Molecular monitoring in chronic myeloid leukemia (CML)

The pathognomonic genetic alteration in CML is the formation of the BCR-ABL fusion gene, which produces a constitutively active tyrosine kinase that drives leukemic transformation. Targeted tyrosine kinase inhibitor treatment is the cornerstone of modern therapy for this hematologic malignancy. Analysis of BCR-ABL [through reverse transcriptase-quantitative polymerase chain reaction (RT-QPCR)] is the gold standard approach for quantitatively assessing minimal residual disease and monitoring the efficacy of tyrosine kinase inhibitor therapy in CML patients. The continuous therapeutic improvement has led to increasingly ambitious treatment endpoints, which, in turn, require more and more refined measurement and definition of molecular response levels. For these reasons standardization efforts of monitoring by RT-QPCR are now focused on ensuring reliable and harmonized expression of quantitative results.