Comparative Efficacy, Safety and Immunogenicity Study of Etanercept and Enbrel

Inclusion Criteria: * patients of both sexes, from 18 to 75 years old; * body weight \> 45 kg; * patients diagnosed with: rheumatoid arthritis (RA) of moderate and high activity, according to the classification of RA criteria of the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) of 2010; * functional class I, II or III according to the Classification of the Functional Class of the RA of the American College of Rheumatology (ACR); * number of painful joints (NPJ) ≥ 6 (68 joints examined), number of swollen joints (NSJ) ≥6 (66 joints examined); * ESR (Erythrocyte sedimentation rate)≥ 28 mm/hour or СRP (C - reactive protein) \> 7.0 mg/dl; * patient who receive methotrexate for at least 12 weeks at doses of 7.5-20 mg/week (orally or parenterally), and the dose and route of administration of methotrexate was not changed for 4 weeks before randomization; * patient who stopped therapy with other basic antirheumatic drugs, except methotrexate, and completed the wash-out period for these drugs of at least five half-life periods, but not less than 2 weeks (whichever is longer); * if a patient takes NSAIDs (Nonsteroidal anti-inflammatory drugs), the dose of the drug should be stable within 2 weeks before randomization; * if a patient takes oral glucocorticosteroids, the dose should be ≤10 mg/day of prednisolone (or equivalent) and be stable for 2 weeks before randomization; * women of childbearing age and men who have partners, who have agreed to use reliable contraceptive methods during the entire study period and within 3 months after its termination. Reliable methods of contraception include: intrauterine devices, double-barrier method or state after surgical sterilization and vasectomy; * signed informed consent of participants to participate in this study, which was obtained before any screening procedures, including discontinuation of forbidden-drugs. Exclusion Criteria: * known hypersensitivity to Etanercept or other components of the study drugs; * other rheumatic diseases, autoimmune diseases, connective tissue diseases, immunodeficiency (e.g. psoriasis, psoriatic arthritis, primary Sjogren syndrome, systemic lupus erythematosus or demyelinating diseases such as multiple sclerosis); * septic arthritis within 12 months before screening; purulent arthritis of prosthetic joints; * acute or frequent recurrent chronic, local or generalized infections (bacterial/fungal/viral) or sepsis, or history of recurrent infections, or increased risk of developing infections or sepsis; * an active form of tuberculosis; the history of the ineffective treatment of tuberculosis; latent tuberculosis or risk of developing tuberculosis (e.g., contact with patients who have an active form of tuberculosis, shortly before screening); * severe interstitial lung diseases (bronchial asthma, chronic obstructive pulmonary disease, bronchiectasis, fibrosis); * malignant diseases, including history (except successfully treated non-metastatic basal cell or squamous cell skin cancer or cervical cancer); * congestive heart failure of class III or IV, according to New York Heart Association criteria, or unstable angina; * uncontrolled diabetes mellitus, uncontrolled arterial hypertension; * abnormal laboratory parameters at screening: * haemoglobin \< 100.0 g/L; * platelets \< 125 \*10\^9 cell/L; * leukocytes \< 3.5 \*10\^9 cell/L, * absolute neutrophil count \< 1.5 \*10\^9 cell/L; * absolute lymphocyte count \< 0.8 \*10\^9 cell/L; * ASТ (Aspartate aminotransferase), АLТ (Alanine aminotransferase) 3 and more times higher than the upper limit of normal and serum total bilirubin 2 and more times higher than the upper limit of normal; * serum creatinine 2 times or higher than the upper limit of normal; * history of clinically significant or uncontrolled diseases of the respiratory system, liver, kidney, blood, gastrointestinal tract, endocrine system, immune system, skin, nervous system (including demyelinating disorders), cardiovascular system, or history of an autoimmune or mental disorder, or any condition which, in the opinion of the Investigator, can pose a threat to the safety of a patient, affect the study results or prevent a patient from completing the study; * hepatitis В, С; * scheduled surgical intervention including joint replacement during the study; * recent chickenpox; * oral and gastrointestinal ulcers; * pregnancy, breastfeeding; * history of alcohol or drug abuse; * vaccination with live or attenuated vaccines within 4 weeks before the screening, or scheduled vaccination during the study, or within 3 months after the last dose of the study/reference drug; * previous treatment with any other GEBD (genetically engineered biological drugs) (GEBD) for rheumatoid arthritis (including, tocilizumab, adalimumab, anakinra, abatacept, infliximab, rituximab, golimumab, Etanercept, certolizumab) or tofacitinib; * use of systemic or intraarticular corticosteroids, except prednisolone at a dose of≤10 mg/day orally, or equivalent to GCS (Glucocorticosteroids) within 2 weeks before randomization; * use of alkylating agents (e.g. cyclophosphamide, chlorambucil) within 6 months before randomization; * use of intravenous or oral antimicrobial agents 4 weeks before randomization; simultaneous participation in any other clinical study, or participation in a clinical study within 3 months before screening.