Early detection of ABCB1 gene expression levels could be important for the diagnosis and monitoring of ALL patients.

The understanding of the somatic driver mutations and genetic abnormalities in acute myeloid leukemia (AML) has enabled the discovery of actionable mutations and improved risk stratification; however, it is unclear how the distribution of molecular defined subsets varies within different populations. The median age of AML diagnosis in Mexico is younger than for other international cohorts; however, no mutational analysis has been performed to date. We thus sought to ascertain differences in somatic mutations in this population. Methods: We created a collaborative research initiative to evaluate the frequency of recurrently mutated genes in 48 Mexican AML patients using a combination of whole-exome and targeted next-generation sequencing. We compared the prevalence to other reported Hispanic cohorts in the US and large international cohorts. Results: The median age of diagnosis was 38 year (15-86). Somatic mutations were detected in 96% of patients, with a median of 2 mutated genes per patient (range 0-6). The most prevalent mutations in the cohort were FLT3 (29%) (with FLT3-TKD over-represented in 21% of the total cohort vs. 10% for FLT3-ITD and 6% harboring simultaneous ITD and TKD mutations), followed by CEBPA (21%), TET2 (19%), DNMT3A (19%), RUNX1 (15%) and NPM1 (12%). Fusion genes were detected in 21% of patients, with t(8;21)(AML-ETO) being the most commonly found (13%), followed by MLL rearrangements (4%) and inv(16)(CBFB-MYH11) (2%). When compared to international cohorts, CEBPA, RUNX1 GATA2, TET2, AML1-ETO, U2AF1, ASXL1 and KIT were found to be enriched in our cohort. In contrast, mutations in FLT3-ITD, DNMT3A, NPM1 and IDH2 were under-represented in the Mexican cohort. There was an over-representation of CEBPA mutated AML, with a characteristic mutational distribution and variant allele frequencies (VAF) in the 50% range that could be indicative of a greater incidence of germline predisposition in this population. The median overall survival for the cohort was 9 months. Adjustment for prognostic variables that tend to have better prognosis, such as lower age, higher prevalence of CEBPA and lower FLT3-ITD prevalence, did not attenuate the disparities in disease outcomes. Conclusion: Mexican AML patients show a distinct genetic repertoire compared with other international cohorts that point to differences in host genetic susceptibility and environmental factors. Interestingly, some of the detected variants are targetable mutations that could influence management decisions. Despite some better prognostic risk groups such as younger age, lower FLT3-ITD and higher CEBPA, the outcomes for the cohort were overall poor, which correlates to reports of Hispanic minorities in the SEER database. Based on these findings, it is important to further investigate the true incidence of germline mutations in Mexican patients and other Hispanic patients and determine if there is a genetic susceptibility to develop AML that could explain some of the difference in age of onset and molecular findings. Citation Format: Alexandra Gomez-Arteaga, Nuria Mencia-Trinchant, Adolfo Martinez Tovar, Irma Olarte Carrillo, Anel Garcia Laguna, Etta Rozen Fuller, Christian Ramos Penafiel, Monica L. Guzman, Duane C. Hassane. Molecular landscape of acute myeloid leukemia in Mexico [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C061.

Background Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by different genetic alterations that cause changes in the normal mechanisms of differentiation, which are associated with chemoresistance. The ABCB1 gene is part of a family of ATP-binding cassette (ABC) transporter genes involved in the progression of various types of cancer. The following work aimed to evaluate the expression levels of the ABCB1 gene and the C3435T SNP with the response to first-line treatment and survival in patients with AML. Methods In total 135 samples were taken to isolate total RNA and DNA at the beginning of the treatment. Expression analysis by RT-qPCR and SNP C3435T assessment method were performed for real-time Polymerase chain reaction (qPCR). Results The expression levels impact on the survival of patients with AML compared to low or absent levels; the CC genotype was found in 22.9%, the CT genotype was found in 47.4%, and the TT genotype was found in 29.6%, the presence of the C3435T SNP, the TT genotype also impacts with a lower survival compared to CT and CC genotypes. In addition, it was shown that the dominant model significantly impacts survival. Conclusion In conclusion, we have found that the overexpression of the ABCB1 gene, as well as the presence of the TT genotype of the C3435T SNP, contributes to a worse prognosis in AML.

