Reduced Dose of Cyclophosphamide Combined With Standard Immunosuppressive Therapy to Treat Severe Aplastic Anemia

Inclusion Criteria: * Subject has a diagnosis of naïve severe or very severe aplastic anemia * Male or female age ≥ 12 years * Unwilling or unable to receive allogeneic hematopoietic stem cell transplantation. * ECOG performance status ≤2 * Willing and able to comply with the requirements for this study and written informed consent. Exclusion Criteria: * Previously received immunosuppressive therapy \> 4 weeks * Previously treated with TPO-RA \> 4 weeks * Have an allergy or intolerance to anti-lymphocyte globulin, cyclosporine, herombopag or cyclophosphamide. * Uncontrolled fungal, bacterial, or viral infection. Hepatitis-associated aplastic anemia is allowed; hepatitis B or C infection is permitted unless it causes severe liver failure. * Tested positive for HIV or syphilis * Presence of severe liver, kidney, or heart failure, or other life-threatening comorbidities. * History of radiotherapy and chemotherapy for malignant solid tumors in recent 5 years * Combined with other serious disorders * Pregnant or breast-feeding patients * Patients considered to be ineligible for the study by the investigator for reasons other than the above.