PRESENCE OR RE-APPEARANCE OF BCR-ABL-POSITIVE CELLS YEARS AFTER ALLOGENEIC BONE-MARROW TRANSPLANTATION FOR CHRONIC-PHASE CHRONIC MYELOGENOUS LEUKEMIA IN PATIENTS IN HEMATOLOGICAL REMISSION

Allogeneic bone marrow transplantation (BMT) is considered to be the o nly curative therapy for chronic myelogenous leukemia (CML). The cytog enetic marker of CML, the Philadelphia (Ph) chromosome, or the molecul ar alterations caused by the BCR-ABL gene fusion can be used to monito r the success of treatment. A sensitive two-step reverse-transcription polymerase chain reaction (RT-PCR) was done to score BCR-ABL-mRNA-pos itive leukemic cells in frozen bone marrow samples of 15 CML patients retrospectively. These patients, 4 females, 11 males, had undergone BM T during the first chronic phase after a preparative regimen consistin g of total body irradiation (TBI) and cyclophosphamide; median age at BMT was 38 years (range 20-49 years). At the time of this study, 8 pat ients were in cytogenetic and/or clincal remission. Seven patients rel apsed after BMT; all presented with Ph-chromosome-positive metaphases and BCR-ABL-positive cells at the time of relapse. In only 1 patient i n hematologic remission was no positive PCR analysis obtained in the t wo samples tested. However, 5 patients have remained or became Ph-chro mosome and/or PCR-positive after BMT without clinical symptoms of dise ase. In samples from another patient, transient presence of leukemic d ells was observed only early after BMT. Clinically, these patients wer e relapse free at days 3,055, 2,581, 2,252, 1,846, 1,839, 1,747, and 1 ,173 after BMT, respectively. Based on these data, the presence of sin gle BCR-ABL-positive cells >1 year after BMT has no prognostic signifi cance.