Genetic and Mechanistic Insights Inform Amyotrophic Lateral Sclerosis Treatment and Symptomatic Management: Current and Emerging Therapeutics and Clinical Trial Design Considerations

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting both upper and lower motor neurons. ALS is classically characterized by painless progressive weakness, causing impaired function of limbs, speech, swallowing, and respiratory function. The disease is fatal within 2-4 years, often the result of respiratory failure. The pathologic hallmark for a majority of ALS cases is aberrant cytoplasmic accumulations of the nuclear protein TAR-DNA binding protein (TDP-43). A total of 10-15% of ALS can be attributed to a single gene mutation, known as genetic or "familial" ALS, while the remainder of cases are termed nongenetic or "sporadic" although heritability has been measured in up to 37% in this population. Complex interactions between genetics, environment, and physiologic susceptibility are thought to contribute to disease. Management is primarily supportive in nature, though there are several approved treatments worldwide. This review details the mechanisms and evidence of approved disease-modifying treatments, relevant measures to track disease burden and progression used in clinical trials, and approaches to pharmacologic management of common symptoms in ALS. As there is not currently a cure for ALS, research into the complex pathophysiologic and genetic alterations contributing to disease is of great interest. This review further discusses the current understanding of genetic etiologies and altered physiology leading to disease, such as neuroinflammation, integrated stress response, aberrant proteostasis and mitochondrial dysfunction, among others. The translation of preclinical discoveries into current investigational therapeutics, novel therapeutic categories such as antisense oligonucleotides and stem cell transplantation, as well as future horizons harnessing the power of artificial intelligence in drug development and clinical trials are discussed.