Comparison of molecular responses based on BCR-ABL1%IS results from an in-house TaqMan-based qPCR versus Xpert® assay in CML patients on tyrosine kinase inhibitor therapy

AbstractObjectives:Tyrosine kinase inhibitors (TKIs) have drastically changed the prospects for chronic myeloid leukemia (CML) patients. The European LeukemiaNet (ELN) recommends molecular monitoring of BCR-ABL1 mRNA levels at distinct time points to define an optimal response, warning, or failure of treatment.Methods:Sixty-four follow-up peripheral blood samples from CML patients on TKI were tested by two methods. Molecular responses based on BCR-ABL1%IS from an Xpert® BCR-ABL1 Monitor assay were compared with TaqMan-based qPCR.Results:Seven samples showed ‘molecularly undetectable leukaemia’ by both methods (11%). In-house qPCR showed 57 BCR-ABL1+ samples; 45/57 samples (79%) were concordant for ‘major molecular response’ (MMR, n = 32) and ‘no MMR’ (n = 13) by both assays, whereas nine were BCR-ABL1 negative by Xpert®. Identical molecular responses (i.e. ‘optimal’) were defined in 41 samples. Discordances seen in patients < 10 months on TKI (n = 2) had no impact on clinical management, whereas for patie...