Cartridge-based automated BCR-ABL1 mRNA quantification: solving the issues of standardization, at what cost?

Abstract

BackgroundMolecular monitoring of chronic myeloid leukemia patients treated with tyrosine kinase inhibitors is essential for therapeutic stratification. Inter-laboratory reproducibility is, therefore, a crucial issue which requires standardization and strict alignment of BCR-ABL1 values to the international scale. An automated cartridge-based assay (Xpert BCR-ABL Monitor TM , Cepheid) had been proposed as a robust alternative to non-automated assays. This study aimed to compare inter-laboratory reproducibility of automated and non-automated quantification, the possibility of converting automated results to the international scale, and the potential economic impact of automation. Design and MethodsOne hundred and eighteen blood samples from chronic myeloid leukemia patients treated with tyrosine kinase inhibitors were prospectively analyzed in two laboratories using both automated and non-automated assays. The economic evaluation involved a micro-costing study and average costs were assessed as a function of sample throughput. ResultsAutomated assays achieved similar inter-laboratory reproducibility to highly standardized nonautomated assays and a short delay (≤6 h) between sampling and blood lysis had a positive impact on inter-laboratory reproducibility. Reporting automated BCR-ABL1 ratios on the international scale was possible using a specific conversion factor which may vary with batches. Cost assessment showed that automated assays could be relevant for annual activity levels below 300 since average costs were lower than those of the non-automated assays. ConclusionsThe Xpert BCR-ABL Monitor TM assay could be appropriately used in a near-patient setting for routine quantification of e13/e14-a2 transcripts, preferably in partnership with a regional reference laboratory. However, its prognostic impact relative to non-automated quantification remains to be tested prospectively within appropriate clinical trials.

Molecular monitoring of chronic myeloid leukemia: principles and interlaboratory standardization

“…These secondary reference reagents may be manufactured and calibrated by companies, reference laboratories, or other agencies and made available to testing laboratories either on a commercial basis or as part of specific national or regional standardization initiatives. At the time of writing, a number of different kits, systems, and secondary reagents are available that enable testing laboratories to derive patient results on the IS [28,29]. Comparative data is, however, very limited at present, and it is not possible to say which of these approaches is best, but in principle, the use of calibrated reagents is likely to replace the use of CFs in the coming years [30].…”

“…Initially, the only mechanism for laboratories to adopt the IS was to establish a laboratory-specific conversion factor (CF) using a process initiated by the Adelaide laboratory (33). For a testing laboratory to establish a CF, a series of samples (typically [20][21][22][23][24][25][26][27][28][29][30] are exchanged with a reference laboratory that span at least three logs of detectable disease but do not exceed an IS value of roughly 10 %. Samples are analyzed by both centers over a period of 2-3 months typically in order to take into account common intralaboratory variables, e.g., different operators and different batches of reagents.…”

Present and future of molecular monitoring in chronic myeloid leukaemia

“…The cartridge includes reagents to detect BCR-ABL1 b2a2 and b3a2 fusion transcripts as well as the ABL1 as an endogenous control. High linear correlation with conventional RQ-PCR results has been confirmed by several studies (Winn-Deen et al, 2007;Cayuela et al, 2011;Lopez-Jorge et al, 2012;Bochicchio et al, 2014). Sensitivity, initially deemed to be a potential issue (because of the low sample volumes analysed), has recently been shown to be comparable to that of conventional RQ-PCR down to MR 4.5 response levels (Bochicchio Boeckx et al, 2015).…”

Comment on: Technical Issues Behind Molecular Monitoring in Chronic Myeloid Leukemia

“…However, automating several or all aspects of the process would substantially reduce the impact of these pre-analytical variables. An example of such an available platform is the cartridge-based Xpert Ò BCR-ABL1 Monitor system, which is validated in several studies and is able to provide a feasible solution to many of the standardisation issues surrounding BCR-ABL1 monitoring [5][6][7].…”