A Prospective, One-arm and Open Clinical Study of Obinutuzumab in the Treatment of Pediatric Primary Immune Thrombocytopenia (ITP)

Inclusion Criteria: Age 12-18 years old, male or female Conform to the diagnostic criteria of persistent or chronic immune Thrombocytopenia (ITP) With a platelet count of <30 X 10^9/L measured within 2 days prior to administration（Platelet counts were measured at least 2 times during screening (at least 1 week apart) with platelets<30 X 10^9/L） Failure or recurrence of previous hormonal therapy or hormone dependence The previous emergency treatment of ITP (e.g. methylprednisolone, platelet transfusion, IVIG transfusion) must be completed at least 2 weeks before the first administration Signed and dated written informed consent With Liver and kidney function<1.5×upper limit of normal， such as ALT、AST，BUN，Cre，etc. ECOG physical state score ≤ 2 points Cardiac function of the New York Society of Cardiac Function ≤ 2 Patients receiving maintenance treatment (including corticosteroids (less than or equal to 0.5mg/kg prednisone), TPO receptor agonists, etc.) must have a stable dose at least 4 weeks before the first administration, and azathioprine, danazol, cyclosporin A, tacrolimus, sirolimus, etc. must be stopped at least 4 weeks before the first administration; The end of rituximab treatment was>3 months；More than 6 months after splenectomy. Exclusion Criteria: Subjects with primary disease of important organs (liver, kidney, heart, etc.), or with immune system diseases; Secondary thrombocytopenia caused by various reasons, such as connective tissue disorders, bone marrow hematopoietic failure disease, myelodysplastic syndrome, malignancy, drugs, inherited thrombocytopenia, common variable immune deficiency, lymphoma, etc.; Subjects infected with human immunodeficiency virus (HIV); Uncontrollable or active infections during the screening period, including hepatitis B, hepatitis C, cytomegalovirus, EB virus, or positive syphilis antigen; Subjects with extensive and severe bleeding, such as hemoptysis, upper gastrointestinal hemorrhage, intracranial hemorrhage; Subjects with heart disease that requires treatment or hypertension that has been judged by researchers to be poorly controlled currently; Subjects with any venous or arterial thrombosis, atherosclerosis, and other diseases; Subjects with a history of malignant solid tumor or have received allogeneic stem cell transplantation or organ transplantation; Subjects with mental disorders who are unable to sign normal informed consent and conduct trials and follow-up; Subjects whose toxic symptoms caused by pre-trial treatment have not disappeared; Subjects with other serious diseases that may limit their participation in this trial (diabetes; severe cardiac insufficiency; myocardial obstruction or unstable arrhythmia or unstable angina pectoris in the last 6 months; gastric ulcer; active autoimmune disease, etc.); Subjects with septicemia or other irregular bleeding; Patients taking antiplatelet drugs at the same time; Any medical history or condition that the investigator deems unsuitable for participation in the study.