Phase II study designed to evaluate the safety and efficacy of BIIB057 in Subjects with Rheumatoid Arthritis who have experienced an Inadequate Response to Disease-Modifying Antirheumatic Drugs (DMARDs).

Inclusion Criteria:

• Adult onset RA satisfying 2010 Revised ACR Criteria for the Classification of RA with a disease history of at least 6 months
• Active RA as defined by: at least 4 swollen joints (based on 28-joint count), at least 4 tender joints (based on 28-joint count), and high-sensitivity CRP (hsCRP) 10mg/L or greater
• No prior treatment with biologics
• Receiving a DMARD therapy for at least 3 months, using a regimen that has been stable for at least 28 days prior to screening

Exclusion Criteria:

• History of inflammatory joint disease other than RA
• Abnormal chest X-ray consistent with tuberculosis, malignancy, or infection
• History of malignancy, carcinoma in situ, or high-grade dysplasia
• History of opportunistic infection, infection requiring treatment, serious local infection, recent fever, active herpes zoster or Epstein-Barr virus, or diagnosis or family history of Creutzfeldt-Jakob disease.
• Clinically significant cardiac disease
• Treatment with prednisone >10 mg orally daily
• Intra-articular steroid injection within 28 days before screening
• Clinically significant abnormality in hematology or blood chemistry values at screening