Nusinersen, a disease-modifying treatment, positively affects motor function for individuals with spinal muscular atrophy (SMA) regardless of age, disease severity, or disease type (type 1, 2, or 3) at the time of treatment initiation, according to real-world data published in Neuromuscular Disorders.
The clinical trials leading to the approval of nusinersen focused on children with SMA types 1 and 2; therefore, these researchers studied disease outcomes in all 3 SMA types in patients of all ages from infant to adult.
The investigators analyzed real-world outcomes of 44 patients with SMA treated with nusinersen in Switzerland for a duration from 6 up to 42 months. They obtained outcome data from the Swiss Registry for Neuromuscular Disorders covering the time from the start of nusinersen administration for all SMA types in Switzerland in April 2018 until August 2020.
The researchers analyzed outcome data measured by standardized clinical motor function assessments. They used the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders and the Hammersmith Infant Neurological Examination for patients with SMA younger than 2 years and for all patients unable to sit independently.
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Depending on the motor capabilities of older patients, the investigators analyzed the scores from the Revised Upper Limb Module and either the standard or expanded versions of the Hammersmith Functional Motor Scales. For patients able to walk, the researchers used the 6-Minute Walk Test to assess motor function.
All 11 patients with SMA type 1 improved their motor functions. Eight of 21 patients with SMA type 2 gained between 1 and 5 motor skills, while 3 of 12 patients with SMA type 3 gained between 2 and 4 motor skills. Eleven of the 16 individuals with SMA type 2 who had 3 SMN2 copy numbers demonstrated disease stabilization, indicating a therapeutic benefit.
“The therapeutic effect was most striking in type 1 patients who were treated before the age of 18 months. However, the older patients with longer disease duration and less severe phenotypes also showed some positive effects on motor function,” the authors said. “We did not see a correlation between motor response and the need for ventilatory or feeding support.”
Tscherter A, Rüsch CT, Baumann D, et al. Evaluation of real-life outcome data of patients with spinal muscular atrophy treated with nusinersen in Switzerland. Neuromuscul Disord. Published online February 9, 2022. doi:10.1016/j.nmd.2022.02.001