Allogeneic bone marrow transplantation for chronic granulocytic leukemia: progress and controversies

Over 1,000 patients with chronic granulocytic leukemia (CGL) have been given allogeneic bone marrow transplantation (BMT) in less than 10 years (Fefer, 1979, worldwide 1986), of which 455 by the IBMTR, 672 by the EBMT (with some overlap with the former) and 198 from Seattle, and some firm conclusions have been reached, while other aspects remain or have become controversial. It is now firmly established that younger patients in chronic phase (CP) do better than older ones, although the upper age limit is not defined. The hope that BMT could be successfully performed in the accelerated phase, thus allowing the postponement of a potentially hazardous procedure until it becomes unescapable, has been shown to be fallacious. Indeed, a significant difference in survival according to whether BMT was performed 'early' or 'late' in CP has been found in Seattle, but not confirmed by the IBMTR report. The treatment of the spleen (splenectomy, radiation, none) was found not to influence the outcome by the EBMT, but the same group is conducting a second, more extensive randomized study. Depletion of postthymic T lymphocytes is an efficient procedure to reduce graft-versus-host disease, and thus to facilitate non-HLA identical BMT, but the significant and distressing augmentation of relapses, both cytogenetic and clinical, reported by the majority of the clinical studies cast grave doubts on its utility, at least in its present form.