Study of Safety and Efficacy of BCD-020 Comparing to MabThera in Patients With Rheumatoid Arthritis

Inclusion Criteria: * Having signed a written informed consent form. * Patients must be from 18 to 80 years of age (both ages inclusive) * Rheumatoid arthritis confirmed according to ACR 1987 criteria. * Seropositive rheumatoid arthritis. * Active rheumatoid arthritis during the last 3 months. * Disease score according to DAS28 of 3.2 or more, TJC≥8 (68), SJC≥8 (66), hsCRP≥6 mg/l, ESR≥28 mm/hr (by Westergren) at the moment of screening. * Patient's functional status - class I-III according to ACR classification * Inadequate response to DMARDs that include one or more TNF inhibitors, intolerance or contraindications to TNF inhibitors. * Necessity of methotrexate treatment during the last 4 weeks prior to screening period with stable/consistent dosage of 7.5 - 20 mg per week. * Patient's ability (in Investigator's opinion) to follow the protocol procedures; * Willingness to use contraception during all study period. Exclusion Criteria: * Patients with Felty's syndrome (irrespectively to clinical form). * Patient's functional status - class IV according to ACR classification . * Rheumatoid arthritis low activity (less than 3.2 according to DAS28). * Concomitant therapy: * Previous treatment with any biological drug products causing CD20+ lymphocyte depletion, including biological investigational drugs. * Treatment with azathioprine within 28 days before the study initiation and with leflunomide within 8 weeks before the study's principal phase (treatment with rituximab). * Intra-articular glucocorticosteroids within 4 weeks before the study's principal phase (treatment with rituximab). * Necessity for prednisone or its equivalent administration at dose more than 10 mg per day. * Necessity for prednisone or its equivalent administration at dose ≤10 mg per day in cases when this dose wasn't stable/consistent during last 4 weeks. * Necessity for administration of non-steroidal anti-inflammatory drugs for arthritis treatment in cases when its doses were not stable/consistent during last 4 weeks. * Pregnancy and breast-feeding. * Changes of laboratory values: * Hemoglobin level is less than 100 g/l; * Leucocyte level is less than 3,0×10e9/l; * Absolute neutrophil count is less than 1,5×10e9/l; * Thrombocyte level is less than 100×10e9/l. * Confirmed chicken pox within 30 days before inclusion to the screening. * Confirmed herpes zoster infection. * Acute forms of any infectious diseases, history of chronic infections with severe clinical manifestations. * Active tuberculosis, history of latent tuberculosis. * Inflammatory disease of the joints (present or in anamnesis) not related to rheumatoid arthritis (including gout, reactive arthritis, psoriatic arthritis, seronegative spondyloarthropathy, Lyme disease and others) or other systemic autoimmune disease (including systemic lupus erythematosus, Crohn's disease, ulcerative colitis, systemic scleroderma, inflammatory myopathy, mixed forms of connective tissue inflammatory diseases, cross-syndrome and others). * Juvenile idiopathic arthritis or juvenile rheumatoid arthritis and/or rheumatoid arthritis developed before the age of 16. * Any determined immunodeficiency. * Pernicious anemia. * Confirmed cobalamine deficiency. * Other somatic diseases (apart from rheumatoid arthritis) that can increase the probability of adverse events during the study or can influence the estimation of symptom manifestation of RA ; mask, enhance or alter the symptoms of RA or cause clinical or laboratory symptoms similar to that of RA; * Positive results of serological test of Hepatitis B surface antigen (HbsAg) or presence of Hbc IgM together with positive results of HBV PCR test, presence of antibodies to Hepatitis C virus, syphilis or HIV. * Major surgery within 28 days prior to the trial principal phase (treatment with rituximab). * Any mental disorder, including major depression and/or suicidal thoughts in anamnesis that can, in Investigator's opinion, create a risk for the patient or influence the patient's ability to follow the study protocol. * Unstable angina pectoris. * Myocardial infarction within less than 1 year prior to participation in the study. * Severe central or peripheral nervous system diseases. * Drug addiction, alcoholism. * Known hypersensitivity to murine proteins or any other components of the medications used in the treatment, methotrexate, folic acid and any drugs used in premedication. * Presence of malignant neoplasm, with the exception of adequately treated basal cell carcinoma and cervical carcinoma in situ and any malignancy with complete remission of more than 5 years; * Simultaneous participation in any other clinical trial, as well as former participation in other clinical trials within 3 months before this study initiation; previous participation in this study.