PT  - JOURNAL ARTICLE
AU  - Latham, Susan
AU  - Bartley, Paul A
AU  - Budgen, Bradley
AU  - Ross, David M
AU  - Hughes, Elizabeth
AU  - Branford, Susan
AU  - White, Deborah
AU  - Hughes, Timothy P
AU  - Morley, Alexander A
TI  - <em>BCR-ABL1</em> expression, RT-qPCR and treatment decisions in chronic myeloid leukaemia
AID  - 10.1136/jclinpath-2015-203538
DP  - 2016 Sep 01
TA  - Journal of Clinical Pathology
PG  - 817--821
VI  - 69
IP  - 9
4099  - http://jcp.bmj.com/content/69/9/817.short
4100  - http://jcp.bmj.com/content/69/9/817.full
SO  - J Clin Pathol2016 Sep 01; 69
AB  - Aims RT-qPCR is used to quantify minimal residual disease (MRD) in chronic myeloid leukaemia (CML) in order to make decisions on treatment, but its results depend on the level of BCR-ABL1 expression as well as leukaemic cell number. The aims of the study were to quantify inter-individual differences in expression level, to determine the relationship between expression level and response to treatment, and to investigate the effect of expression level on interpretation of the RT-qPCR result.Methods BCR-ABL1 expression was studied in 248 samples from 65 patients with CML by determining the difference between MRD quantified by RT-qPCR and DNA-qPCR. The results were analysed statistically and by simple indicative modelling.Results Inter-individual levels of expression approximated a normal distribution with an SD of 0.36 log. Expression at diagnosis correlated with expression during treatment. Response to treatment, as measured by the number of leukaemic cells after 3, 6 or 12 months of treatment, was not related to the level of expression. Indicative modelling suggested that interpretation of RT-qPCR results in relation to treatment guidelines could be affected by variation in expression when MRD was around 10% at 3 months and by both expression variation and Poisson variation when MRD was around or below the limit of detection of RT-qPCR.Conclusions Variation between individuals in expression of BCR-ABL1 can materially affect interpretation of the RT-qPCR when this test is used to make decisions on treatment.