Study of LX3305 and Methotrexate in Subjects With Stable Rheumatoid Arthritis

Inclusion Criteria: * Males and females ≥ 18 years old * Must be willing to practice 2 adequate methods of contraception for the duration of the study * Rheumatoid arthritis present for at least 3 months; functional class I, II, or III as defined by ACR criteria * Treatment with methotrexate (7.5 to 25 mg per week) for at least the last 3 months, and currently receiving stable dose methotrexate for at least one month prior to the start of the study * Ability to provide written informed consent Exclusion Criteria: * Women who are pregnant or nursing * History of other current inflammatory arthritis * History of opportunistic infection * History of recurrent infections or current infection 2 weeks prior to start of study * Presence of significant, uncontrolled medical problems * Treatment with any disease-modifying anti-rheumatoid drugs other than methotrexate within 4 weeks prior to start of study * Use of chondroitin sulfate, glucosamine sulfate, minocycline, or matrix metalloproteinase inhibitors, H-2 blockers, proton pump inhibitors, or misoprostol within 4 weeks prior to study start * Receipt of live vaccine within 8 weeks prior to study start * Rheumatoid arthritis, functional class IV as defined by ACR criteria