Safety of teriflunomide for the management of relapsing-remitting multiple sclerosis.

INTRODUCTION: Teriflunomide is a new oral disease-modifying drug (DMD), recently approved for the first-line treatment of relapsing multiple sclerosis (MS). Since MS is a chronic disease, which often necessitates long-term treatment, data not only on efficacy but also on long-term safety, including pregnancy-related issues, are very important. AREAS COVERED: In this review article, we outline the key preclinical and clinical data on teriflunomide with a focus on its safety profile. We summarize adverse events observed in the Phase II and III clinical trials and the safety data from the long-term extension phases as well as the > 15-year post-marketing experience with the parent drug, leflunomide. We also consider the evidence regarding immune competence and potential fetal risks of the drug. EXPERT OPINION: Teriflunomide has the advantage of a convenient once-daily oral administration scheme and a large body of evidence suggesting a manageable safety profile (clinical development program with > 6800 patient-years of exposure and post-marketing experience with leflunomide). Further post-marketing data, especially regarding pregnancy outcomes and risks of infections, will help to define the exact place of teriflunomide in the treatment of MS in the future, especially compared with the other oral DMDs.