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

The 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.The 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.Results Our 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.Conclusions In 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.Fil: Ruiz, María Sol. Fundación Cáncer. Centro de Investigaciones Oncológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sánchez, María Belén. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Vera Contreras, Yuly Masiel. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Agrielo, Evangelina. Laboratorio Especialidades Bioquímicas; ArgentinaFil: Alonso, Marta. Hospital Nacional Profesor Alejandro Posadas; ArgentinaFil: Altuna, María Eugenia. Clinica Roberto Raña; ArgentinaFil: Anchordoqui, María Sol. Argenomics; ArgentinaFil: Asinari, Mariana. Hospital Privado Centro Médico de Córdoba; ArgentinaFil: Bonetto, María Elisa. Hospital Rawson San Juan; ArgentinaFil: Camargo, Mauricio. Laboratorio Medellin; ColombiaFil: Giere, Isabel. Fundación Para Combatir la Leucemia; ArgentinaFil: González, Javier. Meyer Lab; ParaguayFil: Granda Alacote, Ana Cecilia. Laboratorios Medicos Lima; PerúFil: Guerra, Javier. Nanopharmacia Diagnóstica Mexico; MéxicoFil: Gutiérrez, Marina. Stamboulian; ArgentinaFil: Maldonado, Cecilia. Manlab; ArgentinaFil: Makiya, Ricard. No especifíca;Fil: Manrique, Gonzalo. Asociacion Española de Montevideo; UruguayFil: Monaco, María Eugenia. Laboratorio Tucuman; ArgentinaFil: Rozo, Juan Carlos. Unidad de Diagnóstico Hemato Oncológico; ColombiaFil: Santamaría Martín, Carlos Jose. Hospital de Niños San Jose de Costa Rica; Costa Rica. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Seravalle, Analía. Civic Rosario; ArgentinaFil: Zea, Olga. Laboratorio Medellin Colombia; ColombiaFil: Zubillaga, María Noel. Asociación Española de Socorros Mutuos; UruguayFil: Mordoh, José. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Larripa, Irene Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bianchini, Michele. Fundación Cáncer. Centro de Investigaciones Oncológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

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

IntroductionTreatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase is considered a safe option if suitable molecular monitoring is available. However, the question arises as to which factors can contribute to the maintenance of TFR, and immunologic surveillance of the remaining leukemic cells is believed to be one of them. Argentina Stop Trial is an open-label, single-arm, multicenter trial assessing TFR after tyrosine kinase inhibitors interruption, that after more than 4 years showed a successful TFR rate of 63%.MethodsIn this context, we set up an immunological study by flow cytometry in order to analyze specific NK cell subsets from peripheral blood patient samples both at the time of discontinuation as well as during the subsequent months.ResultsAt the time of discontinuation, patients show a mature NK cell phenotype, probably associated to TKI treatment. However, 3 months after discontinuation, significant changes in several NK cell receptors occurred. Patients with a higher proportion of CD56dim NK and PD-1+ NK cells showed better chances of survival. More interestingly, non-relapsing patients also presented a subpopulation of NK cells with features associated with the expansion after cytomegalovirus infection (expression of CD57+NKG2C+), and higher proportion of NKp30 and NKp46 natural cytotoxicity receptors, which resulted in greater degranulation and associated with better survival (p<0.0001).DiscussionThis NK cell subset could have a protective role in patients who do not relapse, thus further characterization could be useful for patients in sustained deep molecular response

Elevated plasma levels of IL-6 and MCP-1 selectively identify CML patients who better sustain molecular remission after TKI withdrawal

Abstract Treatment-free remission (TFR) in chronic myeloid leukemia (CML) is safe under adequate molecular monitoring, but questions remain regarding which factors may be considered predictive for TFR. Argentina Stop Trial (AST) is a multicenter TFR trial showing that 65% of patients sustain molecular remission, and the prior time in deep molecular response (DMR) was associated with successful TFR. Luminex technology was used to characterize cytokines in plasma samples. Using machine learning algorithms, MCP-1 and IL-6 were identified as novel biomarkers and MCP-1low/IL-6low patients showed eightfold higher risk of relapse. These findings support the feasibility of TFR for patients in DMR and MCP-1/IL-6 plasma levels are strong predictive biomarkers

DataSheet_1_In-depth characterization of NK cell markers from CML patients who discontinued tyrosine kinase inhibitor therapy.docx

IntroductionTreatment-free remission (TFR) in patients with chronic myeloid leukemia in chronic phase is considered a safe option if suitable molecular monitoring is available. However, the question arises as to which factors can contribute to the maintenance of TFR, and immunologic surveillance of the remaining leukemic cells is believed to be one of them. Argentina Stop Trial is an open-label, single-arm, multicenter trial assessing TFR after tyrosine kinase inhibitors interruption, that after more than 4 years showed a successful TFR rate of 63%.MethodsIn this context, we set up an immunological study by flow cytometry in order to analyze specific NK cell subsets from peripheral blood patient samples both at the time of discontinuation as well as during the subsequent months.ResultsAt the time of discontinuation, patients show a mature NK cell phenotype, probably associated to TKI treatment. However, 3 months after discontinuation, significant changes in several NK cell receptors occurred. Patients with a higher proportion of CD56dim NK and PD-1+ NK cells showed better chances of survival. More interestingly, non-relapsing patients also presented a subpopulation of NK cells with features associated with the expansion after cytomegalovirus infection (expression of CD57+NKG2C+), and higher proportion of NKp30 and NKp46 natural cytotoxicity receptors, which resulted in greater degranulation and associated with better survival (pDiscussionThis NK cell subset could have a protective role in patients who do not relapse, thus further characterization could be useful for patients in sustained deep molecular response.</p