MINIMAL RESIDUAL DISEASE STATUS IN PRE-B ACUTE LYMPHOBLASTIC-LEUKEMIAPATIENTS AFTER CHEMOTHERAPY AND BONE-MARROW TRANSPLANTATION - ASSESSMENT OF THE ANTILEUKEMIC EFFECTS OF CHEMOTHERAPY AND BMT

We prospectively analyzed minimal residual disease (MRD) in four patie nts with B-cell precursor acute lymphoblastic leukemia who had been in complete remission for more than one year after chemotherapy and allo genic or autologous bone marrow transplantation (BMT). MRD was quantit atively estimated using polymerase chain reaction amplification to det ect the complementarity-determining region III of the immunoglobulin h eavy chain gene at limiting dilution DNA samples. Our study showed tha t remission induction chemotherapy reduced at most 2-logs of leukemia cells, and that subsequent consolidation chemotherapy induced further reduction of leukemia cells. In two cases, 10(-5) levels of MRD were d etected two months after BMT. However, no MRD was detected four months after BMT. We also showed the effectiveness of ex vivo purging with a nti-CALLA monoclonal antibodies which eliminated at least 2-logs of le ukemia cells in autologous BMT. Our results suggest that this detectio n system is useful for assessing the reduction of the original leukemi a clone, and that the presence of MRD within three months after BMT is not related to clinical outcome.