Introduction to the Supplement.

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neuromuscular disease with marked phenotypic and clinical heterogeneity. Three active pharmaceutical agents are currently approved by the United States Food and Drug Administration (FDA) for ALS: riluzole, edaravone (including intravenous [IV] and oral suspension formulations), and tofersen. Study MCI186-19 (Study 19) was a pivotal, phase 3 randomized controlled trial that demonstrated a significant reduction in physical functional decline vs. placebo in Japanese patients with ALS and contributed to FDA approval of IV edaravone in 2017. Edaravone oral suspension was FDA-approved in May 2022 following the results of Study MT-1186-A01, which showed it was well tolerated with a safety profile consistent with IV edaravone. Following Study 19, the clinical benefit of edaravone has remained an active area of investigation. This supplement presents data from clinical trials, post hoc analyses, and clinical studies that expand understanding of the use of edaravone in broader ALS populations. Topics include safety in clinical practice, generalizability of efficacy, clinical treatment outcomes, and health economics and outcomes research studies. Together, these findings aim to inform clinicians, researchers, and stakeholders regarding the evolving evidence base for edaravone in the management of ALS.