The objectives of this study are to verify the superiority in efficacy (American College of Rheumatology 20%: ACR20) and investigate the pharmacokinetics and safety of CDP870 versus placebo without coadministration of MTX in active RA patients in whom MTX cannot be administrated.

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 6 tender joints and 6 swollen joints
  • ESR of 28 mm/hour or CRP of 2.0 mg/dL

• Subjects who have failed to respond or have been resistant to at least one DMARD (including MTX)

• Subjects in whom MTX cannot be administered for any of the reasons(incomplete response/safety concerns)

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.