Long-term efficacy of nusinersen and its evaluation in adolescent and adult patients with spinal muscular atrophy types 1 and 2

The efficacy of nusinersen and its evaluation in patients with spinal muscular atrophy (SMA) has been established in clinical trials only for pediatric patients, not for adolescent and adult patients who developed SMA in infancy or early childhood. We report a long-term follow-up in adolescent and adult patients with SMA types 1 and 2. Nusinersen-treated patients with SMA types 1 and 2 between 2017 and 2022 were retrospectively reviewed. We compared baseline motor function tests with those after the final treatment. Physical and occupational therapists performed Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND), Hammersmith Functional Motor Scale-Expanded (HFMSE), and Revised Upper Limb Module (RULM). The Landau and Galant reflexes were not performed in CHOP-INTEND. Meaningful improvement was defined as CHOP-INTEND, 4; HFSME, 3; and RULM, 2. Seven patients with SMA (type 1, 1; type 2, 6) with a median age of 23 (range, 12–40)years were treated with nusinersen for 3.55 (1.78–4.53)years. Improvement was detected in CHOP-INTEND (pre, 5 [0–31]; post, 21 [0–39]; difference, 5 [0–26]; p = 0.100) without significance, although not in HFMSE (pre, 0 [0–3]; post, 0 [0–5]; difference, 0 [0–2]; p = 0.346) and RULM (pre, 1 [0–20]; post, 3 [0–21]; difference, 1 [0–2]; p = 0.089). Owing to prolonged treatment intervals with the COVID-19 pandemic, RULM worsened in two patients. Nusinersen was effective in long-term follow-up. Only CHOP-INTEND showed meaningful improvement. The interval between doses of nusinersen should not be prolonged even with the COVID-19 pandemic.