INTRODUCTION. The over expresión of the multidrug resistance genes (MDR) specifficaly ABCB1 and ABCG2 correlate with a poor prognosis in patients with ALL. Different drugs specially the chomotherapeutic agents are they substrates. This genes encode a family of different membrane transports that Works with energy specifically the ATP. Metformin is a biguanide whose mechanism of action is the activiation of AMPK and depletes the levels of ATP. PRIMARY OBJECTIVE: Evaluate the efficacy of the use of Metformin on the levels of expression of the MDR genes (ABCB1 y ABCG2) by RQ-PCR in ALL cell lines and patients with ALL during a preinduction treatment with prednisone. RESULTS. In vitro study . The ALL cell lines RS4, ReH, MOLT4 and SUB15 were elavluated. After the addition of Metformin (10uM) the expression level of ABCB1, ABCG2 started to decrease after the 24hrs of culture (mean expression level of 0.3823 ABCB1 and 0.4265 of ABCB2) with a máximum effect at 48 hours (0.2415 ABCB1 and 0.3452 ABCB2) The difference of levels were statystically significant (p= 0.0045). In vivo study . About 108 patients were evaluated, 44 (40.7%) in the arm of prednisone and 64 (59.3%) in the arm of prednisone plus metformin. Fort eh subanalysis of the MDR genes by RQ-PCR we select 25 patients (14 in the prednisone arm and 11 in the metformin arm). The mean levels of the genes was 0.1906 for the ABCB1 gene and 0.3371 of the ABDG2. At the moment of diagnosis about 32% were considerer with high level of expression (n=8), 28% (n=7) of low expression and 40% (n=10) do not express any of the both genes. After the treatment with Metformin 4 patients with high expression at diagnosis change the patter for low expression. Although there is no difference in means of the expression of genes in both arms (p = 0.391 , p = 0. 828) in the group of metformin the prognosis in the high expression group was better than in the prednisone arm (p=0.043). Fort he entire cohort the complete remission rate was higher in the Metformin cohort comparing with prednisone (86.4% versus 67.2%) and the refractoriness was higher in the group of prednisone (n=16, 25%) p=0.002. About the relapse, the addition of Metformin reduce the relapse rate ( 6 vs 21 patients, p = 0.027). Conclusion. The addition of metformin in a controlled enviroment reduce the expression of the MDR genes, but in vivo the impact is primarily on the refractory leukemias and the relapse rate Disclosures No relevant conflicts of interest to declare.

Efecto de la metformina en la etapa de inducción en pacientes con leucemia aguda linfoblástica y su impacto clínico en la supervivenciaEffect of metformin added to chemotherapy on the survival of patients with acute lymphoblastic leukemiaBackground: Metformin has antineoplastic and cancer protective effects in vitro, sensitizing leukemia cells to chemotherapeutic agents, inducing apoptosis and cell cycle arrest. Aim: To assess the effect of metformin on the induction stage in patients with ALL and its impact on overall survival and relapse. Material and Methods. We included 123 patients treated with metformin and without metformin. The dose used was 850 mg PO at 8 h intervals. The survival analysis was used by Kaplan-Meier method, the difference between the distinct groups was performed using the log Rank test. Results. The overall survival at a median follow up of 700 days of follow-up was 43%, with a disease-free survival of 47%. Regarding the treatment groups, patients with metformin had a lower rate of relapse compared to the group receiving only chemotherapy (6.5% vs 17.1%, p = 0.006). Conclusions. The addition of metformin to the conventional treatment of ALL was associated with an improvement in survival, this association being independent of the type of biological risk at diagnosis. (Rev Med Chile 2018; 146: 846-853)