PhD Scientific Days 2021

PO_I_P: Pathology and Oncology I. Posters

Comprehensive Mutation Screening by Targeted Next-Generation Sequencing of Patients with Normal Karyotype Acute Myeloid Leukemia

Text of the abstract

Introduction: Acute myeloid leukemia (AML) is a genetically heterogeneous clonal malignancy characterized by broad spectrum of genetic alterations and a 5-year mortality rate of 75%. Conventional cytogenetics remain one of the most important prognostic factors in AML, though 40-50% of patients have normal karyotype (NK). These cases are conventionally classified as intermediate-risk, however, the clinical outcomes are highly variable.
Aim: To establish the mutational profiles of 94 AML patients with normal karyotype diagnosed in our institute between 2006 and 2019 using targeted next-generation sequencing (NGS) to detect prognostically relevant mutations according to the ELN-2017 risk classification.
Methods: Diagnostic samples were obtained from bone marrow (n=83) or peripheral blood (n=11) of patients newly diagnosed with NK AML. Median age at diagnosis was 61 years (range 26-84). Median follow up time was 11.5 months (range 0.1-121.0) with a 5-year OS of 20.5%. Targeted NGS analysis of 54 genes recurrently altered in myeloid malignancies was performed using the TruSight Myeloid Gene Panel (Illumina) with the libraries sequenced on a NextSeq500 instrument (Illumina). The allelic ratio of FLT3 ITD to wild-type FLT3 was determined by PCR and fragment analysis.
Results: NGS revealed a total of 345 somatic variants in 94 diagnostic samples with an average allelic depth of 7400x. On average, 3.7 mutations (range: 0-19) were detected per sample, with an average variant allele frequency of 33.1% (range: 5.0-96.3%), and with four patients presenting with wild-type genotype for all 54 genes analyzed. The most frequently mutated genes included NPM1 (35%), DNMT3A (31%) and FLT3 (28%) in accordance with the literature, while poor prognostic markers (ASXL1, RUNX1, TP53 mutations) were detected in 28.7% of patients. In our cohort, potentially actionable mutations were identified in 53.0% of patients. Risk classification according to ELN-2017 criteria re-assigned 57.4% of patients into a more favorable or, more commonly, a more adverse-risk group compared with the ELN-2010 criteria.
Conclusion: Targeted NGS seems to be an efficient, high-throughput assay for the genomic characterization of patients with NK AML, that enables more accurate risk assessment and identification of actionable mutations.
Funding: SGA No. 739593, EFOP-3.6.3-VEKOP-16-2017-00009, FK20_134253

University and Doctoral School

Semmelweis University, Károly Rácz Doctoral School of Clinical Medicine