This is an open-label, uncontrolled, observational study in patients with rheumatoid arthritis (RA) who are receiving tocilizumab concomitantly with methotrexate as part of their standard of care.

This single arm, open label study evaluates the safety and pharmacodynamic profile of tocilizumab in RA patients. Participating patients are among those for whom tocilizumab is indicated and who are scheduled to receive tocilizumab as part of their normal care, in full compliance with the FDA-approved prescribing information. Study assessments consist of clinical evaluations and laboratory tests conducted in conjunction with the first three monthly intravenous infusions of tocilizumab. These assessments are designed to provide a better understanding of the pharmacodynamic effects and mechanistic actions of tocilizumab and help guide the clinical development of other therapeutic agents for RA. A total of 15 patients are expected to participate for approximately 10 weeks.

Inclusion Criteria:

• ≥ 18 years of age
• Moderately to severely active rheumatoid arthritis
• Inadequate response to previous treatment with an anti-TNF agent
• Receiving methotrexate for at least 12 wks before study

Exclusion Criteria:

• Previous treatment with tocilizumab
• Previous treatment with other IL-6 receptor inhibitors
• Treatment with corticosteroids (oral prednisone >10 mg/day or equivalent) within 4 wks
• Conditions noted in the tocilizumab prescribing information

Adult rheumatoid arthritis patients with indication for treatment with tocilizumab.