Although the International Scale (IS) for reporting quantitative Philadelphia chromosome BCR–ABL1 fusion gene expression has helped standardize sequential testing for chronic myeloid leukemia (CML), a report from an external quality assessment team published in the British Journal of Haematology warns that there is still room for improvement.
Researchers from the United Kingdom’s NEQAS for Leucocyte Immunophenotyping program reviewed clinical trial data from 2007 to 2015 for BCR-ABL1 mRNA levels collected by reverse transcription quantitative polymerase chain reaction (RT-qPCR), which has proven important to the management of patients with CML. They then evaluated the effect of technical standardization and the IS on the accuracy of BCR-ABL1 testing.
“Comparison of participant results identified considerable variability at both high and low levels of disease, including therapeutically important decision points,” the authors reported. Results evaluated using the IS showed less variability, but different methods of converting to the IS produced consistently different median results within the data sets.
The results suggest that, though standardization has increased the comparability of results between centers, “there is still the need for further improvement in the processes of converting raw results to the IS in order to fully realize the benefits of molecular monitoring of CML.”
“Clearly, there is a risk of misclassifying the success or failure of any treatment at a particular time point,” the authors concluded. As a limitation of the study’s findings, the investigators noted that “in practice, most hematologists consider trends of residual disease over time in addition to levels of disease at fixed points.”
Source: Scott S, Travis D, Whitby L, et al. Measurement of BCR-ABL1 by RT-qPCR in chronic myeloid leukaemia: findings from an International EQA Programme. Br J Haematol. 2017 March 14. [Epub ahead of print]