This Phase II study is an open-label, multiple dose study to evaluate the safety, tolerability, PK, PD, clinical efficacy, behavior and neuropsychology, and physical functioning of vamorolone administered orally at daily doses of 2.0 mg/kg and 6.0 mg/kg over a treatment period of 3 months in steroid-naïve boys ages 2 to <4, and glucocorticoid-treated and currently untreated boys ages 7 to <18 years with DMD.~The study is comprised of a 5-week Pretreatment Screening Period; a 1-day Pretreatment Baseline Period; a 3-month open-label Treatment Period (Weeks 1-12); and a 4-week open-label Dose-tapering Period (Weeks 13-16) for subjects who will not transition directly to further vamorolone or standard of care (SoC) glucocorticoid treatment at the end of the study.~Subjects will be enrolled into the study at the Screening Visit, at the time written informed consent is obtained.~Within the 2 to <4 years age group, the initial 10 eligible subjects will be assigned to the 2.0 mg/kg/day treatment group at the Baseline Day -1 Visit. The subsequent 10 eligible subjects will be assigned to the 6.0 mg/kg/day treatment group at the Baseline Day -1 Visit.~Within the 7 to <18 years age group, both corticosteroid-treated and untreated, the initial 12 eligible subjects will be assigned to the 2.0 mg/kg/day treatment group at the Baseline Day -1 Visit. The subsequent 12 eligible subjects will be assigned to the 6.0 mg/kg/day treatment group at the Baseline Day -1 Visit.~The first 6 subjects in each age group at 2 mg/kg will serve as the PK/safety run-in cohorts. PK assessments will be performed at week 2 and together with the safety assessment during the first 4 weeks of treatment this will be the basis to confirm whether 2 and 6 mg/kg/day will be used in the subsequent patients or if a dose adjustment is needed to avoid over or under-exposure in patients for any of the two age groups.~Glucocorticoid-treated subjects in the 7 to <18 years age group will take their final dose of SoC glucocorticoid therapy for DMD on Baseline Day -1, within 24 hours prior to administration of the first dose of vamorolone study medication.~All subjects in both age groups will begin their assigned vamorolone treatment on Treatment Period Day 1, and will continue to receive their assigned vamorolone treatment throughout the duration of the 3 month Treatment Period (Weeks 1-12).~At the end of the 3-month Treatment Period (Week 12), subjects will be given the option to receive vamorolone in an expanded access or compassionate use program, if possible, or to transition to SoC treatment for DMD (may include glucocorticoids). Subjects completing VBP15-006 and enrolling directly into the expanded access or compassionate use program or transitioning directly to SoC glucocorticoid treatment will not need to taper their vamorolone dose prior to participation in the expanded access or compassionate use program or initiation of SoC glucocorticoid treatment. All subjects who will not transition directly to further vamorolone or SoC glucocorticoid treatment will begin a 4 week open label Dose tapering Period during which the dose of study medication will be progressively reduced and discontinued.
This Phase II study is an open-label, multiple dose study to evaluate the safety, tolerability, PK, PD, clinical efficacy, behavior and neuropsychology, and physical functioning vamorolone over a treatment period of 12 weeks in steroid-naïve boys ages 2 to <4 years, and glucocorticoid-treated and currently untreated boys ages 7 to <18 years with DMD.