Scientists at the Washington University School of Medicine in St. Louis have reported that Biogen’s investigational drug, tofersen, lowered molecular signs of a rare kind of amyotrophic lateral sclerosis (ALS) in a Phase III clinical trial. 

Biogen sponsored the trial, which was led by Washington University researchers.

It was carried out at 32 sites in ten countries and enrolled 108 ALS patients with superoxide dismutase 1 (SOD1) mutations. 

Findings also showed that the drug prevented neurodegeneration. At six months, tofersen did not offer improvement in motor control and muscle strength.

The team further noted that the continued usage of the therapy could stabilise muscle strength and control.

In addition, the drug lowered SOD1 and neurofilament light protein levels in the trial. 

On concluding the placebo-controlled portion of the trial, 95 subjects received tofersen in an open-label extension. 

A substantial difference between the early and late starters in motor function was observed in an interim assessment conducted six months into the extension.

Following one year of treatment, some subjects showed to have muscle strength and control stabilisation.

An antisense oligonucleotide, tofersen is a DNA-based molecule. It can hinder SOD1 protein production.

In July this year, the US Food and Drug Administration accepted the new drug application submitted by Biogen for tofersen to treat ALS linked to SOD1 mutations.

Washington University David Clayson professor of Neurology and trial principal investigator Timothy Miller said: “We see clear evidence that the drug slows down the initiating factor, a SOD1 mutation, as well as the neurodegenerative disease process. 

“The vast majority of people living with ALS experience a relentlessly progressive downhill course, so the stabilisation of function during the open-label extension is truly remarkable.”

In October last year, Biogen reported that tofersen failed to meet the primary goal in the Phase III VALOR trial in SOD1 ALS patients.