The objective of this study is to investigate the efficacy and safety of the humanized anti-human IL-6 receptor monoclonal antibody tocilizumab (TCZ) either in monotherapy or in combination therapy with methotrexate (MTX) in patients with an inadequate response to treatment with MTX.

Furthermore, in patients who have been able to achieve control of disease activity via the above therapy, we investigate the possibility of stopping TCZ and verify safety when TCZ is restarted after disease recurrence.

In this study, we aim to prospectively and randomly evaluate efficacy for changes in clinical remission and joint destruction in RA patients in treatment with TCZ monotherapy(SWITCH) and in combination therapy with MTX(ADD-ON), and also to investigate the best therapeutic approach to achieve discontinuation.

Inclusion Criteria:

• Diagnosed with RA in accordance with the 1987 classification criteria of ACR
• Aged 20 to 75 years inclusive at enrolment (within 2 weeks before starting treatment with the investigational drug)
• Treated with MTX at ≥6 mg/week for at least 8 weeks immediately before enrolment
• Rheumatoid arthritis of duration ≤10 years
• DAS28-ESR ≥3.2 (within 2 weeks before starting treatment with the investigational drug)
• Having received and thoroughly understood an adequate explanation about participation in the study, patients who have personally and voluntarily provided written informed consent

Major exclusion criteria:

• Patients who were Steinbrocker Class IV.
• Patients who received leflunomide within 12 weeks, DMARDs other than MTX within 8 weeks , or tacrolimus within 4 weeks before the 1st TCZ infusion.
• Patients who previously received biologic DMARDs including TCZ.