Barriers to Novel Therapeutics in Amyotrophic Lateral Sclerosis

Abstract

Amyotrophic lateral sclerosis is a devastating neurodegenerative condition primarily involving the motor system in the cerebral cortex, brain stem and spinal cord, but can, in later disease stages, also affect distinct extramotor brain regions. In this article, we discuss the prevalent barriers, including clinical and genetic variability of amyotrophic lateral sclerosis, frailty of the current mouse model and inadequateness of clinical trials, in the search for novel therapeutics. Approaches in terms of understanding the pathogenesis, and the search for biomarkers to initiate early or even presymptomatic treatment and monitor treatment effects are highlighted.Amyotrophic lateral sclerosis (ALS) is a multisystem disease that not only affects the motor system, but also involves other brain areas such as the frontal lobes.The clinical ALS spectrum includes variable phenotypes that are defined by the affected body regions, involvement of the upper and lower motoneurons, and the speed of symptom progression.At present, riluzole is the only US FDA-approved drug for ALS. Its effect on survival is only moderate (2-3 months), augmenting the need for a more effective treatment.A large number of other compounds have not proven effective in clinical trials, owing to an incomplete understanding of the pathogenesis, phenotypic and genetic variability, and poor translation from animal models to humans.Various neurophysiological, biochemical and imaging biomarkers are currently being developed to support early diagnosis, monitor treatment effects and disease progression, and thus, improve the quality of clinical trials.