Effects of fasudil on disease spreading in ALS - A MUNIX-based post-hoc analysis of the ROCK-ALS trial

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the spread of muscle weakness across body regions. ROCK-ALS was a multicenter, placebo-controlled phase 2 trial assessing the safety, tolerability, and efficacy of the Rho kinase inhibitor fasudil in ALS patients. A key exploratory objective was to evaluate fasudil's effect on the spread of muscle weakness using the Motor Unit Number Index (MUNIX), an established, quantitative electrophysiological biomarker of lower motor neuron integrity. MUNIX was assessed in 10 muscles at baseline, day 26, day 90, and day 180. In the present post-hoc analysis, correlations were assessed between baseline serum biomarkers-neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP)-and baseline clinical measures (ALSFRS-R, slow vital capacity, and MUNIX-10 sum scores) as well as their monthly rates of change, to explore potential prognostic relationships. For the analysis of disease spreading, muscles were classified as newly affected based on MUNIX decline relative to contralateral values or prior measurements, using thresholds of ≥10%, ≥20%, or ≥30%. Out of 118 participants included in the intention-to-treat population, 78 had full MUNIX datasets at baseline, and 67 had at least one follow-up. Baseline MUNIX-10 sum scores correlated with subsequent ALSFRS-R decline, suggesting prognostic value. Additionally, at day 90, fasudil significantly reduced the number of newly affected muscles compared to placebo in a dose-dependent manner over different thresholds. This supports MUNIX as a sensitive biomarker for monitoring disease spreading and demonstrates that fasudil may attenuate the progression of lower motor neuron involvement in ALS. Trial registration number: NCT03792490 (ClinicalTrials.gov); 2017-003676-31 (Eudra-CT).