Generalizability of Edaravone Efficacy

The pivotal phase 3 trial MCI186-19 (Study 19) demonstrated the efficacy of intravenous edaravone in slowing functional decline in patients with amyotrophic lateral sclerosis (ALS), leading to United States Food and Drug Administration approval. Study 19 utilized a targeted enrollment enrichment strategy based on post hoc analyses from earlier trials, selecting patients with higher baseline function, more rapid disease progression, and better respiratory status. To evaluate the generalizability of Study 19 results, subsequent post hoc analyses assessed the efficacy of edaravone in broader ALS populations. One machine learning-based analysis retrospectively applied a validated model to Study 16 data, stratifying patients by predicted risk of respiratory decline. This detectable effect cluster analysis suggested that up to 70% of Study 16 participants may have benefited from edaravone. A second analysis investigated edaravone efficacy in patients from Study 19 with forced vital capacity (FVC) < 80% predicted (%p) at the start of treatment, since FVC ≥ 80%p was one of the Study 19 inclusion criteria. Both high- and low-FVC subgroups demonstrated reduced ALS functional rating scale-revised decline at 48 weeks when treated continuously with edaravone. These findings support the potential benefit of edaravone in a wider range of patients with ALS than those enrolled in Study 19, providing important insights into how clinical trial enrichment strategies may influence perceived efficacy, and underscoring the need for future prospective studies in more diverse ALS populations.