Observational Study of Patients Treated with Teriflunomide

The study is a two-year prospective observational study of patients treated with teriflunomide. The investigators will recruit up to 75 patients at baseline, based on the estimate that approximately 20% of these patients (~ 15 patients) will have evidence of disease activity at the end of the first year of treatment with teriflunomide, as determined by clinical evaluation (relapses) and MRI activity (new T2 hyperintense lesions). The investigators will assess the expression of a putative biomarker signature consisting of toll like receptor 2(TLR2), TLR4 and chemokine receptor 1 (CCR1) on CD4 T-subsets at baseline and at intervals on treatment with teriflunomide to determine whether expression of this biomarker signature on one or more CD4 T-subsets correlates with disease activity.