A Study To Evaluate The Mechanism Of Action Of CP-690,550 In Patients With Rheumatoid Arthritis

Inclusion Criteria:

• Subject must have a diagnosis of rheumatoid arthritis based on the American College of Rheumatology Association

• The subject has active disease at both Screening and Baseline, as defined:

  • ≥4 joints tender or painful on motion, AND
  • ≥4 joints swollen;
• The subject must have at least one knee, one elbow, one wrist or two metacarpophalangeal joints with active synovitis suitable for biopsy by the shaver technique

Exclusion Criteria:

• No arthroscopy should have been performed in the past 3 months in the same joint that is to be biopsied in this study.
• No intra-articular steroids should have been injected in the joint to be biopsied in this study in the previous 3 months.
• Subjects with evidence of hematopoietic disorders or evidence of hemoglobin levels < 9.0 gm/dL or hematocrit < 30 % at screening visit or within the 3 months prior to baseline synovial biopsy.
• An absolute white blood cell (WBC) count of < 3.0 x 109/L (<3000/mm3) or absolute neutrophil count of <1.2 X 109/L (<1200/mm3) at screening visit or within the 3 months prior to baseline synovial biopsy.
• Thrombocytopenia, as defined by a platelet count <100 x 109/L (< 100,000/mm3) at screening visit or within the 3 months prior to baseline synovial biopsy.
• Estimated GFR less than 40 ml/min based on Cockcroft Gault calculation .