Technical challenges for standardization of molecular monitoring in chronic myeloid leukaemia in developing countries

Quantification of BCR-ABL after treatment with tyrosine kinase inhibitors is an important therapeutic indicator for patients with chronic myeloid leukaemia (CML). An international scale (IS) for BCR-ABL was established in 2012 to improve the comparability of results between different laboratories. BCR-ABL measurement is technically challenging, especially in developing countries where the process of standardization isn’t easily available. The aim of this study was to assess the technical advantages of reporting results on the IS using the GeneXpert BCR-ABL assay, compared to the RQ-PCR standard method currently recommended by the European Leukaemia Network but not standardised in our laboratory and to compare the results obtained by both methods. BCR-ABL transcript quantification was performed in 51 samples from CML patients by both methods. The operator hands-on time was reduced using the automated method. A good linear correlation was observed in the results between the two methods. The concordance at logarithmic intervals reached 64%. When the major molecular response (MMR) and the early molecular response (EMR) were analysed, 90% and 80% agreement, respectively, were achieved. However, the discordances in the remaining cases could have misled the therapeutic approach if only a standard method was used. The complexity of the process to establish a laboratory-specific conversion factor in developing countries can be overcome by the use of the GeneXpert automated system, which represents a rapid, accurate and reliable clinical tool to correctly define molecular responses on the IS and to allow clinicians to achieve better patient management.