Nusinersen improves walking distance and reduces fatigue in later‐onset spinal muscular atrophy

INTRODUCTION: Ambulatory individuals with spinal muscular atrophy (SMA) experience muscle weakness, gait impairments, and fatigue that affect their walking ability. Improvements have been observed in motor function in children treated with nusinersen, but its impact on fatigue has not been studied. METHODS: Post hoc analyses were used to examine changes in 6‐minute walk test (6MWT) distance and fatigue in children and adolescents with SMA type II and III who received their first dose of nusinersen in the phase Ib/IIa, open‐label CS2 study and were ambulatory during CS2 or the extension study, CS12. RESULTS: Fourteen children performed the 6MWT. Median (25th, 75th percentile) distance walked increased over time by 98.0 (62.0, 135.0) meters at day 1050, whereas median fatigue changed by −3.8% (−19.7%, 1.4%). DISCUSSION: These results support previous studies demonstrating clinically meaningful effects of nusinersen on motor function in children and adolescents with later‐onset SMA.