Abstract
Acute myeloid leukemia (AML) is a highly heterogeneous disease showing dynamic clonal evolution patterns over time. Various subclones may be present simultaneously and subclones may show a different expansion pattern and respond differently to applied therapies. It is already clear that immunophenotyping and genetic analyses may yield overlapping, but also complementary information. Detailed information on the genetic make-up of immunophenotypically defined subclones is however scarce. We performed error-corrected sequencing for 27 myeloid leukemia driver genes in 86, FACS-sorted immunophenotypically characterized normal and aberrant subfractions in 10 AML patients. We identified three main scenarios. In the first group of patients, the two techniques were equally well characterizing the malignancy. In the second group, most of the isolated populations did not express aberrant immunophenotypes but still harbored several genetic aberrancies, indicating that the information obtained only by immunophenotyping would be incomplete. Vice versa, one patient was identified in which genetic mutations were found only in a small fraction of the immunophenotypically defined malignant populations, indicating that the genetic analysis gave an incomplete picture of the disease. We conclude that currently, characterization of leukemic cells in AML by molecular and immunophenotypic techniques is complementary, and infer that both techniques should be used in parallel in order to obtain the most complete view on the disease.
Highlights
Acute myeloid leukemia (AML) is a highly heterogeneous clonal disease
Granulocytes were less represented in the thawed samples, but no large differences were found between leukemia-associated immunophenotypes (LAIPs) that were present in the samples analyzed at the moment of diagnosis, before Ficoll and freezing was performed, compared to the spectrum and size of LAIP populations analyzed in the corresponding frozen samples, indicating that no preferential loss of particular LAIPs occurred during freeze-thawing (Figs. 1, 2, 3, and 4)
In nine of the ten AML cases, at least one genetic mutation was present at a variant allele frequency (VAF) of approximately 50% within the isolated LAIP clones, indicating a good correlation between the aberrant genotype and phenotype
Summary
Acute myeloid leukemia (AML) is a highly heterogeneous clonal disease. Heterogeneity is observed between and within patients morphologically, immunophenotypically, and genetically [1, 2] and different responses can be observed to the applied treatments. Immunophenotyping allows the detection of leukemic cell (sub)populations. When compared to healthy cells, malignant cells can be. Annals of Hematology (2022) 101:571–579 compared to diagnosis. DfN cell detection can be used in MRD settings, especially when there is no immunophenotypic data from the moment of diagnosis or when there were no LAIPs detected at diagnosis. Genetic analyses by cytogenetics and sequencing of leukemia-associated genes may reveal pathogenic genetic aberrations in the majority of AML cases, which are used for prognostic risk categorization and the choice of personalized, targeted therapies [6,7,8]
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