Nusinersen (Spinraza®) appears to have long-term efficacy in the treatment of spinal muscular atrophy (SMA), but prolongation in dosing intervals could have a negative impact, according to a recently published study in Brain and Development.

Nusinersen is an antisense oligonucleotide that increases the production of full-length SMN protein by alteration of the SMN2 pre-mRNA splicing process. Although it has been successfully used to improve motor function in young children, its long-term efficacy remains unknown, as there is a lack of data on its usage in adolescents and adults. 

Therefore, the authors aimed to report on a long-term follow-up in adults and adolescents with SMA that received treatment with nusinersen. Due to the COVID-19 pandemic, 5 patients had 27 to 160 days in between scheduled doses. 

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“On January 2020, the World Health Organization declared the coronavirus disease (COVID-19) pandemic and nusinersen-provider centers had to postpone planned infusions of nusinersen,” the authors wrote.

The retrospective, single-center, observational study included 7 patients. Their mean age was 23 years, and the median duration of treatment was 30 months. All of the patients used a wheelchair and 3 needed noninvasive ventilation.

Researchers used the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) and the Revised Upper Limb Module (RULM) to evaluate changes in motor function before and after treatment. Significant improvement was defined as a 4-point increase in CHOP-INTEND and a 2-point increase in RULM. The Wilcoxon signed-rank test was used to analyze numerical variables.

Results revealed there was a significant improvement in motor function according to CHOP-INTEND and RULM. Although RULM transiently decreased in 2 patients that underwent transient dosing intervals due to the pandemic, there were no CHOP-INTEND changes in those patients.

“In conclusion, nusinersen was effective in long-term follow-up in adolescent and adult patients with SMA types 1 and 2; CHOP-INTEND was able to detect the improvement with nusinersen in those patients,” the authors concluded.


Iwayama H, Kawahara K, Takagi M, et al. Long-term efficacy of nusinersen and its evaluation in adolescent and adult patients with spinal muscular atrophy types 1 and 2. Brain Dev. Published online November 2, 2022. doi:10.1016/j.braindev.2022.10.006