Vamorolone for Duchenne Muscular Dystrophy: A Cross-Trial Efficacy Comparison With Classic Corticosteroids From the FOR-DMD Trial.

Abstract

Vamorolone demonstrated similar efficacy for Duchenne muscular dystrophy (DMD) compared with prednisone in a 24-week exploratory analysis and may reduce key side effects compared with classic corticosteroids. In this study, we compare the efficacy and anthropometric effect of vamorolone 6 mg/kg/d with prednisone 0.75 mg/kg/d and deflazacort 0.9 mg/kg/d in steroid-naïve boys aged 4 to <7 years using data from 2 trials. VISION-DMD was a phase 2b, 48-week randomized, double-blind trial assessing vamorolone 2 and 6 mg/kg/d vs placebo and prednisone 0.75 mg/kg/d to 24 weeks. Finding the Optimum Steroid Regimen for DMD (FOR-DMD) was a double-blind, parallel-group randomized trial comparing daily prednisone 0.75 mg/kg/d, daily deflazacort 0.9 mg/kg/d, and intermittent prednisone 0.75 mg/kg (10/10 days on/off). Entropy balancing generated weighted data for mixed model for repeated measures analyses that compared VISION-DMD vamorolone 6 mg/kg/d efficacy and anthropometric outcomes with FOR-DMD prednisone and deflazacort outcomes at 6 and 12 months. Inclusion criteria were boys with genetically confirmed DMD, age 4 to <7 years, ambulatory, and able to complete a time-to-stand (TTSTAND) assessment in <10 seconds at baseline. All interventions showed motor improvements relative to baseline at 6 and 12 months. Using the weighted cohorts and at 12 months, vamorolone 6 mg/kg/d (n = 28) had similar changes in TTSTAND velocity, the primary motor endpoint component in both trials, vs daily prednisone (n = 50) or deflazacort (n = 55; mean baseline age 5.42 years all groups), but with CIs overlapping minimal clinically important thresholds of 0.023 rises per second (TTSTAND velocity least squares mean [LSM] difference [95% CI]: vamorolone 6 mg/kg/d vs prednisone 0.75 mg/kg/d, 0.004 rises per second [-0.025 to 0.032] and vs deflazacort 0.9 mg/kg/d, 0.001 rises per second [-0.027 to 0.028]). Body mass index (BMI) <i>Z</i>-scores increased in all groups, greatest with vamorolone (12-month LSM difference [95% CI]: vamorolone vs prednisone 0.57 [0.24-0.90]; vamorolone vs deflazacort 0.29 [0.03-0.56]), whereas growth slowdown occurred in prednisone- and deflazacort-treated boys but not vamorolone (12-month LSM difference in height <i>Z</i>-scores [95% CI]: vamorolone vs prednisone 0.57 [0.24-0.90]; vamorolone vs deflazacort 0.72 [0.53-0.91]). Vamorolone demonstrated numerically similar TTSTAND velocity changes to prednisone and deflazacort at 1 year; however, interpretations of differences are limited by 95% CIs crossing minimally important difference thresholds. Further evidence of the growth-protective effect of vamorolone was observed; however, all treatments increased BMI. Vamorolone provides a linear growth-protective classic corticosteroid alternative. NCT03439670; NCT01603407. This Class III study did not definitively identify differences in efficacy between vamorolone and classic corticosteroids but found that vamorolone protects linear growth in boys with DMD.