Long-Term Tofersen in SOD1 Amyotrophic Lateral Sclerosis

Area of Science:

• Neurology
• Genetics
• Pharmacology

Background:

• Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease.
• Approximately 2% of ALS cases are linked to mutations in the superoxide dismutase 1 (SOD1) gene.
• Tofersen is an antisense oligonucleotide therapy targeting SOD1 protein synthesis.

Purpose of the Study:

• To evaluate the long-term efficacy and safety of tofersen in adults with SOD1-ALS.
• To compare outcomes between early and delayed initiation of tofersen treatment.
• To assess the impact of tofersen on clinical function, neurodegeneration, and survival.

Main Methods:

• Phase 3 randomized, double-blind, placebo-controlled VALOR trial and its open-label extension (OLE).
• 108 adults with SOD1-ALS were randomized to tofersen or placebo.
• Integrated analysis compared early vs. delayed tofersen initiation over extended follow-up periods.

Main Results:

• Earlier tofersen initiation was associated with numerically less decline in clinical function, respiratory function, muscle strength, and quality of life.
• Tofersen treatment prolonged survival compared to the expected natural history of SOD1-ALS.
• Adverse events were generally consistent with ALS progression; serious neurological events were reversible.

Conclusions:

• Final data demonstrate the clinical benefit of tofersen in SOD1-ALS.
• Tofersen provides a clear rationale for its use in patients with SOD1 gene variants.
• Long-term treatment with tofersen shows sustained efficacy and an acceptable safety profile.