CORRESPONDENCE Purine Analog Regimens for Allogeneic Transplant?

To the Editor: For patients with leukemia undergoing allogeneic transplantation, the primary goals of the conditioning regimen include elimination of malignant cells for disease control and recipient lym-phoid cells to permit durable donor hematopoietic stem-cell engraft-ment. To meet these objectives, conditioning regimens for allogeneic transplantation are characteristically myeloablative and lymphoabla-tive. Such regimens are associated with substantial risk of morbidity and mortality. Older patients (age. 50 years) and those with confound-ing medical conditions are frequently not eligible for allogeneic transplantation because of the excess risks associated with these regimens. Attempts to improve the outcomes of allogeneic transplantation by altering the conditioning regimen have been explored. Clift et al1 observed that intensification of the conditioning regimen by increasing the total dose of irradiation significantly decreased the risk of leukemi