Nusinersen: a Single-Center Real-Life Experience in Type 1 Spinal Muscular Atrophy

Background: Nusinersen, an antisense oligonucleotide designed to treat 5q-Spinal Muscular Atrophy (SMA), is currently available in Portugal for SMA patients. In clinical trials, SMA type 1 patients achieved a substantial motor milestone response.

Objective: To report the clinical results of nusinersen in a single tertiary centre, in Portugal.

Methods: We performed a retrospective study of type 1 SMA patients treated with nusinersen. Demographic, clinical (including motor scores – CHOP-INTEND), ventilation and feeding parameters were obtained from clinical records.

Results: We are currently treating 5 genetically confirmed SMA type 1 patients – current mean age 16,4 months (range 8–25 months), four with 2 copies of SMN2 and one with 3 copies of SMN2. The mean time from the first symptoms to the diagnosis confirmation was 3,1 months (range 0,3-10,0) and from the diagnosis confirmation to the beginning of treatment was 1,1 months (range 0,5-1,7). Only 3 patients had ≥ 6 months of treatment (5, 6 and 9 administrations of nusinersen respectively), and they all improved at least 4 points in CHOP-INTEND score (mean change 10.0 points). The eldest patient (25 months-old) began treatment at 2,3 months and has achieved independent sitting. Prior to treatment, 2 patients required continued non-invasive ventilation (NIV) and one 14 hours per day. After 6 months of treatment they all reduced time of NIV up to 8 hours per day. Gastrostomy was performed in 2 patients during treatment and one required tube feeding. No side effects of treatment were noticed.

Conclusion: We observed an improvement in motor function and ventilatory support in SMA type 1 patients with ≥ 6 months of treatment with nusinersen. Despite our small sample, our findings are promising and contribute to the increasing evidence that early diagnosis and treatment is paramount for these patients.