The preclinical discovery and development of edaravone for the treatment of amyotrophic lateral sclerosis: what lessons have we learnt?

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron loss, with limited therapeutic options. Among the few approved drugs, edaravone, a free radical scavenger developed originally for ischemic stroke, has attracted particular attention for its ability to counteract oxidative stress, a key driver of neurodegeneration. Its amphipathic structure and ability to cross the blood-brain barrier support its potential neuroprotective action. AREAS COVERED: The authors discuss preclinical studies demonstrating edaravone's ability to reduce oxidative damage, preserve mitochondrial function, and modulate neuroinflammatory responses in ALS cellular and animal models. They discuss variations in dosage, timing, and disease models that produced heterogeneous results. In transgenic mice, edaravone may delay symptom onset and modestly extend survival, but these effects are inconsistent and often limited to early disease stages. EXPERT OPINION: Clinically, edaravone provides modest benefits in a subset of patients, reflecting the translational gap between preclinical efficacy and clinical relevance. This case highlights broader challenges in ALS drug discovery, including limited model predictivity, methodological variability, and lack of patient stratification. The edaravone experience highlights key lessons for future neuroprotective approaches: the importance of standardized preclinical design, integration of human-based models, early pharmacokinetic validation, and biomarker-driven trials to advance precision neuroprotection in ALS.