An Exploratory Phase 2, Randomized, Double-blind, Multicenter Study To Assess The Effects Of Tofacitinib (Cp-690,550) On Magnetic Resonance Imaging Endpoints, In Methotrexate Naive Subjects With Early Active Rheumatoid Arthritis

Evaluation of efficacy and safety of tofacitinib (CP-690,550) for the treatment of early rheumatoid arthritis in adult patients with moderate to severe disease who are methotrexate naïve. The efficacy will be evaluated by exploring the effects on joint structure assessed by magnetic resonance imaging, x-rays and by standard clinical assessment.