TPO-RA in Primary Immune Thrombocytopenia (ITP) in Patients Older Than 14 Years

Inclusion Criteria: * Men and women greater than or equal to 14 years of age. * Participants diagnosed with primary immune thrombocytopenia with two platelet counts of \< 30x10\^9/L or with bleeding at least 7 days apart，do not have evidence of other causes of thrombocytopenia (e.g.,pseudothrombocytopenia, myeloid fibrosis). * Previous treatment with poor response to first-line therapy and any of the maximum 4-week doses of eltrombopag, herombopag, avatrombopag, or 300U/kg/ day × 14-day rhTPO with no response to treatment (platelet count \< 30×109/L after treatment, or platelet count increase less than twice the baseline value, or with bleeding) * Participants willing and able to comply with the requirements of the study protocol, and sign the informed consent. Exclusion Criteria: * Patients diagnosed with secondary immune thrombocytopenia. * A history of arteriovenous thrombosis, disseminated intravascular coagulation, myocardial infarction, cerebral obstruction, thrombotic microangiopaemia, autoimmune diseases, malignant tumors, liver cirrhosis and other diseases that were not eligible for inclusion. * Liver disease with one of the following indicators: a. total bilirubin ≥ 2 times of the upper limit of normal; b. alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≥ 2 times the upper limit of normal value; Patients with renal disease (serum creatinine ≥ 1.5 times the upper limit of normal); * Subjects with known allergies to eltrombopag, herombopag, rh-TPO, avatrombopag, or any of excipients; * Have used rituximab in the past 3 months; * Splenectomy in recent 3 months; * Those who are not considered suitable for this study by the researcher; * Women who are pregnant or who intend to become pregnant in the near future are excluded.