Clinical value of quantitative long-term assessment of bcr-abl chimeric transcript in chronic myelogenous leukemia patients after allogeneic bone marrow transplantation.

BACKGROUND AND OBJECTIVE For purposes of therapeutic decision making, we used quantitative polymerase chain reaction (PCR) for molecular follow-up of 55 patients with chronic myeloid leukemia (CML) in complete remission (CR) after allogeneic bone marrow transplantation (BMT) from HLA compatible donors. DESIGN AND METHODS A total of 402 bone marrow samples from 40 patients transplanted in chronic phase (group 1) and 15 in accelerated/blastic phase (group 2) were analyzed by qualitative and quantitative PCR. RESULTS Regarding clinical outcome, 34/40 (85%) group 1 vs. 8/15 (54%) group 2 patients are alive. Only 1/40 (2.5%) group 1 patient relapsed, as against 6/15 (40%) in group 2 (p = 0. 0002). At qualitative PCR, 8/40 (19%) group 1 vs. 9/15 (60%) group 2 patients were positive, with a significantly greater total number of positive samples in group 2 (33/129, 27% vs. 16/273, 5%; p<0.001). The probability of qualitative PCR positivity >1 year after BMT was significantly lower in group 1 patients (4/40 pts, 10% vs. 9/15 pts, 60%; p = 0.01). At quantitative PCR, 4/8 (50%) group 1 patients were positive only once (< 400 transcripts/microg RNA). In group 2, 9/15 (60%) patients had 3 or more positive samples (always with >4,000 copies/mg RNA); therapeutic interventions (cyclosporin A discontinuation, temporary a-interferon or donor lymphocyte infusion) restored molecular remission in 4/9 (44%) cases. INTERPRETATION AND CONCLUSIONS This study indicates that quantitative PCR could provide practical indications capable of directing therapeutic interventions for transplanted CML patients, especially those transplanted in accelerated/blastic phase, for whom intensive monitoring is required.