Participants who are capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the Informed Consent Form and in this protocol.
Participants who are aged ≥ 12 years at the time of signing Informed Consent Form.
For adolescent participants: Informed Consent Form for study participation signed by the parents or a legal guardian, and assent obtained, as per local requirements.
Confirmed diagnosis of MOGAD meeting the following criteria:
Documented history of ≥ 2 MOGAD attacks (first attack and at least 1 relapse) manifesting with the following presentations/syndromes: optic neuritis;
Transverse myelitis;
ADEM;
Other brain, brainstem, or cerebellar syndrome compatible with demyelination; and any combination of the above.
Diagnosis of MOGAD attacks based on the new or worsening, acute neurologic symptoms with an objective change on neurologic and/or ophthalmologic examination (clinical signs or MRI findings in the corresponding CNS regions [i.e., optic nerve, spinal cord, brainstem, cerebellum and/or brain] or both) that persisted for more than 24 hours, AND
Serum positivity for MOG-IgG by a CBA, AND
Exclusion of alternative diagnoses, including MS.
Confirmed serum positivity for MOG-IgG at screening as assessed by a central laboratory.
Body weight ≥ 20kg at screening.
EDSS score of 0-6.5 at screening.
BCVA better than 20/800 in both eyes at screening.
History of ≥ 1 MOGAD relapse in the 12 months prior to screening or ≥ 2 attacks (may include the first attack) in the 24 months prior to screening.
A relapse is defined as a new clinical episode (new or worsening, acute symptoms and clinical signs, which may be accompanied by MRI evidence of acute demyelination) appearing at least 30 days (90 days if the last attack was ADEM) after the last attack.
Participants receiving either no ongoing chronic IST for MOGAD at the time of screening or receiving ongoing treatment with AZA, MMF, OCS or a combination of AZA or MMF and OCS prior to screening as defined below:
AZA or MMF: treatment for at least 6 months and a dose that has been stable for ≥ 4 weeks prior to screening;
OCS for relapse prevention: treatment with up to 20 mg prednisone equivalent/day at screening.
OCS taper after a MOGAD relapse: treatment with 15-20 mg prednisone equivalent/day one week prior to randomization.
Participants entering the study on a stable dose of AZA or MMF alone or in combination with OCS must have experienced at least one MOGAD attack prior to screening while using AZA or MMF for 3 months.
No contraindications to corticosteroids and at least one of the two other rescue treatments (IVIg or PLEX).
No contraindications to MRI (e.g., hypersensitivity to Gd-containing MRI contrast agents, implanted pacemakers, defibrillators, or other metallic objects on or inside the body that limit performing MRI scans).
For women of childbearing potential: participants who agree to remain abstinent (refrain from heterosexual intercourse) or use adequate contraception during the treatment period and for at least 3 months after the final dose of satralizumab.
A woman is considered to be of childbearing potential if she is postmenarchal, has not reached a postmenopausal state (≥ 12 continuous months of amenorrhea with no identified cause other than menopause, confirmed by a follicle-stimulating hormone level > 40 mIU/mL unless the participant is receiving menopausal hormone therapy), and is not permanently infertile due to surgery (i.e., removal of ovaries, fallopian tubes, and/or uterus) or another cause as determined by the investigator (e.g., Müllerian agenesis).
The definition of childbearing potential may be adapted for alignment with local guidelines or regulations.
IVIg within 4 weeks prior to screening.
PLEX within 4 weeks prior to screening.
OCS, AZA or MMF within 4 weeks prior to screening (if not continued as baseline/background IST in the study).
Tacrolimus or cyclosporine within 6 weeks prior to screening.
B-cell depleting agents, including RTX and ocrelizumab, within 6 months prior to baseline.
Methotrexate within 3 months prior to screening.
Neonatal Fc receptor antagonists within 6 months prior to screening.
IV cyclophosphamide within 6 months prior to screening.
