Quantification of BCR-ABL transcripts in peripheral blood cells and plasma of chronic myeloid leukemia patients at different stages of tyrosine kinase inhibitor treatment response

Purpose: To investigate the feasibility of using peripheral blood plasma samples as surrogates for blood cell sampling for quantification of breakpoint cluster region-Abelson oncogene (BCR-ABL) transcript levels to monitor treatment responses in chronic myeloid leukemia (CML) patients.
Methods: Peripheral blood samples were collected from 20 healthy individuals and 165 CML patients at various stages of treatment response. Level of BCR-ABL mutation gene transcripts were determined by RNA extraction and quantitative real time polymerase chain reaction (RT-PCR).
Results: The ratio of BCR-ABL transcripts/ABL transcripts in blood cells was significantly higher (p < 0.05) than in plasma for untreated and treated patients. Patients who received tyrosine kinase inhibitor (TKI) therapy and achieved major molecular response during treatment had the lowest mean ratio detected in blood cells (0.06 ± 0.0 %) and the ratio was below the detectable limit in plasma samples. Unlike plasma samples, BCR-ABL/ABL transcript ratios in blood cell samples strongly correlated with white cell counts in CML patients undergoing all types of treatment responses.
Conclusion: Blood cell sampling is more sensitive than plasma sampling in diagnosis and evaluation of CML treatment response.

Keywords
Chronic myeloid leukemia; Peripheral blood cells; Plasma RNA; Treatment response; Tyrosine kinase inhibitors