Bone marrow transplants in chronic myelogenous leukemia: an overview of determinants of survival

The success of bone marrow transplantation in chronic myelogenous leukemia (CML) is strongly associated with the phase of the disease at the time of transplantation. For allogeneic transplants from siblings with identical human leukocyte antigens, the 3-year survival rate for recipients in chronic phase ranges from 55% to 70%, whereas survival falls to approximately 30% for recipients in accelerated phase and to 0% to 20% for patients receiving transplants during blast crisis. Detailed analysis of data pooled from 405 patients demonstrated that the 3-year probability of relapse was 48% for recipients of T-cell-depleted bone marrow, but only 9% for recipients of non-T-cell-depleted bone marrow (relative risk, 5.4; P less than .0001). Regardless of transplant T-cell status, however, patients who developed chronic graft-versus-host disease (GVHD) were less likely to relapse at 4 years when compared with recipients without chronic GVHD (6% v 24%; relative risk, 3.1; P less than .01). Survival was correlated with severity of acute GVHD and age. Allogeneic bone marrow transplantation from unrelated donors can be useful in expanding the patient population eligible for transplantation. A study of recipients of transplants from unrelated donors showed a 3-year projected survival of 55% for chronic phase patients, and 22% for patients with advanced disease. However, a high rate of graft failure (10%) and grade II to IV acute GVHD can be expected. Preliminary data suggest that ex vivo treatment of autologous bone marrow with interferon can effect complete or partial Philadelphia (Ph) chromosome negative bone marrow mosaicism, although appearance of Ph chromosome negative metaphases may not be persistent. Thus, interferon treatment of autologous bone marrow may play a more significant role in the treatment of CML.