Clinical Outcomes in Patients with Spinal Muscular Atrophy Type 1 Treated with Nusinersen

Abstract

Background: Spinal muscular atrophy type 1 (SMA1) is a motor neuron disease associated with progressive muscle weakness, ventilatory failure, and reduced survival. Objective: To report the evaluation of the nusinersen, an antisense oligonucleotide, on the motor function of SMA1. Methods: This was a longitudinal and observational study to assess the outcomes of nusinersen therapy in SMA1 patients using the HINE-2 and CHOP-INTEND scales. Results: Twenty-one SMA1 patients (52.4% males) were included; the mean age at first symptoms was 2.7 months (SD = +/- 1.5), and the mean disease duration at first dose was 34.1 (SD = +/- 36.0) months. During posttreatment, the mean gain on the CHOP-INTEND was 4.9, 5.9, 6.6, and 14 points after 6, 12, 18, and 24 months, respectively. Starting medication with a disease duration of less than 12 months and/or without invasive ventilation were predictors of response on CHOP-INTEND. Of the patients, 28.6% acquired a motor milestone or gained at least three points on the HINE-2. The daily time for ventilatory support was reduced after treatment in most of the patients with noninvasive ventilation at baseline. No change in the daytime use of ventilation was observed in most of the patients using invasive ventilation at baseline. Conclusions: Nusinersen produces improvements in motor and respiratory functions, even in long-term SMA1 patients. However, patients under invasive ventilation at the beginning of the treatment experience little benefit.