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.