Thiotepa-Based Conditioning for Haploidentical HSCT in Older Patients With Severe Aplastic Anemia

This prospective, single-center, single-arm interventional study evaluates the safety and preliminary efficacy of a thiotepa-based conditioning regimen in patients aged 50 years or older with severe or very severe aplastic anemia undergoing haploidentical hematopoietic stem cell transplantation.

Inclusion Criteria: 1. Age 50 years or older. 2. Diagnosis of severe aplastic anemia or very severe aplastic anemia according to institutional diagnostic criteria. 3. Planned to undergo haploidentical hematopoietic stem cell transplantation with an eligible haploidentical donor. 4. Meets institutional performance status and cardiac, hepatic, renal, and pulmonary function requirements for transplantation. 5. Provides written informed consent. Exclusion Criteria: 1. Previous allogeneic hematopoietic stem cell transplantation. 2. Uncontrolled active infection at the time of enrollment or transplantation. 3. Known hypersensitivity to busulfan, fludarabine, thiotepa, basiliximab, or any relevant excipient. 4. Concurrent hematologic malignancy or another condition that, in the investigator's judgment, makes transplantation unsafe. 5. Pregnancy or breastfeeding. 6. Any serious uncontrolled medical, psychiatric, or social condition that could compromise protocol compliance or participant safety. \-