Gene Therapy for Spinal Muscular Atrophy: Safety and Early Outcomes.

Area of Science:

• Neurology
• Genetics
• Pediatrics

Background:

• Spinal muscular atrophy (SMA) is a leading genetic cause of infant mortality.
• The absence of the SMN1 gene causes SMA.
• Onasemnogene abeparvovec-xioi is an FDA-approved SMN1 gene replacement therapy for SMA.

Purpose of the Study:

• To report safety and early outcomes of onasemnogene abeparvovec-xioi treatment in children with SMA.
• To evaluate the efficacy of gene therapy in a broader age range (1-23 months) than previously studied.

Main Methods:

• Retrospective analysis of safety and efficacy data.
• Treatment of 21 children (age 1-23 months) with onasemnogene abeparvovec-xioi.
• Monitoring of adverse events, liver function tests, and platelet counts.
• Assessment of motor function outcomes.

Main Results:

• Gene transfer was well tolerated in children ≤6 months.
• Older children experienced more frequent, asymptomatic elevations in liver enzymes (AST, ALT, GGT) requiring higher prednisolone doses.
• 90% of children had an asymptomatic drop in platelets that resolved without intervention.
• 89% of assessed children showed improvement in motor function.

Conclusions:

• Onasemnogene abeparvovec-xioi gene therapy is safe and shows early efficacy in children with SMA.
• Thorough screening and careful post-treatment management are crucial for successful outcomes.
• The study supports the use of gene replacement therapy in a wider age range of SMA patients.