Teriflunomide for Steroid-resistant/Relapse Immune Thrombocytopenia

Inclusion Criteria: 1. Diagnosis of primary immune thrombocytopenia (ITP) by excluding other supervened causes of thrombocytopenia 2. Patients with a platelet count \<30,000/μL or a platelet count \<50,000/μL with bleeding manifestations at the enrollment; 3. Patients who did not achieve a sustained response to treatment with full-dose corticosteroids for a minimum duration of 4 weeks or who relapsed during steroid tapering or after its discontinuation; 4. Willing and able to sign written informed consent. Exclusion Criteria: 1. Received chemotherapy or anticoagulants or other drugs affecting the platelet counts within 6 months before the screening visit; 2. Secondary immune thrombocytopenia (e.g. patients with HIV, HCV, Helicobacter pylori infection, malignancy, or patients with confirmed autoimmune disease); 3. Pregnancy or lactation; 4. Pre-existing acute or chronic liver disease, or serum alanine aminotransferase (ALT) greater than 2 times the upper limit of normal (ULN); 5. Current or recent (\< 4 weeks prior to screening) clinically serious viral, bacterial, fungal, or parasitic infection; 6. Have evidence of active tuberculosis (TB), or have previously had evidence of active TB and did not receive appropriate and documented treatment, or have had household contact with a person with active TB and did not receive appropriate and documented prophylaxis for TB; 7. Patients who are deemed unsuitable for the study by the investigator.