Use of a reduced-intensity conditioning regimen for allogeneic transplantation in patients with chronic myeloid leukemia.

Reduced-intensity conditioning that harnesses the potential of a graft-versus-tumor (GVT) effect has been proposed as an alternative to conventional myeloablative allogeneic stem cell transplantation. The primary aim is engraftment and this can be achieved with minimal immunosuppression. In this report, we describe the use of such regimens for CML in 17 patients who received human leukocyte antigen (HLA)-matched sibling allografts. Conditioning was with fludarabine, antithymocyte globulin (ATG) and busulfan for the first 11 patients, whereas fludarabine, busulfan and TBI were used for the remaining six patients. Engraftment was prompt in most of the cases. Complications and need for supportive therapy in the immediate post-transplant period were reduced drastically. Only two patients (both in the TBI group) died within the first 100 days. Acute graft-versus-host disease (GVHD) grade II-IV was seen in seven patients. Complications occurred later on. Chronic GVHD was observed in 11/17 patients. Lung infection and GVHD were the major killers. In surviving patients, after a median follow-up of 30 months (range 37-21 months), 6/17 (35.3%) are alive. Five are disease free and one patient is still in relapse even after a second donor lymphocyte infusion. Total treatment time and cost were more than with conventional transplants. We conclude that reduced-intensity transplantation still requires further refinement.