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 µµmol/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.