A Clinical Trial to Study the Effects of Revamilast in Patients With Rheumatoid Arthritis

Inclusion Criteria: 1. Male or female ≥18 to ≤ 65 years of age 2. Documented history of RA; diagnosed according to the revised American College of Rheumatology criteria (ACR) 3. Active RA defined as patients with: * 6 swollen joint counts * 6 tender/painful joint counts, and * At least two of the three following criteria: * Rheumatoid Factor positive or Anti CCP positive * CRP ≥1.2 times upper limit of normal reference range or ESR \>28 mm/hr * Morning stiffness lasting \>45 min for at least last4 weeks 4. DAS-28 CRP values ≥ 4.5 at screening (visit 1) 5. Patients must have been on stable (15 mg to 25 mg) or maximum tolerated dose of MTX for at least 12 weeks prior to screening 6. The patient's written informed consent to participate in the study 7. Female participants must have a negative serum pregnancy test at screening visit. 8. Males must agree to use barrier while on study medication and for 90 days after taking the last dose of study medication 9. Must meet the following laboratory criteria: * Hemoglobin ≥ 9 g/dL * White blood cell (WBC) count; ≥3.0 X 109/L * Platelet count ≥ 100,000 /L (100 X 109/L) * Serum creatinine \<1.5 mg/dL (or 133mol/L) * Total bilirubin \<2.0 mg/dL * AST \& ALT\<1.5 times upper limit of normal Exclusion Criteria: 1. Diagnosis of RA prior to 16 years of age (Juvenile RA) 2. Non-degenerative joint diseases or other joint diseases that could interfere with the evaluation of RA 3. Patients with any other autoimmune rheumatic disorders with the exception of Sjogren's syndrome. 4. Patients with first degree relative with immune deficiency 5. History of infection with human immunodeficiency virus and/or active hepatitis B or C 6. Severe disabling arthritis leaving the patient eligible for surgical intervention, or incapacitated and prostrated patients 7. Patients with a history of drug or alcohol abuse or chronic smoking 8. Uncontrolled diabetes mellitus 9. Concurrent diseases that might interfere with the conduct of the study, 10. ECG abnormalities judged by the investigator to be clinically significant 11. History of using any other test drug, one month before the beginning of this trial 12. Women who are pregnant or breast-feeding or on hormonal therapy 13. Patients who in the Investigator's opinion might not be suitable for the study. 14. Patients with a life expectancy of less than 1 year