A Study of the Efficacy and Safety of BCD-281 in Patients With Relapsing-Remitting Multiple Sclerosis

Inclusion Criteria: * Provided written ICF to participate in the study. * Male and female subjects aged 18 to 55 years inclusive at the time of signing the ICF. * Diagnosis of multiple sclerosis, established in accordance with the McDonald criteria for the diagnosis of multiple sclerosis (2017 revision). * Relapsing-remitting multiple sclerosis. * The total EDSS score 0-5.5 inclusive. * Documentary evidence of the following at the time of signing the ICF: 1. at least one relapse within the last12 months, and/or 2. 2 relapses within the last 24 months, and/or 3. at least 1 T1 Gd+ lesion detected on brain MRI and 1 relapse within 24 months prior to signing the ICF. * Presence of IgG antibodies to the Varicella-Zoster virus. * Neurological stability for 30 days prior to signing the ICF. * Subject's willingness to discontinue previously prescribed DMTs from the day of the first administration of the IP and throughout the study. * The ability of the subject to follow the Protocol procedures, according to the Investigator. * Willingness of subjects of both sexes and their sexual partners of childbearing potential to use reliable methods of contraception from the time of signing ICF, throughout the study and for 5 months after the last dose of the drug in this study. Exclusion Criteria: * Primary progressive or secondary progressive MS. * MS duration of more than 10 years with EDSS score of ≤2.0 at screening. * Malignant form of MS. * Other medical conditions that can affect the assessment of clinical picture of the MS. * Inability to obtain high-quality MRI images and/or the presence of contraindications to MRI and the administration of gadolinium-containing contrast agents. * Any comorbidities requiring treatment with systemic glucocorticoids and/or immunosuppressive drugs for the duration of the study, with the exception of MS. * History of progressive multifocal leukoencephalopathy. * Any acute or exacerbated chronic infections detected during screening that may have a negative impact on subject's safety during the study therapy. * Concomitant diseases and/or conditions that may affect the assessment of the clinical picture of the underlying disease and/or significantly increase the risk of AEs during the study. * Known alcohol or drug addiction, or current signs of alcohol/drug addiction. * History of severe depression and/or a Beck Depression Inventory score of ≥16 at screening examination. * History of a malignant disease within 5 years prior to screening. * A diagnosis of HIV infection, hepatitis B or C . * Inability to provide the subject with venous access. * Pregnancy or breastfeeding, pregnancy planning and oocyte donation throughout the study and for 5 months after the last dose of ocrelizumab. * A history of severe allergic or anaphylactic reactions to humanized and/or murine monoclonal antibodies. * A history of using any prohibited medications or treatments defined in the study protocol. * Abnormal laboratory blood values, as specified in the study protocol.