Location and type of isocitrate dehydrogenase mutations influence clinical characteristics and disease outcome of acute myeloid leukemia

Background: Mutations of isocitrate dehydrogenase 1 and 2 are novel common genetic alterations identified in acute myeloid leukemia. Aims: To investigate the frequency, clinical associations and prognostic effect of isocitrate dehydrogenase 1 and 2 mutations together, followed by a detailed investigation of particular mutations. Methods: A consecutive cohort of 376 patients diagnosed with acute myeloid leukemia were enrolled to compare clinical characteristics. Prognostic impact was analyzed for 314 patients younger than 60 years treated with curative intention. Isocitrate dehydrogenase 1 and 2 mutations were screened using allele-specific PCR and high resolution melting, followed by a confirmatory sequencing. Results: Isocitrate dehydrogenase (IDH) 1 and 2 mutations were mutually exclusive, detected in 8.5% and 7.5% of the cases respectively. Presence of mutations was associated with older age (p=0.001), higher platelet count (p=0.001), intermediate risk karyotype (p<0.0001), nucleophosmin1 mutation (p=0.022), and with lower mRNA expression level of ABCG2 gene (p=0.006), as compared to mutation negative cases. Remission, relapse rates and overall survival were not different in IDH-mutation positive patients. Interestingly, particular mutations differred in association with nucleophosmin1 mutation: co-occurrence was observed in 14.3% of R132C vs. 70% of R132H carriers (p=0.02); and in 47.4% of R140Q vs. 0% R172K carriers (p=0.02) of IDH1 and IDH2 genes, respectively. R132H negatively influenced overall survival compared to isocitrate dehidrogenase 1 and 2 negative (p=0.02) or to R132C (p=0.019) patients. Conclusions: IDH mutations are frequent recurrent mutations in acute myeloid leukemia. Although a general common pathogenetic role is proposed, our results indicate that differences in clinical characteristics and treatment outcome may exist among disctinct mutations of both genes

Results of the European survey on the assessment of deep molecular response in chronic phase CML patients during tyrosine kinase inhibitor therapy (EUREKA registry)

Purpose: the 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 three months 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. Methods: data were collected on the standardized assessment of molecular response in the context of real life practice. BCR-ABL1 transcript levels after &gt;2 years of TKI therapy were evaluated for DMR. Since standardized molecular monitoring is a prerequisite for treatment discontinuation, central surveillance of the performance of the participating laboratories was carried out. Results: between 2014-2017, 3,377 peripheral blood samples from 1,117 CML patients were shipped to 11 standardized reference laboratories in six European countries. BCRABL1 transcript types were b3a2 (41.63%), b2a2 (29.99%), b2a2/b3a2 (3.58%) and atypical (0.54%). For 23.72% of 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 EUTOScertified and local laboratories was shown. Conclusions: multicenter 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 therap

Standardization of molecular monitoring of CML: results and recommendations from the European treatment and outcome study

Standardized monitoring of BCR::ABL1 mRNA levels is essential for the management of chronic myeloid leukemia (CML) patients. From 2016 to 2021 the European Treatment and Outcome Study for CML (EUTOS) explored the use of secondary, lyophilized cell-based BCR::ABL1 reference panels traceable to the World Health Organization primary reference material to standardize and validate local laboratory tests. Panels were used to assign and validate conversion factors (CFs) to the International Scale and assess the ability of laboratories to assess deep molecular response (DMR). The study also explored aspects of internal quality control. The percentage of EUTOS reference laboratories (n = 50) with CFs validated as optimal or satisfactory increased from 67.5% to 97.6% and 36.4% to 91.7% for ABL1 and GUSB, respectively, during the study period and 98% of laboratories were able to detect MR 4.5 in most samples. Laboratories with unvalidated CFs had a higher coefficient of variation for BCR::ABL1 IS and some laboratories had a limit of blank greater than zero which could affect the accurate reporting of DMR. Our study indicates that secondary reference panels can be used effectively to obtain and validate CFs in a manner equivalent to sample exchange and can also be used to monitor additional aspects of quality assurance. </p