Efficacy Confirmation Trial of CDP870 as add-on Medication to Methotrexate (MTX) in Japanese Rheumatoid Arthritis (RA)

Inclusion Criteria: * Subjects must have a diagnosis of adult-onset RA of at least 6 months but not longer than 15 years in duration as defined by the 1987 American College of Rheumatology classification criteria. * Subjects must have active RA disease as defined by: * At least 9 tender joints and 9 swollen joints * ESR of 30 mm/hour or CRP of 1.5 mg/dL * Subjects must have received treatment with MTX for at least 6 months prior to the start of study drug administration. The dose of MTX must have remain fixed for at least 2 months prior to the study and the dose of MTX should be within 6 to 8 mg/week. Exclusion Criteria: * Patients who have a diagnosis of any other inflammatory arthritis * Patients who have a secondary, non-inflammatory type of arthritis (eg, osteoarthritis, fibromyalgia) * Patients who currently have, or who have a history of, a demyelinating or convulsive disease of the central nervous system (eg, multiple sclerosis, epilepsy) * Patients who have NYHA (New York Heart Association) Class III or IV congestive heart failure * Patients who currently have, or who have a history of, tuberculosis * Patients who have a high risk of infection (with a current infectious disease, a chronic infectious disease, a history of serious infectious disease) * Patients who currently have, or who have a history of, malignancy * Female patients who are breastfeeding or pregnant, who are of childbearing potential * Patients who previously received treatment with 2 or more anti-TNFα drugs or who previously failed to respond to treatment with 1 or more aint-TNFα drugs.