A Dose-range Study of the Safety and Efficacy of Treatment in Adult Rheumatoid Arthritis Patients With an Inadequate Response to Methotrexate

In Part A approximately 120 randomized patients will be treated with either 60 mg AP1189, 80 mg AP1189, 100 mg AP1189 or placebo once daily for 4 weeks as add-on treatment to stable MTX treatment. Part A will conclude with an unblinded assessment for risk/benefit and a recommendation for dose selection for Part B. In Part B patients will be randomized into groups of equal size evaluating 2-3 doses of AP1189 versus placebo. All doses will be administered once daily for 12 weeks as add-on treatment to stable MTX treatment. The proposed sample size per dose group/placebo group is 75 patients, by which the total study population of Part B may be either 225 or 300 patients, depending on the number of dose groups of AP1189 selected for evaluation based on Part A.