First Drug to Treat a Form of Multiple Sclerosis

Researchers at the American Academy of Neurology meeting in San Diego reported that an experimental drug originally developed to treat lymphomas has become the first experimental drug ever to show an effect on a form of multiple sclerosis for which there are no approved treatments.

In a clinical trial, Sanofi's tolbrutinib, an experimental oral Bruton's tyrosine kinase inhibitor, was shown to delay the progression of confirmed disability at six months in early-onset, non-relapsing, secondary-progressive MS by 31 percent.

Multiple Sclerosis Treatment

"This is the first clinical trial to show a positive effect in delaying disability progression in secondary-progressive, non-relapsing MS, a late-onset form of the disease in which neurological function gradually deteriorates over time and disability increases relentlessly," said study leader Dr. Robert Fox of the Cleveland Clinic in a statement.

The study report, published in the New England Journal of Medicine, stated that in the trial involving 1,131 patients, the rate of confirmed disability progression after six months was 22.6 percent in the tolbrutinib group compared to 30.7 percent in the placebo group.

Improved Disability

The researchers also reported that more patients who received tolbrutinib achieved improvement in disability, with the confirmed disability improvement rate at six months being 8.6 percent compared to 4.5 percent with placebo.

Marks of disease activity, including inflammation and tissue damage, were also reduced with tolbrutinib compared to placebo.

However, serious side effects, particularly liver complications, are more common with tolbrutinib, which is currently under review for potential approval in the United States.

Key Study Findings

Fox said, "Apparently, one in 200 patients develops a severe elevation in liver enzymes in the first three months of use. Therefore, close monitoring is important, and the drug should be discontinued immediately in patients with elevated liver enzymes."

A second report published in the same journal also stated that two separate studies in patients with relapsing-remitting multiple sclerosis showed that tolbrutinib was no better than teriflunomide, marketed by Sanofi under the brand name Aubagio, in reducing annual relapse rates.