Azathioprine in MOGAD

Prior treatment

• Any live vaccine in the past 3 months or planned during the RCT and RCT+6months
• Necessary use of a xanthine oxidase inhibitor (Allopurinol, Oxipurinol, Thiopurinol, Febuxotat,…)
• Necessary use of angiotensin-converting-enzyme inhibitor, cotrimoxazole, cimetidine and indometacine
• Necessary use of any another immunosuppressive therapy, different than azathioprine, or steroids
• Necessary use of cytotoxic therapy
• Current enrollment or a plan to enroll in any interventional clinical study in which an investigational treatment or approved therapy is use within 5 half-lives prior to baseline. Participation in a non- interventional study can be allowed as long as this participation does not interfere with this protocol or is not likely to affect the subject's ability to comply with the protocol.
• For subjects coming back from strongyloidiasis endemic regions, a parasitology screening examination will be performed on faeces, and that appropriate treatment will be performed prior to administration of corticosteroids

Other illness

• Hypersensitivity to azathioprine or steroids
• Active infections or cancer (including tuberculosis, hepatitis, herpes and VZV)
• Unable to complete an MRI (e.g. due to pacemaker, severe claustrophobia, hypersensitivity to contrast media, or who lack adequate peripheral venous access)
• Necessary use of any other medical illness or disability that, in the opinion of the investigator, would compromise effective trial participation
• Patients with Lesch Nyhan syndrome

Lab values

• Seriously impaired bone marrow functions: Lymphocyte count \< 1000/ml and or Polynuclear neutrophil count \< 1500/ml
• Seriously impaired hepatic functions: ALT and/or AST \> 3N
• Seriously impaired renal functions: GFR \< 29 ml/min/1.73m²

Other

• Psychosis not controlled by treatment
• Thiopurine methyltransferase (TPMT) phenotype deficient or intermediate, with enzymatic activity \< 16 nmol/h/ml
• Necessary use of an aminosalicylate derivates
• Asian patients (probable mutation of the gene NUDT1)
• Female subjects who have a positive a positive urinary or blood pregnancy test result, are pregnant or are currently breast feeding
• Inability to comply with study requirements
• Person under legal protection or deprived of liberty

• Age ≥ 18 years
• First attack of documented acute demyelinating syndrome of the central nervous system, within the past 3 months, whatever the severity or the clinical phenotype
• Tested positive for MOG-Ab, confirmed in a centralized lab (Lyon referral centre)
• Ability of the subject to understand the purpose and risks of the study and provide signed and dated written informed consent.
• Patients should be beneficiary of health care coverage under the social security system
• Female patients of childbearing potential should have effective contraception throughout the course of treatment and for at least three months after stopping treatment.