Nusinersen (Spinraza®), the first approved disease-modifying therapy for children with spinal muscular atrophy (SMA), significantly improved neurological scores in patients of all ages, according to new findings from a study published in Pediatrics International. However, this treatment demonstrated the potential to alter the disease’s natural course by improving respiratory outcomes only when initiated early.

Pulmonary complications due to respiratory muscle weakness pose the leading cause of morbidity and mortality in infants with SMA type 1 (SMA1). Therefore, a team of researchers from Marmara University School of Medicine in Istanbul, Turkey conducted a study between September 2017 and July 2020 to analyze neurological and respiratory outcomes of 52 patients with SMA1 who received nusinersen treatment for at least 180 days.

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Depending on the age of treatment onset, the researchers divided the patients into 2 groups—19 patients who initiated nusinersen treatment at 6 months or younger and 33 patients who initiated nusinersen treatment after 6 months. Patients received intrathecal injections of nusinersen on days 1 (baseline), 15, 29, and 60 followed by a maintenance dose on day 180.

After 180 days, 46 of the patients still lived with an equal number of deaths in both groups. Over half (52.6%) of the remaining children in the younger cohort still breathed spontaneously or used only noninvasive ventilatory support compared with 24.2% of the children in the older cohort (P =.03). The remaining children all required invasive mechanical ventilation.

Neurological motor function scores as measured by the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders improved significantly for all children, increasing from a median score of 18 at baseline to a median score of 31 on day 180. Patients in the younger cohort exhibited higher scores than those in the older cohort (P =.01).

“The effect of nusinersen on respiratory outcome was detected only in younger patients when nusinersen was started before six months of age,” the authors said. “This finding suggests that prompt and earliest possible intervention after the genetic diagnosis would be ideal for SMA1 patients.”

Reference

Ergenekon AP, Yilmaz Yegit C, Cenk M, et al. Respiratory outcome of SMA type 1 patients treated with Nusinersen. Pediat Int. Published online February 24, 2022. doi:10.1111/ped.15175