Safety and Efficacy Study of BCD-020 in Therapy of Indolent Non-Hodgkin's Lymphoma

Inclusion Criteria: * Having signed a written informed consent; * Patients' age is 18 years or more; * Diagnosis of CD20-positive indolent non-Hodgkin lymphoma of following morphological types:Follicular non-Hodgkin lymphoma stage II-IV according to Ann Arbor, grade I-II;Nodal marginal zone lymphoma stage II-IV according to Ann Arbor; Splenic marginal zone lymphoma. * Life expectancy of not less than 3 months after the enrollment in the study; * Morphological and immunohistochemical examination of the tumor (both lymph node biopsy and bone marrow biopsy) - within 3 months before the enrollment in the study ; * Performance status ≤2 on the ECOG scale; * Hemoglobin \> 80 g/l; leukocyte count ≥ 3.0×109/l but less than 25×109/l, absolute neutrophil count ≥1.5×109/l, platelet count ≥100×109/l; * Presence of at least one measurable lesion; * Patient's ability in the investigator's opinion to comply with the protocol procedures; * Willingness of patients with preserved reproductive function to use reliable contraception methods (at least two contraception methods in women, e.g., spermicide and condom). Exclusion Criteria: * Bulky disease - size of any single lesion more than 10 cm in the greatest diameter; * Secondary transformation to high-grade lymphoma; * Other types of non-Hodgkin lymphomas apart from follicular non-Hodgkin stage II-IV lymphoma according to Ann Arbor, grade 1,2; nodal marginal zone lymphoma stage II-IV according to Ann Arbor; splenic marginal zone lymphoma. * Patients regularly taking corticosteroids during 1 month preceding the enrollment in the study; * Occurrence of other (aside from NHL) diseases that can distort the assessment of the main disease symptoms expression; mask, enhance, modify the main disease symptoms or induce clinical and laboratory-instrumental symptoms similar to the non-Hodgkin lymphomas; Severe resistant hypertension; Decompensated forms of heart (NYHA class ХСН III, IV), liver and kidney disorders (creatinine level \>133 µmol/l, AST, ALT, and bilirubin level 3 times exceeding the norm) except for the cases where the symptom is caused by lymphoma; Decompensated respiratory failure; Tumor infiltration of the lungs; Decompensated diabetes mellitus; Active autoimmune diseases; Ongoing infections requiring antimicrobial therapy. * Usage of the drugs: At any time prior to the enrollment into the study - interferon-based drugs or monoclonal antibodies for the treatment of NHL; Chemotherapy or radiotherapy was completed less than 21 day prior to the enrollment into the study; Vaccination within 1 week prior to the enrollment into the study; * Presence of any psychiatric disorders including major depressive conditions and/or suicidal thoughts in anamnesis that in opinion of the investigator may put a patient at an excessive risk or influence the ability of patients to fulfill the study protocol; * Myocardial infarction less than 1 month before the enrollment into the study; * Severe CNS or PNS dysfunctions; * Drug and alcohol addiction; * Known HIV, HBV, HCV infection, syphilis; * Known primary or secondary immunodeficiency; * Primary CNS lymphoma or metastasis in the CNS; * Known intolerance or allergy to mouse proteins or any components of the study drugs, and also to the premedication drugs; * Pregnancy or lactation; * Prior or concomitant malignances except for adequately treated basal cell carcinoma and in situ cervical cancer; * Any restraints or impossibility to administer the study drug via an intravenous infusion; * Major surgery within 1 week prior to the enrollment into the study; * Simultaneous participation in any other clinical study or any preceding participation in other studies within 3 months prior to enrollment in this study.