Leukemic cell kill in autologous bone marrow transplantation: in vivo or in vitro?

Both the contribution of high dose chemo-radiotherapy ("conditioning treatment") prior to autologous bone marrow transplantation (ABMT) and "purging" of autologous marrow grafts to the prevention of leukemia relapse are being addressed in the present communication. Based on both preclinical and clinical studies, it is concluded that cures achieved after ABMT are mainly due to effective eradication of residual leukemic cells in the host. The chance that leukemia will relapse is due to leukemic cells reinfused with the graft is estimated to be less than 10%.