Efficacy and Safety of Vamorolone in Duchenne Muscular Dystrophy

Abstract

Vamorolone is a synthetic steroidal drug with potent anti-inflammatory properties. Initial open-label, multiple ascending dose-finding studies of vamorolone among boys with Duchenne muscular dystrophy (DMD) found significant motor function improvement after 6 months treatment in higher-dose (ie, 2.0 mg/kg/d) groups. OBJECTIVE To investigate outcomes after 30 months of open-label vamorolone treatment. DESIGN, SETTING, AND PARTICIPANTS This nonrandomized controlled trial was conducted by the Cooperative International Neuromuscular Research Group at 11 US and non-US study sites. Participants were 46 boys ages 4.5 to 7.5 years with DMD who completed the 6-month dose-finding study. Data were analyzed from July 2020 through November 2021. INTERVENTIONS Participants were enrolled in a 24-month, long-term extension (LTE) study with vamorolone dose escalated to 2.0 or 6.0 mg/kg/d. MAIN OUTCOMES AND MEASURES Change in time-to-stand (TTSTAND) velocity from dosefinding baseline to end of LTE study was the primary outcome. Efficacy assessments included timed function tests, 6-minute walk test, and NorthStar Ambulatory Assessment (NSAA). Participants with DMD treated with glucocorticoids from the Duchenne Natural History Study (DNHS) and NorthStar United Kingdom (NSUK) Network were matched and compared with participants in the LTE study receiving higher doses of vamorolone. RESULTS Among 46 boys with DMD who completed the dose-finding study, 41 boys (mean [SD]