An Open Label Study of the Effects and Safety of Zanubrutinib in NMOSDs Adult Patients

Inclusion Criteria: * Patients must meet the NMOSD diagnostic criteria set by the international NMO Diagnostic Group (IPND) in 2015. * Serum AQP4-IgG positive. * Clinical evidence of at least 2 documented relapse (including first attack) in the last 2 years, with at least 1 relapse within 12 months prior to screening. * Extended Disability Status Scale (EDSS) score ≤7.5 at screening. * Age 18 to 75 years inclusive, weight at least 35 kg at the time of informed consent. * If the patients were using the following baseline treatment for relapse prevention, they must be treated at a steady dose for at least 4 weeks prior to enrollment: * Azathioprine, metecophenol ester and other immunosuppressive agents * Oral corticosteroid (≦30mg/ day prednisone tablet or equivalent dose of other hormones) * (patients or their legal representatives) can provide written informed consent indicating that they understand and agree to comply with the requirements of the study protocol. Exclusion Criteria: * Continuous treatment with strong or moderate CYP3A inhibitors or inducers is required during the study period. Patients were excluded if they had taken a potent or moderate CYP3A inhibitor or inducer within 7 days prior to administration of the study drug (or had stopped taking these drugs for less than 5 half-lives). * Previously treated with BTK inhibitors (e.g., ibrutinib). * Allergic to the study drug or any of the ingredient. * Desease relaps (including first episode) within the previous 30 days. * Pregnancy or lactation. * Previous or current malignancy, except locally recurrent cancers that have received radical treatment (e.g. excised basal or squamous cell skin cancer, cervical or breast cancer in situ). * Currently central nervous system (CNS) disease that may affect the evaluation of NMOSD. * Serious and uncontrolled conditions considered by the investigator that could affect safety, compliance and endpoint evaluation, or need for use of a drug not permitted in the protocol. * Disease that could affected drug absorption, distribution, metabolism, and excretion determined by the investigator. * Any major clinical infection lead to hospitalization or parenteral antibiotic treatment within 1 month prior to screening; Or other infections that may be aggravated due to the study determined by the investigator. * Active, latent or undertreated mycobacterium tuberculosis (TB) infection * Known primary immunodeficiency or underlying disease such as human immunodeficiency virus (HIV) infection. * Hepatitis B or C virus infection by serological test. * Received B-cell targeted therapy (e.g. Rituximab) within 6 months prior to the initial administration of the study drug. * Received biologics such as tozizumab within 12 weeks prior to initial administration of the study drug. * Received live attenuated vaccine during the screening and study periods, or any live virus vaccine within 8 weeks prior to initial administration. * Abnormal and clinically significant in ECG examination during screening. * Uncontrolled hypertension (SBP\>160 mmHg or DBP ≥ 95 mmHg) * Grade 3 or 4 heart Failure, (NYHA scale). * Severe liver insufficiency (Child-pugh C). * Aspartate aminotransferase (AST)\>3 times the upper limit of normal (ULN) and/or alanine aminotransferase (ALT)\>3ULN and/or bilirubin \>2ULN. * Estimated creatinine clearance \<30 mL/min or requiring dialysis. * Inability to receive MRI scans * A history of clinically significant CNS trauma * Received experimental drug or other experimental treatment within 4 weeks prior to screening or during 5 pharmacokinetic half-lives or duration of biological effects, whichever is longer. * Participate in another clinical study. * Accept any of the following: * BCG vaccination within 1 year prior to screening. * Prior bone marrow transplant, hematopoietic stem cell transplant, or systemic radiation therapy. * Received intravenous gamma globulin within 30 days prior to screening. * Plasmapheresis or leukocyte separation within 90 days prior to screening * Abnormal white blood cell count, neutrophil count, lymphocyte count, or platelet count during the screening and were considered unsuitable for study by investigator * Inability to swallow capsules or medical conditions that significantly affect gastrointestinal function * A history of severe hemorrhagic disorders such as hemophilia A, hemophilia B, von willebrand disease, or a history of spontaneous bleeding requiring blood transfusion or other medical intervention. * History of stroke or intracranial hemorrhage within 6 months prior to screening * Current alcohol, drug or chemical abuse, or history of such abuse within 1 year prior to screening. * Anticoagulants or a combination of anticoagulants and antiplatelet agents is ongoing or planned. * Any other circumstances in which the investigator or sponsor considers the patient unsuitable for study participation.