Human ABL1 peptide

PurposeThe advent of tyrosine kinase inhibitor (TKI) therapies has revolutionized the treatment of chronic myeloid leukemia (CML). The European LeukemiaNet (ELN) recommends quantification of BCR-ABL1 transcripts by real-time quantitative PCR every 3months during TKI treatment. Since a proportion of patients in deep molecular response (DMR: MR4, MR4.5, MR5) maintain remission after treatment stop, assessment of DMR is crucial. However, systematically collected molecular data, monitored with sensitive standardized assays, are not available outside clinical trials.MethodsData were collected on the standardized assessment of molecular response in the context of real-life practice. BCR-ABL1 transcript levels after>2years of TKI therapy were evaluated for DMRby local laboratories as well as standardized EUTOS laboratories. Since standardized molecular monitoring is a prerequisite for treatment discontinuation, central surveillance of the performance of the participating laboratories was carried out.ResultsBetween 2014 and 2017, 3377 peripheral blood samples from 1117 CML patients were shipped to 11 standardized reference laboratories in six European countries. BCR-ABL1 transcript types were b3a2 (41.63%), b2a2 (29.99%), b2a2/b3a2 (3.58%) and atypical (0.54%). For 23.72% of the patients, the initial transcript type had not been reported. Response levels (EUTOS laboratory) were: no MMR, n=197 (6.51%); MMR, n=496 (16.40%); MR4, n=685 (22.64%); MR4.5, n=937 (30.98%); MR5, n=710 (23.47%). With a Cohen's kappa coefficient of 0.708, a substantial agreement between EUTOS-certified and local laboratories was shown.ConclusionsMulticenter DMR assessment is feasible in the context of real-life clinical practice in Europe. Information on the BCR-ABL1 transcript type at diagnosis is crucial to accurately monitor patients' molecular response during or after TKI therapy.

BCR-ABL translocation is a key hallmark of chronic myeloid leukemia (CML). The chemistry involves transcription of a novel 8.5 kb mRNA with a b3a2 and/ or b2a2 junction. Though there is an improvement in survival using the TKIs, there are causes for the treatment failures. Thus, the study focuses on the causes underlying the failed response. This study comprises BCR-ABL expression in correlation with age, gender and transcript type and disease monitoring in follow-up samples. Eighty-seven chronic phase CML patients were enrolled in the study. Out of these 24 patients were followed further. Quantitative Real time PCR was performed to assess the BCR-ABL expression followed by gel electrophoresis of PCR products. The results were expressed as CN/mu g RNA. The results obtained were correlated with SPSS 16.0 software. We found three different types of the expression that includes b2a2, b3a2 and co-expression (b2a2 + b3a2). Higher incidence of b2a2 with a relatively equal incidence of co-expression was observed. The BCR-ABL expression was higher in males, in young patients and in those exhibiting co-expression of the transcripts. Greater relapse was seen in females and in older patients. The patients with co-expression of transcripts exhibited the highest expression; however these patients showed the best treatment response suggest the co-expression is the favourable parameter for CML patients. The transcript type and BCR-ABL expression are well correlated and hence can be considered as a prognostic as well as the predictive indicator considering the BCR-ABL expression for CML patients.