The US Food and Drug Administration (FDA) has approved a high dose regimen of Spinraza (nusinersen) for the treatment of spinal muscular atrophy (SMA).
SMA is a genetic neuromuscular disorder characterized by the loss of motor neurons, causing progressive muscle weakness and loss of movement due to atrophy. SMA mainly affects the muscles involved in walking, sitting, arm movement, and head control. Breathing and swallowing may also become difficult as the disease progresses. SMA is caused by genetic mutations in the SMN1 gene. Extra copies of the nearby related gene, SMN2, modify the severity of SMA, with type 1 being the most severe and type 4 the least severe.
Nusinersen is an antisense oligonucleotide that modifies SMN2 pre-mRNA splicing. The high dose regimen comprises of a 50 mg/5 mL loading dose and 28 mg/5 mL maintenance dose injections administered intrathecally. Until now, nusinersen was administered at a lower 12 mg dose.
The approval is based on data from the phase 2/3 randomized, controlled, dose-escalating DEVOTE clinical trial evaluating safety, tolerability, pharmacokinetics, and efficacy of high dose nusinersen. The study enrolled a total of 145 patients across ages and SMA types and included an open-label safety evaluation cohort (Part A), a double-blind, active control randomized treatment cohort (Part B; n=99), and an open-label treatment cohort (Part C; n=40) to assess the safety and tolerability of transitioning from the currently approved dose of nusinersen 12 mg to the higher dose regimen.
Results illustrated that treatment-naïve, symptomatic infants who received the high dose regimen of nusinersen experienced statistically significant improvements in motor function measured by the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND).
Additionally, the safety profile of the high dose regimen was generally consistent with the known safety profile of the already approved low dose regimen. The most common adverse reactions included pneumonia, COVID-19, pneumonia aspiration, and malnutrition.
For more information, visit https://www.globenewswire.com/news-release/2026/03/30/3264519/0/en/FDA-Approves-New-High-Dose-Regimen-of-SPINRAZA-nusinersen-for-Spinal-Muscular-Atrophy.html
To learn more about SMA and other rare musculoskeletal conditions, visit https://checkrare.com/diseases/musculoskeletal-diseases/