Safety and Dose Finding Study of NS-065/NCNP-01 in Boys With Duchenne Muscular Dystrophy (DMD)

This is a Phase II, multiple center, 2-period, randomized, placebo-controlled, dose finding study of NS-065/NCNP-01 administered by infusion once weekly for 24 weeks to ambulant boys ages 4-\<10 years with DMD. Two dose level cohorts will be enrolled. Period 1 of this study will be conducted in a double-blind fashion. Randomized patients will receive weekly IV infusions of NS-065/NCNP-01 or placebo for the first 4 weeks of their participation (Period 1) and NS-065/NCNP-01 by IV infusion for weeks 5-24 (20 weeks of active treatment - Period 2). Analysis of safety data from Period 1 of the 40mg/kg dose cohort will be completed prior to enrolling patients in the 80mg/kg dose cohort. Patients completing the 24-week study will be eligible for an open-label extension study. Clinical efficacy will be assessed at regularly scheduled study visits, including functional tests such as the six-minute walk test (6MWT), time to stand (TTSTAND), time to run/walk 10 meters (TTRW), time to climb 4 stairs (TTCLIMB) and quantitative muscle testing (QMT). All patients will undergo a muscle biopsy of the bicep at baseline and a second muscle biopsy at Week 24. Safety will be assessed through the collection of adverse events (AEs), blood and urine laboratory tests, electrocardiograms (ECGs), vital signs, and physical examinations throughout the study. Serial blood samples will be taken at four of the study visits to assess the pharmacokinetics of the study drug.