Background. Molecular biology methods based on reverse transcription and polymerase chain reaction (RT-PCR) are
able to detect the presence of BCR-ABL transcripts in chronic myeloid leukemia (CML). In this study we present our
experience with monitoring of residual disease using real-time PCR with hybridization probes detection in patients
treated with imatinib mesylate and in collected peripheral blood progenitor cells (PBPC).
Methods and Results.We measured the level of BCR-ABL transcripts in peripheral blood cells of 27 subjects before
and in the course of the imatinib treatment. The median of relative quantity of BCR-ABL in the blood before imatinib
therapy was 2.55%. The number of the transcripts in 23 imatinib-sensitive subjects decreased to 0.02% in 6
months. After 12 months of the treatment the BCR-ABL median was 0.005%. Subsequent levels fluctuated between
values below the detection limit (DL, 0.001%) and 0.005%. Three patients were primarily resistant to imatinib with
the BCR-ABL range of 0.13%-11,7% during the treatment. One subject showed marks of molecular relapse after 18
months of the treatment. Only two of 16 filgrastim-stimulated patients had BCR-ABL levels in the blood and in collected
PBPC below DL. In other subjects BCR-ABL transcripts were determined within the measurable range
Conclusions. Taking into account prognostic importance, the measurement of BCR-ABL transcripts is an effective
approach to monitoring of residual CML kinetics. Evaluation of BCR-ABL levels in collected PBPC can complete
information on quality of the cells in potential autotransplants, and choose subsequent therapeutic protocols and
BCR-ABL, RT-PCR, imatinib, minimal residual disease, leukemia.