Is vamorolone an effective treatment for duchenne muscular dystrophy?

Duchenne muscular dystrophy is a common muscular dystrophy that impacts boys a symptom onset around a child’s 6th birthday. A clinical trial examines whether vamorolone was linked to long-term disease medication and a decrease in adverse outcomes linked to glucocorticoids.¹

Investigators from the Cooperative International Neuromuscular Research Group ran a nonrandomized controlled trial at 11 study sites in the United States and outside of the country. The participants of the study were boys aged 4.5 to 7.5 years with duchenne muscular dystrophy who had done a 6-month dose-finding study. They were enrolled into a 24-month, long-term extension study with vamorolone dose escalated to 2.0 or 6.0 mg/kg/d. The primary outcome was a change in time-to-stand (TTSTAND) velocity from dose-finding baseline to end of long-term extension study. Efficacy was measured using timed function tests, 6-minute walk test, and NorthStar Ambulatory Assessment (NSAA). They matched and compared the participants with boys treated with glucocorticoids from the Duchenne Natural History Study (DNHS) and NorthStar United Kingdom Network (NSUK).

There were 41 boys who completed both the dose-finding and long-term extension study, who were an average age of 5.3 years. The investigators found that among the 21 participants who were treated with a higher dose of vamorolone there was a decrease in the average TTSTAND velocity from baseline to 30 months (0.206 [0.070] rises/s vs 0.189 (0.124) rises/s), which was not a statistically significant change (−0.011 rises/s; CI, −0.068 to 0.046 rises/s). No statistically significant differences were noted between the participants receiving a higher-dose of vamorolone and those being given glucocorticoid over a 2-year period in NSAA total score change (0.22 units vs NSUK; 95% CI, −4.48 to 4.04]; P = .92), body mass index z score change (0.002 vs DNHS SD/mo; 95% CI, −0.006 to 0.010; P = .58), or timed function test change. Vamorolone was found to be well tolerated in doses up to 6.0 mg/kg/d. Five participants discontinued the drug prematurely, but not as a result of effects linked to the drug. A significant growth delay was seen in participants with DNHS participants when compared to participants who received vamorolone and had stable height percentiles (0.37 percentile/mo; 95% CI, 0.23 to 0.52 percentile/mo) over time.

The investigators concluded that vamorolone was not linked to a change in TTSTAND velocity; was similar to the standard of care glucocorticoid for maintaining muscle strength and function; and improved height velocity. They concluded that with these results that vamorolone could be a good candidate to treat duchenne muscular dystrophy.

Reference

1. Mah J, Clemens P, Guglieri M, et al. Efficacy and safety of vamorolone in duchenne muscular dystrophy: a 30-month nonrandomized controlled open-label extension trial. JAMA Netw Open. 2022;5(1):e2144178. doi:10.1001/jamanetworkopen.2021.44178