The purpose of the study is to determine the efficacy, safety and pharmacokinetics of SC12267 (4SC-101, 35 mg) in combination with methotrexate in comparison to methotrexate alone in the treatment of patients suffering from Rheumatoid Arthritis.

Main Inclusion Criteria:

• Patients with active RA of functional classes I, II or III according to the criteria of American Rheumatism Association for RA
• DAS28(ESR) ≥ 4.5 (DAS28 formula with 4 variables using ESR)
• Patients who have received weekly doses of MTX (10-25 mg/week) for a minimum of 3 months prior to Day 1 dosing, and who have received a stable MTX dose of 10-25 mg/week without any change in route or change in folic acid supplementation for at least 6 weeks prior to Day 1 dosing
• Patients may receive up to 10 mg/day of oral prednisolone or steroid equivalent. Dose must have been stable for at least 30 days and must not be changed during the washout, screening and treatment periods, unless dictated by tolerability requirements

Main Exclusion Criteria:

• Patients with RA of functional classes IV according to the criteria of American Rheumatism Association for RA

• Patients who have received any of the following treatments must abide by the indicated washout period:

  1. Leflunomide requires a 6 month washout period prior to Day 1 dosing
  2. Oral or injectable gold, azathioprine, penicillamine, anakinra require a 30 day washout period prior to Day 1 dosing
  3. Cyclosporine, abatacept, etanercept, adalimumab, infliximab, and rituximab require a 60 day washout period prior to Day 1 dosing
  4. Cyclophosphamide requires a 180 day washout period prior to Day 1 dosing
  5. Parenteral or intra-articular corticosteroids require a 30 day washout period prior to Day 1 dosing

• Receipt of the following drugs within 4 weeks prior to dosing:

  1. Sulfasalazine
  2. Hydroxychloroquine
  3. Use of corticosteroids > 10 mg/day