A Study to Assess Vamorolone in Becker Muscular Dystrophy (BMD)

This Phase II pilot study is a randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, PK, PD, and exploratory clinical efficacy of vamorolone 500mg (250mg for body weight \<50 kg) daily administered orally compared to placebo over a treatment period of 24 weeks in males with BMD. The study is comprised of a Pretreatment Screening Period of up to 5 weeks duration (unless extended to accommodate varicella vaccination), a 1-day Pretreatment Baseline Period, a 24-week Treatment Period, and a 4-week Dose-tapering Period (for subjects not continuing directly with further vamorolone treatment). Subjects will be enrolled into this study at the time written informed consent is given, and administered study medication only after completion of all Pretreatment Screening assessments to confirm eligibility. Subjects will be assessed for safety, tolerability, PK, PD, and effect on physical functioning at scheduled visits throughout the study. Screening assessments will be performed prior to baseline assessments on Day -1 and first administration of study medication on Day 1. After completion of Screening and Baseline assessments, subjects will return to the study clinic on Day 1 for safety, PK and PD assessments prior to administration of the first dose of study medication. Additional on-site study visits will occur at Week 4, Week 12, and Week 24. Adverse events, including serious adverse events (SAEs), and concomitant medications will be recorded throughout the study. A Data and Safety Monitoring Board (DSMB) will review SAEs and other pertinent safety data at regular intervals during the study, and make recommendations to the Sponsor and Study Team regarding study conduct. Subject diaries will be dispensed at the Day 1, Week 12, and Week 24 (for subjects participating in the Dose-tapering Period) Visits to record AEs, changes to concomitant medications taken during the study, and any missed or incomplete doses of study medication. The scheduled Week 12 and Week 24 assessments may be performed over a 2-day period, if necessary, to facilitate scheduling. Subjects who complete the VBP15-BMD-001 study assessments through the Week 24 Visit may be given the opportunity to continue to receive vamorolone as part of an expanded access or compassionate use program. Subjects who complete the VBP15-BMD-001 study and will enroll directly into an expanded access or compassionate use program to continue vamorolone treatment will be discharged from the VBP15-BMD-001 study following completion of all Week 24 assessments. Subjects who will not continue vamorolone treatment in the expanded access or compassionate use program will have their study medication dose tapered during a 4-week Dose-tapering Period to taper study medication prior to discharge from the study. For these subjects, site study staff will contact the subject or parent(s)/guardian(s) by telephone at Week 26 to ensure that the dose tapering is proceeding according to protocol, to assess potential signs or symptoms of adrenal suppression, and to address any questions the subject or parent(s)/guardian(s) may have. In the event that any clinical or laboratory parameters remain abnormal at the time of discharge from the study, the subject will be followed medically, as clinically indicated. Any subject who discontinues the study prior to the Week 24 Visit should return to the study unit for scheduled Week 24 assessments at the time of early withdrawal and a Week 28 Visit following the taper, whenever possible, assuming the subject has not withdrawn consent. Any subject who withdraws early from the study after study medication dosing has begun should undergo dose-tapering following early completion of the Week 24 assessments and a Week 28 Visit following the taper.