A Study to Evaluate the Safety and Efficacy of Hetrombopag Olamine in Severe Aplastic Anemia （SAA） Patient

Inclusion Criteria: 1. Previous diagnosis of refractory severe aplastic anemia, not meeting partial response criteria after at least one treatment course of immunosuppressive therapy, not suitable or unwilling to do hematopoietic stem cell transplantation. 2. Platelet count ≤ 30×109/L. 3. Signed informed consent. Exclusion Criteria: 1. Bleeding and/or Infection not adequately responding to appropriate therapy. 2. Patients with a PNH clone size in neutrophils of ≥50%. 3. Treatment with immunosuppressive therapy within 6 months prior to study entry. 4. Any laboratory or clinical evidence for HIV infection. Any clinical history for hepatitis C infection; chronic hepatitis B infection; or any evidence for active hepatitis at the time of subjects screening. 5. ALT\> 2.5 x upper limit of normal (ULN), AST\> 2.5 x upper limit of normal (ULN) DBLI\> 1.5 x upper limit of normal (ULN), Scr\> upper limit of normal (ULN). 6. Subjects diagnosed with cirrhosis or portal hypertension. 7. Subjects diagnosed with tumor. 8. Patients with any prior history of congestive heart failure, arrhythmia, and peripheral arteriovenous thrombosis within 1 year. With a history of myocardial infarction or cerebral infarction within 3 months. 9. ECOG Performance Status of 3 or greater. 10. Female subjects who are nursing or pregnant within 6 months. 11. Subjects cannot take effective contraception. 12. Subjects have participated in other clinical trial within the 3 months prior to study entry.