A Phase III Study to Evaluate the Efficacy and Safety of ENIA11 in Combination With Methotrexate Versus Methotrexate Alone in Patients With RA

Inclusion Criteria: 1. Male or female patients aged ≥ 20 years old; 2. Patient meet ACR criteria for rheumatoid arthritis over 6 month duration; 3. Patient with active disease at the time of screening as defined by six or more swollen joints and six or more tender joints; 4. Presence of at least one of the following criteria: * Erythrocyte Sedimentation Rate (ESR) ≥ 28 mm/h, * C-Reactive Protein (CRP) ≥ 10 mg/L, 5. RA functional class I, II, or III; 6. Patients have been treated on methotrexate for at least 3 month, and maintained at stable dose of 15-25 mg/week for at least 8 weeks; MTX low dose as 10 mg per week is allowed for patients who had a documented history of constitutional symptoms at higher doses. 7. Patient is willing and able to comply with study procedures and sign informed consent. Exclusion Criteria: 1. Active autoimmune disease (other than RA) requiring immunosuppressive therapy; 2. In the opinion of the investigator, the patient shows persistent signs of immunosuppression; 3. Known hypersensitivity to etanercept or ENIA11 or any of its components; 4. Previous unsuccessful treatment with etanercept, anti-TNF monoclonal antibodies or a soluble TNF receptor (e.g., infliximab); 5. Suspected or diagnosed pulmonary tuberculosis, or other chronic or current infectious disease at discretion of investigator; 6. Patients who have a history or evidence of a medical condition that would expose them to an undue risk of a significant adverse event during the course of the trial, including but not limited to hepatic, renal, respiratory, cardiovascular, endocrine, immune, neurological, hematological, gastrointestinal or psychiatric disease as determined by the clinical judgment of the investigator; 7. Patients with any of the following laboratory abnormalities: ALT/AST \> 3 times ULN, creatinine \> 2 mg/dl, WBC \< 3,000/mm3, Hgb \< 8.5 g/dL, platelet count \< 100,000/mm3; 8. Patients have received live attenuated vaccination program within 3 months or BCG vaccine within 12 months prior enrollment; 9. Female patient of childbearing potential who: * is lactating; or * has positive urine pregnancy test at Visit 1; or * refuse to adopt reliable method of contraception during the study; 10. Diagnosis of primary fibromyalgia or other joint inflammatory disease including but not limited to gout, reactive arthritis, psoriatic arthritis, seronegative spondyloarthropathy, Lyme disease; 11. Known or suspected positive serology for human immunodeficiency, hepatitis B or C virus; 12. Patient has received any investigational agent within 28 days or 5 half-lives, whichever is longer, prior to the first dose of investigational product; 13. Patient has history of substance abuse, drug addiction or alcoholism; 14. Patient who have had participated in prior phase I/II clinical trial.