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

Design : Prospective, single-center, single-arm, open-label Phase IIB trial. Intervention : P-ATG : 15 mg/kg/day IV ×5 days. Cyclosporine : 3 mg/kg/day (adjusted to trough 100-200 μg/L). Hetrombopag : 15 mg daily. Follow-Up : Weekly for 24 weeks, with bone marrow evaluation at 24 weeks. Inclusion Criteria : Confirmed diagnosis of VSAA/SAA. Age ≥65 years. Completion of all screening assessments. Ability to swallow oral medication. 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.