Open-Label Study to Assess Effects and Safety of Salanersen (BIIB115) Delivered Intrathecally in Presymptomatic Infants With Genetically Diagnosed Spinal Muscular Atrophy

What this Trial Is About

Researchers are investigating how salanersen (BIIB115) affects movement and safety in babies genetically diagnosed with spinal muscular atrophy (SMA) who have not yet shown symptoms. SMA usually results from changes in the SMN1 gene that reduce SMN protein levels, leading to muscle and motor neuron problems. Salanersen aims to increase SMN protein production by helping the related SMN2 gene. The study focuses on babies with 2 or 3 copies of the SMN2 gene, as higher copies usually mean milder SMA symptoms. Participants in this open-label study will receive salanersen through intrathecal injections into the fluid around the brain and spinal cord. The study has two parts: Part 1 includes two doses given about 12 months apart over up to 25 months, and Part 2 includes up to three doses spaced 12 months apart over up to 36 months. All participants receive the study drug, and no placebo is used. During the study, participants will have multiple clinic visits and phone calls for monitoring. Researchers will assess motor skills using tests like WHO motor milestones and measure salanersen levels in cerebrospinal fluid and blood. They will also monitor for any health problems or adverse events. The main goal is to see if early treatment can prevent or reduce SMA symptoms and improve movement abilities over time, with follow-up lasting several years.

A Study to Learn About Salanersen's (BIIB115) Effects on Movement and Its Safety When Given Before Symptoms Appear in Babies With Genetically Diagnosed Spinal Muscular Atrophy (SMA)