Inclusion Criteria:

1. Written informed consent for participation in the study; 2. Male and female subjects, 18 to 60 years of age. 3. Diagnosis of relapsing multiple sclerosis (according to 2017 revision to the McDonald Diagnostic Criteria for Multiple Sclerosis); 4. Documentary evidence that, at the time of signing the informed consent, the subject had: 1. at least 1 relapse within the last calendar year (12 months), or. 2. 2 relapses within the last 2 years (24 months), or. 3. at least 1 T1 gadolinium-enhanced brain lesion on MRI and 1 relapse within 2 calendar years (24 months) prior to signing the informed consent; 5. The subject must be neurologically stable for 30 days prior to signing the informed consent. 6. Total EDSS score 0 to 5.5 inclusive. 7. Positive anti-Varicella Zoster IgG antibodies according to screening test results; 8. Absence of suicidal ideation and behavior confirmed at screening according to C-SSRS score within 1 month prior to signing the informed consent. 9. Willingness of both female and male patients and their sexual partners of childbearing potential to use reliable contraception.

Exclusion Criteria:

Primary progressive MS; Duration of multiple sclerosis for more than 10 years with EDSS ≤2.0 according to screening assessments; Other disorders (besides multiple sclerosis), which could affect the assessment of symptom severity for the primary disease A relapse during screening period ; Use of systemic corticosteroids for 30 days prior to signing the informed consent; Disorders, besides multiple sclerosis, requiring long-term systemic therapy with corticosteroids and/or immunosuppressants; Heart failure (NYHA functional class III/IV); encephalopathy, lactic acidosis, MELAS syndrome), neuromyelitis optica, sarcoidosis; Diagnosis of HIV, hepatitis B, hepatitis C, or syphilis ; Increased TTG levels at least two times the upper limit of normal on screening tests; Suicidal ideation and/or behavior History of severe depression Pregnancy, breastfeeding, or intention to become pregnant at any point throughout the study period; Prior use of anti-B cell therapies Intolerance, including hypersensitivity to any component of BCD-132/teriflunomide, premedication drugs, or conditions in which the above drugs are contraindicated in the Investigator's opinion; History of severe allergic or anaphylactic reactions to humanized and/or murine monoclonal antibodies; History of progressive multifocal leukoencephalopathy Known alcohol or drug addiction or signs of current alcohol/drug addiction Inability to follow the procedures specified in the Protocol, as assessed by the Investigator; Contraindications to MRI and administration of gadolinium-based contrast agents: Any current or prior malignancies, except for successfully treated basal cell carcinoma and cervical carcinoma in situ Vaccination within 6 weeks prior to signing the informed consent. -

Clinical study No. BCD-132-4/MIRANTIBUS is an international, multicenter, randomized, double-blind, double-masked study using an active reference drug (teriflunomide). The goal of the study is to evaluate the efficacy and safety of BCD-132 in the treatment of patients with relapsing multiple sclerosis. The study includes adults with relapsing-remitting multiple sclerosis (according to 2017 revision to the McDonald Diagnostic Criteria for Multiple Sclerosis) and EDSS disability score up to 5.5. Some of the subjects in this study will be patients rolled over from ongoing phase II clinical study No. BCD-132-2; treatment group, individual product kit number (IPKN), stratification factors, order of procedures and timeframes for blinded therapy with a duration of up to 100 weeks will remain the same.

Arms

Experimental: BCD-132

IV infusion every 24 weeks in combination with daily placebo tablets. The total duration of the blinded therapy is 100 weeks (a total of 5 treatment cycles with BCD-132 in combination with the daily placebo tablets)

Active Comparator: Teriflunomide, 14 mg orally

Teriflunomide, 14 mg orally daily, in combination with intravenous placebo infusions. The total duration of the blinded therapy is 100 weeks (a total of 5 treatment cycles with intravenous placebo infusions in combination with daily teriflunomide tablets).

Interventions

Biological: - BCD-132

anti-CD20 monoclonal antibody

Drug: - Teriflunomide

Teriflunomide 14 mg