US FDA panel says current data not 'convincing' for Biogen's ALS drug

New Delhi: A panel of advisers to the U.S. health regulator said on Wednesday there was not enough convincing evidence to show the effectiveness of Biogen Inc's experimental treatment for an inherited form of amyotrophic lateral sclerosis (ALS).

The U.S. Food and Drug Administration (FDA) panel voted 5 to 3 that the late-stage data for the drug, tofersen, did not show it was an effective treatment for ALS patients with mutations in a specific gene that leads to accumulation of toxic levels of a protein known as superoxide dismutase 1 (SOD1). One panelist abstained.

"I think it meets the evidentiary standards for accelerated approval but not for full approval," said panelist Robert Alexander, a neurologist who voted with the majority.

If tofersen is approved under the agency's accelerated approval pathway, a confirmatory trial will need to show the drug provides a clinical benefit for it to remain on the market.

"I think there is evidence suggesting potential clinical benefit, but does it cross a convincing line or not? That's a little bit of what I am struggling with," said panelist Michelle Mielke, an expert in neurogenerative diseases.

The panel also discussed whether there was sufficient evidence to show that there was a benefit when tofersen reduced levels of the protein neurofilament in patients. Advisers voted unanimously in favor of the protein-lowering data as reasonably likely to predict that the drug could benefit patients.

In a late-stage study, tofersen failed to meet the main goal of reducing symptoms in patients with fast-progressing ALS, but reduced levels of the protein neurofilament. Neurofilament is considered a potential marker of nerve cell degeneration.

ALS, the cause of which is largely unknown, is also known as Lou Gehrig's disease. The disease results in weakened muscles and causes nerve cells in the brain and spinal cord to break down, affecting physical function and leading to severe disability and death.

Earlier this week, FDA staff reviewers said tofersen's safety risks would not prevent its potential approval.