- Myeloablative preparative regimen: Patients undergo total body irradiation twice daily on days -10 and -9 and receive thiotepa intravenously (IV) over 4 hours on days -8 and -7, fludarabine phosphate IV over 30-60 minutes on days -7 to -3, and antithymocyte globulin IV over 4-6 hours on days -5 to -2.