Complement inhibitors (e.g., eculizumab) within 6 months prior to screening.
Glatiramer acetate and IFN-β within 1 month prior to screening.
Fumarates (fumaric acid esters) within 2 months prior to screening.
Teriflunomide within 2 years prior to screening, unless the serum/plasma concentration of teriflunomide is < 0.020 µg/mL (< 20 ng/mL) prior to screening as a result of an accelerated elimination procedure for teriflunomide with cholestyramine or activated charcoal as per local prescribing information.
Other MS disease-modifying treatments, including natalizumab and S1P receptor modulators (e.g., fingolimod, siponimod, ozanimod), within 6 months prior to screening.
IL-6 inhibitory therapy (e.g., tocilizumab) at any time.
Total body irradiation, bone marrow transplantation, and autologous hematopoietic stem cell transplantation at any time.
T-cell depleting agents, including but not limited to alemtuzumab, at any time.
Anti-B-lymphocyte stimulator monoclonal antibody (e.g., belimumab) at any time.
Cladribine, mitoxantrone, or oral cyclophosphamide at any time.
Treatment with any investigational agent within 24 weeks or 5 drug-elimination half-lives of the investigational drug prior to screening (whichever is longer).
Participants who meet any of the following criteria related to the use of previous or concomitant therapies will be excluded from the study:
Participants who are pregnant or breastfeeding, or intending to become pregnant during the study or within 3 months after the final dose of satralizumab;
Women of childbearing potential must have a negative serum pregnancy test result at screening and negative urine dipstick pregnancy test prior to initiation of study treatment.
Participants who have any surgical procedure (except for minor surgeries defined as procedures requiring only local anesthesia or conscious sedation and are done on an ambulatory/outpatient basis; e.g., toenail surgery, mole surgical excision, tooth extraction) within 4 weeks prior to baseline.
Participants who are planning to have surgical procedure (except minor surgeries) during the study.
Participants with active or presence of recurrent bacterial, viral, fungal, mycobacterial infection, or other infection (excluding fungal infection of nail beds or dental caries) at baseline.
Infection requiring treatment with IV anti-infective agents within 4 weeks prior to baseline.
Evidence of progressive multifocal leukoencephalopathy.
Participants with evidence of latent or active tuberculosis (TB), excluding participants receiving chemoprophylaxis for latent TB infection.
If a participant is positive for latent TB, then the participant must be treated with appropriate anti-mycobacterial therapy for at least 4 weeks prior to initiating study treatment administration.
Participants with positive screening tests for hepatitis B (defined as either of the following):
Participants with positive screening test for hepatitis C (defined as positive hepatitis C virus [HCV] antibody and detectable HCV RNA).
Participants with positive HCV antibody but undetectable HCV RNA 12 weeks after HCV treatment completion are eligible to participate in the study.
Participants with congenital or acquired immunodeficiency, including HIV infection.
Receipt of live or live attenuated vaccine within 6 weeks prior to baseline.
History of diverticulitis or concurrent severe gastrointestinal (GI) disorders (such as symptomatic diverticulosis) that, in the investigator’s opinion, may lead to increased risk of complications such as GI perforation.
History of blood donation (1 unit or more), plasma donation or platelet donation within 90 days prior to screening.
History of malignancy within the last 5 years prior to baseline, including solid tumors, hematologic malignancies and in situ carcinoma (except basal cell and squamous cell carcinomas of the skin, or in situ carcinoma of the cervix uteri that have been completely excised and cured).
History of severe allergic reaction to a biologic agent (e.g., shock, anaphylactic reactions).
History of drug or alcohol abuse within 1 year prior to baseline.
Active suicidal ideation within 6 months prior to screening or history of suicide attempt within 3 years prior to screening.
Participants who have had any serious medical condition or abnormality in clinical laboratory tests that, in the investigator's judgment, precludes an individual's safe participation in and completion of the study.