Spinal muscular atrophy (SMA) is a neurodegenerative disorder that results in ongoing loss of motor function loss in the absence of disease-modifying therapies (DMT). Previous studies have demonstrated the short-term benefits of DMT on the natural progression of SMA. This analysis aims to explore the long-term impact of Nusinersen on adults with SMA.
This retrospective study included a cohort of patients aged >18 years with genetically confirmed SMA who were treated at a single MDA Care Center treated with Nusinersen for up to five years. The study analyzed the data from 45 patients assessing outcomes using Hammersmith Functional Motor Scale Expanded (HFMSE), Revised Upper Limb Module (RULM), Forced Vital Capacity (FVC), and patient-reported fatigue scale. These measures were recorded during regular follow-up intervals to evaluate longitudinal responses to DMT. The duration of treatment varied between patients.
A linear mixed model was employed to analyze patient characteristics including the SMN2 gene copy number and age at the start of treatment. The data revealed baseline functional scores were significantly correlated with the number of copies of the SMN2 gene and contributed to outcome variability among patients. HFMSE and RULM scores showed no statistically significant difference compared to baseline but indicated an upward trend in functional outcomes. The patient-reported fatigue scale demonstrated a reduction in fatigue levels over time, although this was not statistically significant. There was no statistically significant difference in response to treatment based on baseline characteristics such as age and severity of SMA.
In conclusion, this study aligns with previously reported findings and suggests that long-term DMT with Nusinersen offers sustained clinical benefits in adults with SMA. These findings provide additional evidence supporting the initiation of DMT in patients across different ages and severities of SMA.