Efficacy and Safety of Sirolimus With or Without Cyclosporin A in Chinese Patients With Aplastic Anemia Refractory/Intolerant to Cyclosporin A

Inclusion Criteria: 1. Age ≥ 18 years; 2. Diagnosed with acquired aplastic anemia (AA), excluding congenital AA; 3. At least one of the following criteria met at enrollment: hemoglobin \< 100 g/L, platelets \< 50 × 10⁹/L, or neutrophils \< 1.0 × 10⁹/L; 4. At enrollment, meeting at least one of the following conditions: ① Cyclosporine A (CsA) ineffective: (CsA) used for at least 3 months without achieving partial response (PR), or disease relapse occurred; ② CsA intolerant: Unsuitable for standard dose CsA treatment due to adverse events or underlying conditions. 5. No active infections; 6. Not pregnant or breastfeeding; 7. Willing to sign the consent form; 8. Eastern Cooperative Oncology Group (ECOG) performance status score of 0-2. Exclusion Criteria: 1. Pancytopenia caused by other reasons, such as myelodysplastic syndrome (MDS); 2. Evidence of clonal hematopoietic system bone marrow diseases (e.g., MDS or acute myeloid leukemia, AML); 3. Paroxysmal nocturnal hemoglobinuria (PNH) clone ≥ 50%; 4. History of hematopoietic stem cell transplantation (HSCT) before enrollment; 5. Previous use of sirolimus or allergy to sirolimus; 6. Severe adverse events to CsA in the past, making it unsuitable for reuse; 7. Uncontrolled infection or bleeding with standard treatment; 8. Active infections with HIV, HCV, or HBV, liver cirrhosis, portal hypertension; 9. Any concurrent malignancy within the past 5 years, except for localized basal cell carcinoma of the skin; 10. History of thromboembolic events, myocardial infarction, or stroke (including antiphospholipid antibody syndrome), or current use of anticoagulants; 11. Pregnant or breastfeeding women; 12. Participation in other clinical trials within the past 3 months.