The Safety, Tolerability, Pharmacokinetics and Preliminary Efficacy of HMPL-523 in Immune Thrombocytopenia Patients

Inclusion Criteria: 1. Signed informed consent form 2. 18\~75 years old male of female 3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 4. Diagnosed immune thrombocytopenia before randomization with platelet decrease for more than 6 months. 5. Patients with refractory or relapsed ITP who have been treated with 1st line anti-ITP regimen or have experienced splenectomy. 6. Relative stable disease with World Health Organization (WHO) bleeding score of 0-1 and no rescue treatment needed within 2 weeks based on investigator's judgment. 7. Laboratory tests meet the following conditions： * During screening stage, twice PLT\<30x10\^9/L(exceed 24 hours) * Hb≥90g/L(if iron-deficiency anemia,Hb\>80g/L),WBC\>2.5x10\^9/L, NEU\>1.8x10\^9/L * Crea≤1.5xULN and CCR≥50mL/min * TBIL、ALT、AST≤1.5xULN * Amylase、lipase\<ULN * INR、APTT\<20%xULN Exclusion Criteria: 1. Patients with secondary thrombocytopenia or patients have other auto immune diseases who need long term steroids or immunosuppressants treatment. 2. Patients with Myelofibrosis, Myelodysplastic syndrome, Aplastic anemia, or other hematologic malignancies. 3. Have splenectomy within 12 weeks before randomization 4. Major surgery was performed within 4 weeks before randomization;Or require major elective surgery during the study period. 5. Have malignant tumor(except basal cell carcinoma of skin and carcinoma in situ of cervix) 6. Have previous/significant arterial/venous embolic disease 7. History of serious cardiovascular disease, or QTc≥450 ms. 8. Patients with resistant hypertension (Systolic blood pressure ≥140 mmHg or Diastolic blood pressure ≥90 mmHg) 9. Has a history of severe gastrointestinal diseases, such as dysphagia, active gastric ulcer, and is unable to take oral medication or has absorption disorder 10. HIV infection 11. Uncontrolled, active infections 12. Known history of clinically significant liver disease, such as hepatitis b（HBV DNA ≥2000IU/mL (or ≥1×104 copies)）, hepatitis c, or cirrhosis 13. Prior anti-ITP emergency treatment within 2 weeks before randomization. 14. Prior anti-ITP treatment within 4 weeks before randomization except for stable dose steroids, including but not limited to Thrombopoietin, thrombopoietin receptor agonist, azathioprine, cyclosporine A and mycophenolate mofetil. 15. Any condition requiring anti-coagulant therapy or the regular use of any medication having effluence to Platelet function. 16. Exposure to Rituximab 14 weeks prior to randomization. 17. Treament with Chinese medicine within 1 week before randomization. 18. Use of strong cytochrome P450 isoform 3A inhibitors and inducers and drugs metabolized by cytochrome P450 isoform 3A, cytochrome P450 isoform 2B6, and cytochrome P450 isoform 1A2, and are identified as narrow therapeutic drugs within 14 days or 5 half-lives, whichever is longer, prior to initiation of study treatment. 19. Prior treatment with any spleen tyrosine kinase (SYK) inhibitors (eg, fostamatinib) 20. Allergic to study drug active ingredient or excipient 21. Subjects who have participated in clinical studies of drugs or invasive medical devices within 4 week before randomization 22. Subjects have severe psychological or mental abnormalities 23. Alcoholic or drug abuser 24. Female subjects during pregnancy and lactation 25. The investigator considered that the subjects were not suitable to participate in the study