The oral drug teriflunomide reduces relapse rates, disability progression and MRI disease activity in patients with relapsing multiple sclerosis (MS), according to the results of a randomized, double-blind, placebo-controlled trial.

Teriflunomide, a reversible inhibitor of the mitochondrial enzyme dihydroorotate dehydrogenase, is one of several orally administered drugs that are currently being trialed in MS. The new phase III study, known as the TEMSO (Teriflunomide Multiple Sclerosis Oral) trial, builds on encouraging results from an earlier phase II study.

In the TEMSO trial, 1,088 patients with MS were randomly assigned to receive a daily dose of 7 mg or 14 mg of teriflunomide, or placebo, for 108 weeks. Both doses were associated with significant reductions in annualized relapse rates and inflammatory lesion activity compared with placebo. In addition, disability progression was significantly attenuated in the group receiving the higher dose.

Frequencies of serious adverse events were comparable between the three study groups, and the teriflunomide-specific adverse events—diarrhea, nausea and hair-thinning—were generally mild.

“This study is part of a large program for development of teriflunomide,” explains lead investigator Paul O'Connor from the University of Toronto, Canada. “The hope is to get the drug approved for the treatment of relapsing MS—it certainly seems to be effective and safe.”