Operetta III

Treatment tested

• Ocrelizumab

  B-lymphocyte antigen CD20 binding agent

Other measures (12)

Inclusion Criteria: * Children and adolescents from 10 years to less than 18 years of age, at the time of baseline visit * Body weight ≥25 kg * Diagnosis of RRMS in accordance with the International Pediatric Multiple Sclerosis Study Group (IPMSSG) criteria for pediatric MS, Version 2012, or McDonald criteria 2017 or 2024 * Neurologic stability for at least 30 days prior to screening, and between screening and baseline * Expanded Disability Status Scale (EDSS) score, 0-5.5, at screening * Must have received all childhood required vaccinations as per local/national recommendations for childhood vaccination against infectious diseases Exclusion Criteria: * Participants who are positive for aquaporin 4 (AQP4) or myelin oligodendrocyte glycoprotein (MOG) antibody are not eligible to participate in the study * Any known presence or suspicion of other neurologic disorders that may mimic multiple sclerosis (MS) * Any known or suspected active infection at screening or baseline (except nailbed infections), or any major episode of infection requiring hospitalization or treatment with IV anti-infective agents within 4 weeks prior to baseline visit or oral anti-infective agents within 2 weeks prior to baseline visit * History or known presence of recurrent or chronic infection (e.g., human immunodeficiency virus [HIV], syphilis, tuberculosis [TB]) * Contraindications against SC injections or other conditions not suitable for SC injections, e.g., extremely thin SC fat layer * History of a severe allergic or anaphylactic reaction to humanized or murine monoclonal antibody or known hypersensitivity to any component of ocrelizumab solution * Contraindications to mandatory premedications (i.e., corticosteroids and histamines), including closed-angle glaucoma for antihistamines * Participants who have previously received treatment with B cell-targeted therapies, including ocrelizumab * Any previous treatment with cyclophosphamide, alemtuzumab, anti-CD4, cladribine, mitoxantrone, daclizumab, laquinimod, total body irradiation, or bone marrow transplantation * Treatment with any investigational agent within 24 weeks of screening or 5 half-lives, whichever is longer (or longer if indicated by the PD action of the drug)

The main purpose of this study is to evaluate the pharmacokinetics (PK) of ocrelizumab administered subcutaneously (SC) in children and adolescents aged 10 to \<18 years with RRMS. The study consists of a 48-week treatment period, an Optional Ocrelizumab Extension (OOE) period of at least 48 weeks, and Safety Follow-up (SFU) for 104 weeks.