Inclusion Criteria:  Participant must be at least 18 years of age at the time of the screening. Participant may be male or female. Participant has a confirmed diagnosis of ITP according to the 2019 International Working Group assessment at screening. Participant who didn't respond to eltrombopag retreatment (75mg by mouth once a day for 14 days) after eltrombopag previous treatment inefficient or relapsed (platelet count below 30 × 10^9/L or below 2-fold increase from baseline platelet count, or bleeding). Bone marrow biopsy is performed in participants over 60 years to exclude hematological malignancies.  Exclusion Criteria:  Participant has evidence of a secondary cause of immune thrombocytopenia (e.g. leukemia, lymphoma, common variable immune-deficiency, systemic lupus erythematosus, autoimmune thyroid disease, past medical history of untreated H. pylori infection) or to drug treatments (e.g. heparin, quinine, antimicrobials, anticonvulsants) or participant has a multiple immune cytopenia, e.g. Evan's syndrome. Participant has clinically life-threatening bleeding (e.g. central nervous system bleeding, menorrhagia with significant drop in hemoglobin). Participant has a history of coagulopathy disorders other than ITP. Participant has a history of arterial or venous thromboembolism (e.g. stroke, transient ischemic attach, myocardial infarction, deep vein thrombosis or pulmonary embolism) within the 6 months prior to randomization or requires anticoagulant treatment. Participant has 12-lead ECG with changes considered to be clinically significant upon medical review at baseline. Participant has severe renal impairment (glomerular filtration rate less than 45ml/min/1.73 m2). Participant has 3 × upper limit of normal of any of the following: alanine aminotransferase, aspartate aminotransferase, or alkaline phosphatase. Participant has received corticosteroids, rh-TPO, romiplostim, or immunosuppression within 4 weeks before screening. Participant with any of the following conditions: severe immunodeficiency, active or previous malignancy, human immunodeficiency virus (HIV), hepatitis B or C virus infection, pregnancy or lactation.