weekly IV infusion to ambulant boys aged ≥4 to <15 years with DMD due to mutations amenable to exon 44 skipping. Participants will receive a selected dose of NS-089/NCNP-02 administered once weekly.

The study consists of 2 parts: Part 1 and Part 2. Six participants (Cohort 1) will participate in both Part 1 and Part 2, and 14 participants (Cohort 2) will be added for Part 2.

Eligibility

Inclusion Criteria:

• 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 <7 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.

Exclusion Criteria:

• Has a body weight of <20 kg at the time of informed consent (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 taken any gene therapy or other exon-skipping oligonucleotide
• Other exclusion criteria may apply.