Longer-term follow-up of nusinersen efficacy and safety in adult patients with spinal muscular atrophy types 2 and 3

•37 adults with SMA 2–3 treated with nusinersen, followed for up to 30 months of treatment.•Median MRC score increased from baseline to visits at 6 and 14 months, not afterwards.•The median rate of MRC score increase was 1.85 points per year.•Revised hammersmith scale median score increased only from baseline to 6 months.•Revised hammersmith scale's calculated annual rate of change was 0 points. The effectiveness of nusinersen treatment in patients with spinal muscular atrophy (SMA) was established in clinical trials only for pediatric patients. Few cohort studies confirmed its benefit in adults up to 22 months of treatment. We report a longer-term observation of nusinersen treatment effects and safety in a large cohort of adult patients. Patients with SMA type 2 and 3 treated with nusinersen at Tel-Aviv Medical Center between March 2018 and September 2020 were prospectively recruited. Neurological impairment, motor, respiratory function, and side effects were recorded. We compared baseline measurements with those after 6, 14, and 26 months of treatment and calculated the annual rates of change. Overall, 37 patients were treated (21–64 years old). 16 completed 26 months, and 8 completed 30 months of treatment. The median score on the Medical Research Council strength scale increased from baseline to visits at 6 and 14 months (p ≤ 0.03), but not afterwards, with a median increase of 1.85 points per year. Revised Hammersmith Scale median score increased only from baseline to 6 months (p = 0.02), with a calculated annual rate of change of 0 points. No significant change was noticed in the respiratory function. The only side effect was post lumbar puncture headache. In conclusion, our study further supports the efficacy and safety of nusinersen treatment in adult patients with SMA2 and SMA3, with modest improvement in muscle strength, and stabilization of motor function over a relatively long period of observation.