 - Receipt of immune-suppressing drugs other than Rheumatrex methotrexate or Soriatane acetretin within 4 weeks prior to the first dose of study drug. Medications you would not be allowed to take during this study include for example, Cytoxan cyclosporine, Imuran azathioprine, or Sulfazine sulfasalazine. If you remain on Rheumatrex methotrexate 25 mgweek or Soriatane acitretin 50 mgday, you must be considered to have inadequate disease control in the opinion of the investigator based on physicians global assessment. You must have been on a stable dose of systemic treatment for at least 1 month prior to the start of the study medication. You will be required to maintain a stable dose of the systemic treatment throughout the study. 