Dose-attenuated IST and Hetrombopag in Elderly (≥65 Years) Patients With Severe Aplastic Anemia

Inclusion Criteria: * Clinical diagnosis of VSAA/SAA. * Age ≥65 years. * Completion of all screening assessments. * Must be able to swallow tablets. * Signed informed consent (by patient or legal guardian if patient is incapacitated). Exclusion Criteria: * Clonal cytogenetic abnormalities (excluding isolated -Y or +8). * Prior treatment with ATG/high-dose cyclophosphamide. * Prior cyclosporine/tacrolimus use \>12 months. * Prior TPO-RA therapy \>3 months. * Uncontrolled malignancies or conditions contraindicating ATG. * Severe organ dysfunction (e.g., creatinine ≥177 μmol/L). * Investigator judgment of unsuitability.