Biogen has reported positive interim results of a Phase I/II trial of tofersen being studied to treat amyotrophic lateral sclerosis (ALS) in adults with a confirmed superoxide dismutase 1 (SOD1) mutation.

The antisense oligonucleotide (ASO) Tofersen selectively targets the genetic driver of ALS, a fatal neurodegenerative disease characterised by motor neuron loss in the brain and spinal cord.

Biogen noted that the interim data highlights a statistically significant reduction in SOD1 protein levels and a numerical trend towards slowing of clinical decline in SOD1-ALS patients treated with tofersen.

“We are committed to bringing a potential breakthrough therapy to patients with ALS.”

Biogen research and development executive vice-president Michael Ehlers said: “The interim results of this study, which achieved proof-of-biology and proof-of-concept, support the initiation of Phase III clinical trial to confirm the efficacy and safety of tofersen in SOD1-ALS patients and further demonstrate the potential of ASOs to target the genetic driver of disease.

“We are committed to bringing a potential breakthrough therapy to patients with ALS and we are expediting our efforts with the aim of addressing this urgent unmet need.”

The randomised, placebo-controlled, single and multiple-ascending dose Phase I/II study is evaluating the safety, tolerability, pharmacokinetics, pharmacodynamics and exploratory efficacy endpoints of tofersen in 70 patients with ALS.

Biogen randomised 50 participants with SOD1 mutations in the multiple ascending dose portion of the study. They received tofersen (20mg, 40mg, 60mg, or 100mg) or placebo for a period of 12 weeks.

This March, Biogen dosed the first patient in the Phase III VALOR study of tofersen in adults with ALS with a confirmed SOD1 mutation.