A Comparative Study of Pharmacokinetics, Pharmacodynamics, Safety, and Immunogenicity of RPH-035 and Ocrevus® in Patients With Relapsing-remitting or Secondary Progressive Multiple Sclerosis With Exacerbations

This study is a multicentre, double-blind, randomised, comparative Phase I study

The clinical study includes the following periods:

1. Screening period: days \[-27…-0\] (up to 1st administration of study therapy) 2. Main period: weeks \[1-49\]

Patients who meet the eligibility criteria shall be randomised in a 1: 1 ratio to one of two study arms: RPH-035 and Ocrevus®

During the Main Period, the patients will receive their first infusion of ocrelizumab (RPH-035 or Ocrevus®) at a dose of 300 mg, followed by another 300 mg of the drug product after 2 weeks. The duration of ocrelizumab administration will be 2.5 hours ± 15 minutes. The third infusion at a dose of 600 mg should be administered 6 months after the first infusion of the initial dose. The administration is scheduled for the "Week 25" visit.

The Main Period includes regular collection of data on complaints and symptoms, physical examination, assessment of vital signs (measurement of body temperature, blood pressure (BP), pulse), body weight measurement, monitoring of laboratory parameters (clinical and biochemical blood tests, measurement of the concentration of immunoglobulin type G (IgG), general urine analysis), IG analysis, electrocardiogram (ECG), magnetic resonance imaging (MRI) at weeks 9, 17, 25, 49, neurological examination, assessment according to the Expanded Disability Status Scale (EDSS), registration of adverse events/serious adverse events (AEs/SAEs). MRI and assessment of response to therapy within the Main Period will be performed approximately once every 8 weeks during the first six months of the study (week 1 - week 25), then at week 49

The week 49 visit consists of two stages: prior to drug administration, procedures are performed to assess the safety and effectiveness of the blinded therapy. After receiving and analysing the results, the research physician decides whether to terminate or extend therapy. If therapy needs to be continued, the patient is transferred to the follow-up period 3. After-Therapy period: weeks \[49-97\]

During the After-Therapy Period, beginning at week 49, all patients will receive RPH-035 therapy, including those who received Ocrevus® therapy during the Main Period. Visits are also included in this period, which are conducted in the form of telephone contacts to assess the patient's well-being, collect data on concomitant therapy and possible AEs