This multi-center study aims to study the efficacy of TPO-RAs' transformation in Chinese ITP patients older than 14 years. This study will be conducted in ITP patients who had not responded to first-line in the previous treatment .

The primary objective of this study was to evaluate the efficacy of TPO-RAs' transformation in Chinese ITP patients older than 14 years who had not responded to first-line in the previous treatment.

100 eligible subjects will be enroll ed in this study.The dose will be adjusted according to the subject platelet count during the period from week 1 to week 6.

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.