Study Evaluating The Efficacy And Safety Of SBI-087 In Seropositive Subjects With Active Rheumatoid Arthritis

Inclusion Criteria: * Meets the American College of Rheumatology (ACR) 1987 revised criteria for classification of Rheumatoid Arthritis (RA) for at least 6 months prior to screening * Active RA as defined by \>= 5 swollen and \>= 5 tender joints (28-joint count) and at least 1 of the following: C-reactive protein \>= 10 mg/L or Erythrocyte Sedimentation Rate \>= 28 mm/h * Must be seropositive as defined by a documented history of rheumatoid factor (RF) or anti-cyclic citrullinated peptide (anti-CCP) positivity * Must be receiving a stable route and dose of methotrexate (up to 25 mg weekly) Exclusion Criteria: * Any significant health problem other than rheumatoid arthritis * Any clinically significant laboratory abnormalities * Any prior use of B cell-depleting therapy