Why is it so difficult to discover drugs for amyotrophic lateral sclerosis? A protein intrinsic disorder perspective.

INTRODUCTION: Amyotrophic Lateral Sclerosis (ALS) is the most common adult motor neuron disease, now viewed as a spectrum disorder rather than a single entity. Because of the significant person-to-person variability in the disease's biology, driven by both genetic and environmental interactions, finding a single "magic bullet" drug is unlikely. Despite decades of research, only a few ALS drugs have being developed. Drug discovery has a 95% failure rate due to genetic complexity, lack of sensitive biomarkers, diagnostic delays, inadequate animal models, and poor clinical trial design.

AREAS COVERED: This article considers several aspects related to the prevalence of intrinsic disorder in ALS-related proteins and highlights how these features might hinder rational structure-based drug discovery.

EXPERT OPINION: There is a common oversight in current drug discovery methodologies, which is the neglect of intrinsically disordered proteins (IDPs) playing several crucial roles in the pathology of neurodegeneration in general and ALS in particular. Therefore, it seems that the 'one-size-fits-all' approach to ALS is hitting a wall because these 'shapeshifters' of the cellular world are ignored. Consequently, to be more successful in finding drugs treating ALS, gears should be shifted from rational structure-based models to intrinsic disorder-centric approaches.