The purpose of this study is to determine if PLA-695 changes the blood concentrations of methotrexate when administered together.

Inclusion Criteria:

• Men or women of nonchildbearing potential with rheumatoid arthritis (RA), aged 18 to 75 years
• RA disease onset after 16 years of age and has had the disease for at least 6 months
• Must be receiving a stable, well-tolerated oral dose of methotrexate (5 to 25 mg) taken once weekly for at least 3 months

Exclusion Criteria:

• Evidence of unstable clinically significant disease