WEDNESDAY, April 24, 2019 (HealthDay News) -- Limited evidence suggests that nusinersen treatment provides long-term benefits for children with later-onset spinal muscular atrophy (SMA), according to a study published online April 24 in Neurology.
Basil T. Darras, M.D., from Boston Children's Hospital, and colleagues reported results of intrathecal nusinersen in 28 children with later-onset SMA (11 SMA type II; 17 SMA type III). Children from a phase 1b/2a study who first received nusinersen during that study and were eligible to continue treatment in an extension study were included in analyses. The study was a 253-day, ascending-dose (3, 6, 9, and 12 mg), open-label study that enrolled children aged 2 to 15 years. The extension study was a 715-day, single-dose (12 mg) level study.
The researchers found that by the visit on day 1,150, mean Hammersmith Functional Motor Scale-Expanded (HFMSE) scores, Upper Limb Module (ULM) scores, and 6-Minute Walk Test (6MWT) distances improved (HFMSE: SMA type II, +10.8 points; SMA type III, +1.8 points; ULM: SMA type II, +4.0 points; 6MWT: SMA type III, +92.0 m). The mean compound muscle action potential values remained unchanged. None of the children discontinued nusinersen due to adverse events.
"The current results extend the age range over which motor function improvements have been observed following nusinersen treatment and more than double the length of treatment time over which progressive improvements in motor function have been observed in children with SMA," the authors write.
Several authors disclosed financial ties to pharmaceutical companies, including Ionis Pharmaceuticals and Biogen; Biogen manufactures nusinersen and supported the study.