Compared Molecular Monitoring of BCR-ABL Transcripts in Peripheral Blood and Bone Marrow Samples in CML Patients after Allogeneic Hematopoiteic Stem Cell Transplant.

Background. Molecular monitoring of the BCR-ABL transcripts in patients with chronic myeloid leukemia (CML) using quantitative real-time polymerase chain reaction (QRT-PCR) provides important information about the leukemia cell mass and the response to therapy. After allogeneic hematopoietic stem cell transplants (HSCT) patients with persistently positive levels of BCR-ABL transcript have a molecular relapse and some of these patients progress to develop a cytogenetic or hematologic relapse.

Objectives. To test whether molecular detection of BCR-ABL transcripts is comparable using peripheral blood (PB) and bone marrow (BM) aspirate samples after allogeneic HSCT.

Patients and Methods. BCR-ABL transcripts were monitored the interval of time 2003 – 2005 in 118 patients who received an allogeneic HSCT in chronic or advanced disease phase. BCR-ABL transcripts were evaluated concomitantly in 200 blood samples and 200 marrow samples (total 400 determinations) using real time PCR (QRT-PCR) assay to analyze BCR-ABL gene rearrangement (p210 b2a2 and b3a2). A complete molecular response (CMR) both for PB and BM we defined has undetectable levels of p210 and Major molecular response (MMR) was defined when p210/ABL ratios where <0.02%.

Results. 135 double BM+PB determinations (67%) proved BCR-ABL negative; 61 double determinations (31%) were classified as “persistently positive” both in peripheral blood and in blood marrow; 4 determinations (2%) were discordant. Therefore 196/200 BCR-ABL determinations in peripheral blood and bone marrow (98 %) were concordant.

Conclusions. This study shows that BCR-ABL QRT PCR monitoring of CML patients after allogeneic HSCT with peripheral blood cells is concordant with bone marrow cells in 98% of cases, and thus may be used to monitor the disease. This may be relevant for patients, especially when quality of life issues are discussed together with the need for post-transplant monitoring.