P504: CLINICAL MUTATIONAL ANALYSIS BY NEXT-GENERATION SEQUENCING AND REAL-LIFE VALIDATION OF THE REVISED 2017 EUROPEAN LEUKEMIANET GENETIC RISK STRATIFICATION IN AML PATIENTS

Abstract

Background: Recently, a census of mutated genes in AML has been described but their value in clinical practice is not fully elucidated. The revised 2017 European LeukemiaNet (ELN) recommendations for genetic risk stratification of AML have been widely adopted, but have not yet been validated in large cohorts of AML patients in real life. Aims: The objective of this work is to analyze the mutations detected by Next Generation Sequencing (NGS) and to study whether the application of ELN 2017 scale improves prognostic risk stratification with respect to ELN 2010 and Medical Research Council (MRC). Methods: We included 112 adult AML patients diagnosed in our center between Jun2017 and Dec2021 and who were studied at diagnostic using the spanish PLATFOLMA PETHEMA. The prognostic risk was established according to MRC, ELN2010 and ELN2017 classification. Baseline demographic, disease characteristics, treatment procedures and mutations by functional groupsare summarized in Table 1 NPM1 and FLT3-ITD were determined by melting curve analysis and standard PCR-EC technique according to Thiede et al (Blood 2002) in ABI 3130 Analyzer (Thermofisher). For NGS, the commercial panel Myeloid SolutionTM (Sophia Genetics) KAPA Kit amplification libraries and sequencing on ILUMINA Myseq platform were used. Variant analysis was performed using DDM software (Sophia Genetics). Results: The majority of the patients (97.1%) had at least one mutation at diagnosis detected by NGS. The median number of mutations was 2.36 (0-6). Grouped by functional groups, the most frequent were those related to DNA methylation (44.6 %) and signaling/kinase pathways (37.5%). The most prevalent were FLT3 (29 %), IDH1/IDH2 (27%) and TP 53 (19.6%) followed by NPM1 and RUNX-1 (17%). Patients older than 60 years, presented higher percentage of unfavorable ASXL1 (18.6%), RUNX1 (20%) and TP53 (25.7%) mutations with respect to younger (4.8%, 11.9% and 9.5 %) being these differences statistically significant in ASXL 1 and TP 53 (χ2 p=0.044 and p=0.047 respectively). NPM1 (28.6%) and FLT3 (40.5%) mutations were significantly more frequent in younger patients (χ2 p=0.017 and p=0.013 respectively), than in >60 years (10% and 17.1%, respectively). Re-stratifying according to ELN 2017, the 53% of patients categorized within the intermediate risk group according to MRC change prognostic group: 28.9% became redefined as unfavorable risk and 24.1% as favorable. In the overall series the overall survival analysis shows statistically significant differences taking into account either ELN 2017 or ELN 2010 and MRC (T.logrank p=0.003, p=0.018 and p=0.012, respectively). However, according to ELN 2017 there are greater differences between intermediate and unfavorable groups than in the other classifications. Statistically significant differences in overall survival according to ELN 2017 (T.logrank p=0.028) are also found in patients receiving intensive treatment. The estimated overall survival at two years is 72.%, 52.1% and 46.8% in the favorable, intermediate and unfavorable group, respectively. Image:Summary/Conclusion: - NGS proves its usefulness by detecting more clinically relevant alterations than conventional cytogenetic techniques and PCR, and stratifies a larger group of patients as favorable and unfavorable. - Our results validate the prognostic significance of the ELN2017 classification in real life, both in the overall series and in candidates for intensive QT. - ELN 2017 establishes greater survival differences between the intermediate and unfavorable group than ELN 2010 and MRC redefining the intermediate group.