Targeting TDP-43 in sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive neurodegenerative disorder characterized by motor neuron degeneration leading to early mortality. Despite advances in understanding genetic and molecular contributors, effective disease-modifying therapies for sporadic ALS are of limited utility. The identification of the accumulation of TAR DNA-binding protein 43 (TDP-43) in 97% of total ALS cases represents a critical pathogenic hallmark. This review examines key biological mechanisms underlying TDP-43 pathology, emerging therapeutic strategies, and evolving approaches to clinical trial design and biomarker development. TDP-43 loss of nuclear function, leading to widespread RNA missplicing, and inclusion of cryptic exons, represents an early and critical event in ALS pathogenesis causing downstream dysregulation of key neuronal genes such as STMN2 and UNC13A contributing to axonal degeneration and synaptic dysfunction. Therapeutic strategies targeting these pathways are currently under investigation. Additional approaches aim to ameliorate TDP-43 gain-of-function through cytoplasmic TDP-43 aggregation or modulating processes such as stress responses and RNA metabolism, although clinical translation has been challenging. Advances in biomarkers, including neurofilament light chain and cryptic exon-derived peptides, provide tools for developing efficient clinical trials. However, heterogeneity in disease progression and limitations of available clinical endpoints complicate trial design. Integration of biological insights with biomarker-driven patient stratification and optimized trial methodologies is essential to improve clinical trial outcomes. Emerging biomarkers may enable earlier diagnosis, monitoring of therapeutic response, and personalized treatment approaches. Continued alignment of biological discovery with innovative clinical trial design holds promise for advancing effective therapies and transforming the future of ALS.