A Study In Neuromyelitis Optica Spectrum Disorder (NMOSD) With Satralizumab As An Intervention

Inclusion criteria

• Age 18 to 74 years, inclusive, at the time of informed consent

• Have a diagnosis of AQP4 antibody seropositive NMOSD according to the International Panel for NMO Diagnosis (IPND) criteria

• For women of childbearing potential: agreement to either remain abstinent (refrain from heterosexual intercourse) or to use reliable means of contraception (physical barrier [patient or partner] in conjunction with a spermicidal product, contraceptive pill, patch, injectables, intrauterine device or intrauterine system) during the treatment period and for at least 3 months after the last dose of study drug Cohort 1 (treatment-naïve NMOSD patients)

• Confirmation of NMOSD diagnosis with AQP4+ antibodies

• Have clinical evidence of at least 1 documented attack or relapse (including first attack) in the last year prior to screening

• Naive to maintenance therapy (disease-modifying therapy [DMT] or immunosuppressive therapy [IST]) Cohort 2 (NMOSD patients with inadequate response to RTX [or its biosimilar])

• Confirmation of NMOSD diagnosis and AQP4+ antibodies in the disease history of the patient

• Have a length of disease duration from first symptom of ≤5 years

• History of ongoing treatment with RTX (or its biosimilar) (at least 2 infusions) for NMOSD with a maximum duration of 6 months since last administration prior to enrolment in the study

• Ongoing disease activity after last RTX (or its biosimilar) infusion i.e., relapse and/or any new inflammatory event, confirmed by magnetic resonance imaging (MRI) or ophthalmological assessment

Exclusion criteria Exclusion criteria for both the cohorts

• Inability to complete an MRI

• Participants who are pregnant or breastfeeding, or intending to become pregnant during the study or within 3 months after the final dose of satralizumab

• Any surgical procedure (except for minor surgeries) within 4 weeks prior to baseline

• Evidence of other demyelinating disease, including MS or progressive multifocal leukoencephalopathy (PML)

• Evidence of serious uncontrolled concomitant diseases that may preclude patient participation

• Active or presence of recurrent bacterial, viral, fungal, mycobacterial infection or other infection (excluding fungal infections of nail beds or caries dentium) at baseline

• Infection requiring hospitalization or treatment with intravenous (IV) anti-infective agents within 4 weeks prior to baseline visit

• Evidence of chronic active hepatitis B

• Evidence of active tuberculosis (TB)

• History or laboratory evidence of coagulation disorders

• Receipt of a live or live-attenuated vaccine within 6 weeks prior to baseline

• Presence or history of malignancy

• History of drug or alcohol abuse within 1 year prior to baseline

• History of diverticulitis that, in the Investigator's opinion, may lead to increased risk of complications such as lower gastrointestinal perforation

• History of severe allergic reaction to a biologic agent

• Active suicidal ideation within 6 months prior to screening, or history of suicide attempt within 3 years prior to screening

• Treatment with any investigational agent within 6 months prior to baseline or 5 drug elimination half-lives of the investigational agent (whichever is longer) Cohort 1 (treatment-naïve NMOSD patients)

• Any previous treatment with IL-6 inhibitory therapy (e.g., tocilizumab), alemtuzumab, total body irradiation, stem-cell therapy, or bone marrow transplantation

• Any previous treatment with eculizumab, belimumab, natalizumab, glatiramer acetate, fingolimod, teriflunomide, dimethyl fumarate, siponimod, or ozanimod

• Any previous treatment with anti-CD4, cladribine or mitoxantrone

• Any previous treatment with B-cell depleting agents

• Any previous treatment with immunosuppressants Cohort 2 (NMOSD patients with inadequate response to RTX)

• Discontinued RTX (or biosimilar) treatment due to any other reason than inadequate response to treatment