Efficacy

Efficacy of Spinraza (Nusinersen) in Treating Spinal Muscular Atrophy

Spinraza (Nusinersen) is an FDA-approved medication specifically designed to treat Spinal Muscular Atrophy (SMA), a rare genetic disorder characterized by loss of motor neurons, leading to muscle weakness and atrophy. The efficacy of Spinraza has been demonstrated in several clinical trials. In the pivotal phase 3 trial ENDEAR, infants with SMA Type 1 treated with Spinraza showed significant improvements in motor milestones compared to those who were not treated. The majority of treated infants achieved head control, rolling abilities, and were able to sit without support for at least 30 seconds, which are milestones rarely achieved in the natural course of the disease.

Long-term studies of Spinraza have also shown sustained benefits in motor function over time. The SHINE study, an open-label extension of earlier trials, reported that individuals with SMA who continued Spinraza treatment maintained or improved motor function scores, highlighting the drug's sustained efficacy. Additionally, Spinraza has been found to reduce the risk of death or permanent ventilation in infants with SMA Type 1, further demonstrating its effectiveness in altering the disease course.

Efficacy of Zolgensma (onasemnogene abeparvovec) in Treating Spinal Muscular Atrophy

Zolgensma (onasemnogene abeparvovec) represents a novel gene therapy approach for the treatment of SMA, specifically for pediatric patients less than 2 years of age who have bi-allelic mutations in the survival motor neuron 1 (SMN1) gene. The efficacy of Zolgensma was established in the START trial, where a one-time intravenous infusion of the therapy led to significant and sustained improvement in motor function in children with SMA Type 1. The majority of treated children achieved milestones such as head control, sitting without support, and some were able to crawl, stand, and walk, feats that are typically unachievable with untreated SMA Type 1.

Further evidence of Zolgensma's efficacy comes from the STR1VE trial, where it demonstrated a survival rate much higher than the natural history of SMA Type 1. Infants treated with Zolgensma also showed rapid and sustained improvement in motor function and milestone achievements. The therapy works by providing a functional copy of the SMN1 gene, which leads to increased production of the SMN protein, essential for motor neuron survival. This gene replacement therapy addresses the genetic root cause of SMA, offering a transformative treatment option for this devastating disease.