Cyclophosphamide Added to Standard Immunosuppressive Therapy With Herombopag as Front-line Therapy in Patients With Severe Aplastic Anemia

Inclusion Criteria: * Male or female age ≥ 12 years * Subject has a diagnosis of naïve severe or very severe aplastic anemia * ECOG performance status ≤2 * Unwilling or unable to receive allogeneic hematopoietic stem cell transplantation. * 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 either herombopag or cyclophosphamide. * Have an allergy to ALG * Uncontrolled systemic fungal, bacterial, or viral infection * Poorly controlled hypertension (≥140/90mmHg) or diabetes (a fasting plasma glucose concentration ≥7.0mmol/L or a random venous plasma glucose concentration ≥11.1mmol/L) * Abnormal liver or kidney function: ALT or AST \>3 ULN, or serum creatinine (sCr)≥ 2.5 ULN. * History of radiotherapy and chemotherapy for malignant solid tumors * 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.