[Evolution of BCR-ABL1 Testing for Chronic Myeloid Leukemia Under Tyrosine Kinase Inhibitor Treatment]

The advent and long-term use of tyrosine kinase inhibitors in molecular target therapy for chronic myeloid leukemia have resulted in a marked improvement of treatment outcomes. This has changed'the algorithm of the laboratory process for the diagnosis and therapeutic monitoring of chronic myeloid leukemia. It includes defining the molecular typing of BCR-ABL1 to establish the diagnosis, and a quantitative and/or high- sensitivity assay for minimal residual disease to evaluate the treatment response. Along with improved long-term survival outcomes, new issues have arisen regarding the best index to use for the improved clinical outcomes, such as treatment-free remission. To this end, clinical and laboratory monitoring of CML patients has been investigated. Novel methodologies and technologies have been applied to improve decision-making on patient care, tailoring the treatment to the individual characteristics of each patient, including an early index for the treatment response and deeper molecular response to realize treatment-free survival, and BCR-ABLI kinase domain mutation screening for refractory disease. In response to the advancement and applications of these emerging technologies, proper laboratory practice with the quality assurance of testing is expected. [Review].