Anchoring ALS Prognosis: Neurofilament Light Chain Outperforms Inflammatory, Metabolic, and CNS Barrier Biomarkers in the METABALS Cohort

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and fatal neurodegenerative disorder with marked biological heterogeneity. Despite extensive research, reliable prognostic biomarkers remain limited, with neurofilament light chain (NfL) being the only marker increasingly implemented in clinical practice. The objective of this study is to assess and compare the prognostic value of NfL, circulating markers of central nervous system (CNS) barrier dysfunction, inflammatory mediators, kynurenine pathway metabolites, and global metabolomic profiles in patients with ALS. Seventy-two patients with ALS from the prospective multicenter METABALS cohort were included. Serum, cerebrospinal fluid (CSF), and urine samples were collected at diagnosis. NfL concentrations, markers of blood-brain and blood-spinal cord barrier permeability (albumin quotient, S100B, neuron-specific enolase NSE), 48 inflammatory mediators, kynurenine pathway metabolites, and untargeted metabolomic profiles were measured. Associations with clinical features, disease progression, and survival were investigated using univariate analyses and multivariate models. Serum and CSF NfL concentrations were strongly associated with ALS Functional Rating Scale-Revised scores, respiratory function, diagnostic delay, and survival. Higher serum NfL concentrations at diagnosis predicted shorter survival (ROC AUC = 0.86). In all multivariate and multi-block models, serum NfL was the only biomarker independently associated with survival. Markers of CNS barrier integrity, inflammatory mediators, and metabolomic signatures showed limited prognostic value but provided insights into metabolic remodeling and barrier dysfunction. In this integrated multi-omics study, serum NfL clearly outperformed inflammatory, metabolic, and CNS barrier markers as a prognostic biomarker in ALS, supporting its central role in clinical stratification while complementary biological markers highlighted several relevant pathophysiological mechanisms.