A Study of the Safety and Pharmacokinetics of PRO283698 in Patients With Rheumatoid Arthritis

Inclusion Criteria: * RA diagnosed according to the American College of Rheumatology (ACR) Exclusion Criteria: * Female patients who are pregnant, plan to become pregnant during the study, or are breastfeeding * Clinically significant abnormal ECG * History of anaphylactic reactions * Positive hepatitis C antibody or hepatitis B surface antigen * Positive serology for human immunodeficiency virus (HIV) by quantitative polymerase chain reaction * A history of an autoimmune disease other than RA (other than secondary Sjogren syndrome) * Significant systemic involvement of RA, including vasculitis, pulmonary fibrosis, or Felty syndrome * Malignancy, or prior malignancy, other than non-melanoma skin cancer, or cervical carcinoma in situ that has been resected * Recent administration of a live, attenuated vaccine, or anticipation that such a live attenuated vaccine will be required during the study or within 60 days after the last dose * Concomitant therapy with a biologic agent * Recent exposure to any investigational agent * Any current or recent signs or symptoms of infection requiring parenteral antibiotic administration * Hospitalization for a clinically relevant event within the 4 weeks prior to screening