Study of Tocilizumab in Combination With Methotrexate for Treatment of Moderate to Severe Rheumatoid Arthritis Patients

Inclusion Criteria: * Patients diagnosed with history of moderate-to- severe rheumatoid arthritis for more than 6 months according to the American College of Rheumatology (ACR) 1987 revised criteria for the classification of RA. * Patients who failed to achieve clinical response to treatment of at least 2 DMARDs(disease modifying anti-rheumatic drug) (including MTX) for at least 12 weeks within 12 months prior to screening, of which MTX must have been at a stable dose of 10-20 mg/wk for at least 12 weeks prior to screening. All other DMARDs should be given at standard therapeutic dose. * Patients who satisfy swollen joint count (SJC) ≥ 6 (66 joint count) and tender joint count (TJC) ≥ 8 (68 joint count) at screening and baseline. * C-reactive protein (CRP) level ≥ 1 mg/dl or an erythrocyte sedimentation rate (ESR) ≥ 28 mm/hour at screening and at baseline. Exclusion Criteria: * Patients who have received a major surgery including joint surgery 8 weeks prior to the screening or are scheduled to be operated within 6 months after the enrolment. * Patients with rheumatoid autoimmune disease other than RA, including but not limited to SLE(system lupus erythematosus), or significant systemic involvement secondary to RA. * Patients who belong to the Class IV of the ACR classification criteria for functional status of RA. (ACR Amended Criteria for the Classification of Functional Capacity in Rheumatoid Arthritis; Class IV: Largely or wholly incapacitated with patient bedridden or confined to wheel chair, permitting little or no self-care). * Patients with a history of hypersensitivity to human, humanized or murine monoclonal antibodies or patients with contraindication for them. * Patients who currently have or have a history of recurrence of bacterial, viral,fungal, or mycobacterial infections or other infectious diseases; tuberculosis(TB),atypical mycobacterial disease, clinically significant granulomatous disease on chest radiograph, hepatitis B, hepatitis C, or herpes zoster and etc. However, a patient with hand \& foot fungal infections can participate.