Open-label Study to Assess the Safety and Efficacy of CDP6038 in Patients Who Completed RA0056

Inclusion Criteria:

• Subject completed the RA0056 study (Week 12 Visit)
• Subject must have maintained their stable dose (and route) of methotrexate (MTX) between 12.5 to 25mg/week in RA0056, and plan to maintain this same dose and route of administration for at least 12 weeks
• Female subjects must be either postmenopausal for at least 1 year, surgically incapable of childbearing, or effectively practicing an acceptable method of contraception (either oral/parenteral/implantable hormonal contraceptives, intrauterine device, or barrier and spermicide). Abstinence is not considered an acceptable method of contraception for this study
• Female subjects of childbearing potential must agree to use 2 methods of adequate contraception during the study and for 6 months (24 weeks) after their last CDP6038 dose
• Male subjects must agree to ensure that they or their female partner(s) use adequate contraception during the study and for 12 weeks after the subject receives their last dose of CDP6038

Exclusion Criteria:

• Subject has an ongoing serious adverse event from the RA0056 study
• Female subject of childbearing potential has a positive pregnancy test or plans to become pregnant during the study or within 6 months (24 weeks) following their last dose of study medication
• Subject has evidence of active or latent tuberculosis
• Subject is receiving any biologic response modifier or synthetic disease-modifying antirheumatic drug other than MTX
• Subject has an alcohol consumption of more than 1 unit per weekday. One unit equals 1 glass of beer or lager (~330mL), a glass of wine (125mL), or a measure of spirits/hard liquor (25mL)
• Subject with any other condition in RA0056 (eg, clinically significant laboratory values, frequent adverse events) which in the Investigator's or Sponsor's judgment would make the subject unsuitable for inclusion in the study