An open-label Phase 2a study of fasudil in amyotrophic lateral sclerosis: safety and exploratory endpoints

OBJECTIVES: The primary objective was to assess the safety of oral fasudil in amyotrophic lateral sclerosis (ALS) patients. Changes in serum neurofilament light (NfL) levels and the ratio of phosphorylated to total AKT (pAKT/tAKT) were exploratory endpoints. METHODS: This was a multicenter, open-label study. Two 31-patient cohorts were sequentially enrolled and treated with either 180 mg or 300 mg per day of oral fasudil for 24 weeks. The primary endpoint was safety. Secondary endpoints evaluated changes in the ALS functional rating scale-revised (ALSFRS-R), slow vital capacity, and muscle strength. We also assessed changes in serum NfL and pAKT/tAKT ratios in plasma (neuron-derived) and CSF (total) extracellular vesicles (EVs). RESULTS: Eighty-one percent (25/31) and 71% (22/31) of patients completed 24 weeks of treatment in the 180 and 300 mg cohort, respectively. Fasudil was safe and well tolerated, with predominantly mild drug-related adverse events. Secondary endpoints, though not statistically significant, were directionally consistent with a treatment effect. Exploratory analyses showed a 15.4% reduction in serum NfL at 24 weeks (p = 0.001) in the 180 mg cohort, with no change in the 300 mg cohort (-0.4%, p = 0.990). The NfL reduction was inversely correlated with ALSFRS-R decline (Spearman = -0.45, p = 0.028). Ratios of pAKT/tAKT, a pharmacodynamic marker of rho kinase (ROCK) inhibition, were significantly increased at 24 weeks in plasma (neuron-derived) and CSF EVs. CONCLUSIONS: Oral fasudil is safe and well-tolerated in ALS patients. The reduction in NfL and demonstration of CNS target engagement, supports studying the 180 mg dose in a double-blind placebo-controlled study.