Objective: We report 2-year treatment period of vamorolone (VBP15-LTE) versus corticosteroid treatment data from the NorthStar UK (NSUK) Clinical Network and the CINRG Duchenne Natural History Study (DNHS).
Results: The mean TTSTAND, TTRW, and TTCLIMB velocities were not significantly different between the vamorolone-treated VBP-LTE (n=23) and group-matched corticosteroid-treated DNHS participants (n=75). As well, the 2-year change in mean total NSAA scores for vamorolone-treated participants (-0.61± 8.12 [CI -4.65, 3.43]; n=18) was similar to NSUK corticosteroid-treated participants (-0.39 ± 5.29 [CI -1.907, 1.132]; n=49). A relative risk analysis of NSAA scores showed no significant difference in the risk of losing a motor function between the two cohorts: NSUK participants lost 139/1734 functions while VBP15-LTE participants lost 26/335 functions (RR 1.033 [CI 0.691, 1.544]). Nonparametric maximum likelihood estimate of median time to reach a TTSTAND milestone of ?10 seconds for VBP15-LTE participants was >9.31 years (CI 7.51, Inf), for DNHS >9.31 years (CI 8.29, Inf), and for NSUK 9.55 years (CI 8.87, Inf).
Conclusions: Vamorolone showed a disease-modifying effect in boys with DMD, with maintenance of muscle strength and function similar to corticosteroid real-world data observed in the NSUK and DNHS cohorts over a 2-year treatment period.