Dose-Response Study of Ocrelizumab for Rheumatoid Arthritis.

INTERVENTION: Intervention name : Ocrelizumab Dosage And administration of the intervention : 50mg,200mg,500mg twice as an IV infusion on Days1 and 15 Control intervention name : Placebo Dosage And administration of the control intervention : administered twice as an IV infusion on Days1 and 15 CONDITION: Rheumatoid Arthritis PRIMARY OUTCOME: Percentage of patients with ACR20 response at week 24. INCLUSION CRITERIA: ‐ Diagnosis of RA for >=6 months according to the revised 1987 ACR criteria for the classification of RA. ‐ Receiving methotrexate at a dose of 6 to 8 mg/week(oral) for >=12 weeks, with a stable dose for the last 4 weeks before treatment. ‐ Positive serum RF.