Children treated with single-dose gene replacement therapy (Zolgensma; Avexis, Bannockburn, IL) for spinal muscular atrophy (SMA) continue meeting development milestones in the phase 3 SPR1NT clinical trial (NCT03505099). Treatment was administered intravenously to presymptomatic children with genetically confirmed SMA intravenously when they were age 6 weeks or less.
The SPR1NT trial showed age‑appropriate major milestone gains with treatment, and prolonged event-free survival in patients with SMA Type 1. At the last follow up assessment, participants mean age was 6.6 months for a cohort of 10 children and 4.6 months for a cohort of 12 individuals. Of those who had a 6-month swallow evaluation, all had normal swallow function and were fed exclusively by mouth. Of the 22 patients being evaluated overall, all were alive and none required permanent ventilation.
All participants in the cohort of 10 children achieved or maintained a Children's Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) score of more than 50; 7 had a score 60 or more and 5 had the maximum score of 64.
Of those in the cohort of 10 children, 6 were able to sit without support for at least 30 seconds at an average age of 7.6 months. Of those children, 3 (30%) were able to stand with assistance at an average age of 10.1 months.
"These updated data reinforce what we have seen in other Zolgensma studies, including survival of children with SMA Type 1 who would have in the past died or required permanent ventilation before the age of 2," said Eugenio Mercuri, MD, PhD, Department of Pediatric Neurology, Catholic University. "We are seeing further robust evidence of the potential of gene therapy to effectively halt motor neuron loss, help patients achieve motor milestones and alter the course of SMA with a 1-time treatment."