Programme for Harmonization to the International Scale in Latin America for BCR-ABL1 quantification in CML patients: findings and recommendations

Abstract

ObjectivesThe quantitation of BCR-ABL1 mRNA is mandatory for chronic myeloid leukemia (CML) patients, and RT-qPCR is the most extensively used method in testing laboratories worldwide. Nevertheless, substantial variation in RT-qPCR results makes inter-laboratory comparability hard. To facilitate inter-laboratory comparative assessment, an international scale (IS) for BCR-ABL1 was proposed.MethodsThe laboratory-specific conversion factor (CF) to the IS can be derived from the World Health Organization (WHO) genetic reference panel; however, this material is limited to the manufacturers to produce and calibrate secondary reference reagents. Therefore, we developed secondary reference calibrators, as lyophilized cellular material, aligned to the IS. Our purpose was both to re-evaluate the CF in 18 previously harmonized laboratories and to propagate the IS to new laboratories.ResultsOur field trial including 30 laboratories across Latin America showed that, after correction of raw BCR-ABL1/ABL1 ratios using CF, the relative mean bias was significantly reduced. We also performed a follow-up of participating laboratories by annually revalidating the process; our results support the need for continuous revalidation of CFs. All participating laboratories also received a calibrator to determine the limit of quantification (LOQ); 90% of them could reproducibly detect BCR-ABL1, indicating that these laboratories can report a consistent deep molecular response. In addition, aiming to investigate the variability of BCR-ABL1 measurements across different RNA inputs, we calculated PCR efficiency for each individual assay by using different amounts of RNA.ConclusionsIn conclusion, for the first time in Latin America, we have successfully organized a harmonization platform for BCR-ABL1 measurement that could be of immediate clinical benefit for monitoring the molecular response of patients in low-resource regions.

Molecular BCR::ABL1 Quantification and ABL1 Mutation Detection as Essential Tools for the Clinical Management of Chronic Myeloid Leukemia Patients: Results from a Brazilian Single-Center Study

“…This led to the establishment of an international scale (IS) for BCR::ABL1 quantification, which resulted in a laboratory-specific conversion factor (CF). For Brazilian and Latin American laboratories, a secondary reference calibrators panel was developed by Bianchini et al to provide a harmonization panel for BCR::ABL1 measurement that could be applied to the molecular monitoring response of patients [ 40 ].…”

In-depth characterization of NK cell markers from CML patients who discontinued tyrosine kinase inhibitor therapy

“…PB samples were collected once a month for the first 6 months after discontinuation of TKI, then every 2 months until month 12, and every 3 months thereafter for at least 2 years. Molecular response was assessed with RT-qPCR at 2 designated standardized laboratories (“Programme for harmonization to international scale”) ( 22 , 23 ), and reported as the ratio of BCR-ABL1 to ABL1 on the International Scale. Molecular recurrence was defined as loss of major molecular response (MMR), corresponding to expression of more than 0.1% BCR-ABL1 IS transcripts at any time.…”

Treatment-free remission in patients with chronic myeloid leukemia: recommendations of the LALNET expert panel

“…To have an immediate clinical benefit on molecular response monitoring for patients in low-resource regions, this platform identified existing flaws in BCR-ABL quantification and brought up several technical recommendations to improve comparability between laboratories. 21 The strict and more frequent monitoring, as recommended to make TFR feasible, has not yet been recognized by all government health authorities and insurance companies in LA countries. Various LA countries have local cooperative working groups with special interest in CML management but no regional collaborative approach in TFR local recommendations has been developed until now.…”

“…To have an immediate clinical benefit on molecular response monitoring for patients in low-resource regions, this platform identified existing flaws in BCR-ABL quantification and brought up several technical recommendations to improve comparability between laboratories. 21 …”