Bone marrow transplantation for patients with chronic myeloid leukaemia: T-cell depletion with Campath-1 reduces the incidence of graft-versus-host disease but may increase the risk of leukaemic relapse.

Between December 1983 and November 1985 we treated 39 patients with chronic myeloid leukaemia by chemoradiotherapy and transplantation from HLA-identical sibling donors using bone marrow that had been depleted of T cells ex vivo with the rat monoclonal antibody Campath-1. Twenty-eight of the patients were in the chronic phase (good-risk group) and 11 patients were in more advanced phases of the disease (accelerated phase or blastic transformation; poor-risk group). Of the patients of good risk 23 (82%) survive; the median duration of follow-up is 461 (range 111-776) days; of the 11 patients of poor risk four survive; the median duration of follow-up is 280 (range 189-658) days. Acute graft-versus-host disease (GVHD) of grade II or greater occurred in three (11%) of the patients of good risk and in six (55%) of the patients of poor risk. In the patients of good risk haematological evidence of relapse was seen in four and cytogenetic evidence of persisting or relapsed leukaemia (based on the finding of Philadelphia-chromosome-positive marrow metaphases more than 6 months after transplant) was seen in three other patients. In comparison with the patients of good risk transplanted with untreated marrow between February 1981 and December 1983, the incidence of acute GVHD was reduced significantly (P less than 0.001) but the risk of leukaemic relapse (including patients with only cytogenetic evidence of relapse) was increased (P less than 0.005). We conclude that T-cell depletion used in this manner may be associated with an increased risk of leukaemic relapse.