Exploratory double-blind, parallel-group, placebo-controlled extension study of edaravone (MCI-186) in amyotrophic lateral sclerosis

Following the first phase III study of edaravone for amyotrophic lateral sclerosis (ALS), this extension study was performed to evaluate longer-term efficacy and safety. Patients given edaravone in the first 24-week phase III study (Cycles 1–6) were randomised to edaravone (E-E) or placebo (E-P) in the subsequent 24-week double-blind period (Cycles 7–12). Patients given placebo in phase III were switched to edaravone (P-E). Subsequently, all patients received edaravone for 12 weeks (Cycles 13–15). Efficacy endpoints included revised ALS Functional Rating Scale (ALSFRS-R) score. Analysis populations were the full analysis set (FAS) and the efficacy-expected subpopulation (EESP) defined by post-hoc analysis of the first phase III study. The least-squares mean and standard error of the intergroup difference (E-E vs. E-P) of change in the ALSFRS-R score from Cycles 7–12 was 1.16 ± 0.93 (p = 0.2176) in the FAS, and 1.85 ± 1.14 (p = 0.1127) in the EESP. The ALSFRS-R score changed almost linearly in the E-E group throughout Cycles 1–15 (60 weeks). The incidence of serious adverse events associated with ALS progression was higher in E-E than in E-P. Edaravone might have potential efficacy for up to 15 cycles when used to treat patients in the EESP with careful safety monitoring.