The purpose of the study is to evalute the efficacy, safety and tolerability of rozanolixizumab for treatment of adult participants with myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD).

Inclusion Criteria:

• Participant must be ≥18 to ≤89 years of age, at the time of signing the informed consent
• Confirmed diagnosis of MOGAD consistent with published diagnostic criteria for MOGAD
• Participant has history of relapsing MOGAD with at least 1 documented relapse over the last 12 months and a documented positive serum MOG Ab test using a cell-based assay (CBA) within 6 months prior to randomization
• Participant must be clinically stable at the time of the Screening Visit and during the Screening Period

Exclusion Criteria:

• Participant has been diagnosed with a neurological autoimmune disease (including multiple sclerosis (MS) and aquaporin-4 positive neuromyelitis optica spectrum disorder (NMOSD)), or a systemic autoimmune disease that in the opinion of the investigator can interfere with the safety of the participant
• Participant has a clinically important active infection (including unresolved or not adequately treated infection) as assessed by the investigator, including participants with a serious infection within 6 weeks prior to the first dose of the investigational medicinal product (IMP)
• Participant has a current or medical history of primary immunodeficiency
• Participant tests positive for aquaporin-4 antibodies at Screening
• Participant has a serum total IgG level ≤ 5.5g/L

Data from this trial may be requested by qualified researchers six months after product approval in the US and/or Europe, or global development is discontinued, and 18 months after trial completion. Investigators may request access to anonymized individual patient-level data and redacted trial documents which may include: analysis-ready datasets, study protocol, annotated case report form, statistical analysis plan, dataset specifications, and clinical study report. Prior to use of the data, proposals need to be approved by an independent review panel at www.Vivli.org and a signed data sharing agreement will need to be executed. All documents are available in English only, for a prespecified time, typically 12 months, on a password protected portal. This plan may change if the risk of re-identifying trial participants is determined to be too high after the trial is completed; in this case and to protect participants, individual patient-level data would not be made available.

Data from this trial may be requested by qualified researchers six months after product approval in the US and/or Europe or global development is discontinued, and 18 months after trial completion.

Qualified researchers may request access to anonymized IPD and redacted study documents which may include: raw datasets, analysis-ready datasets, study protocol, blank case report form, annotated case report form, statistical analysis plan, dataset specifications, and clinical study report. Prior to use of the data, proposals need to be approved by an independent review panel at www.Vivli.org and a signed data sharing agreement will need to be executed.All documents are available in English only, for a pre-specified time, typically 12 months, on a password protected portal.

MOG001 consists of a Double-Blind (Part A) and an Open-Label Extension Study Period (Part B).