Current Recommendations by the ELN Expert Panel on AML Diagnosis Management

In terms of AML diagnosis, a number of tests can currently be performed to clarify the biology of the disease.

Basic diagnostic procedure for determining myeloid malignancy

• Complete blood count examination, including differential count, with ≥ 200 nuclear cells counted in the smear.
• Aspiration of bone marrow, with a breakdown of 500 nuclear cells in the smear − myeloblasts, monoblasts, and megakaryoblasts are included in the blast tally. Monoblasts and promonocytes (but not abnormal monocytes) are counted in AML with monocytic or myelomonocytic differentiation as equivalent to blasts.
• Bone marrow trepanobiopsy – in case of dry aspiration.
• Multiparametric flow cytometry immunophenotypic assessment, which allows identification of surface and intracellular markers. It is also crucial to find the leukemia-associated immunophenotype for further MRD tracking.
• If bone marrow aspiration is not possible and circulating blasts are absent, the myeloid phenotype can be confirmed by immunohistochemical examination of the bone marrow biopsy.
• Detailed demographic data, personal history including comorbidities and medications, potential exposure to toxic substances, other toxins (including smoking), previous malignancies and their therapy. Family history (focusing on myeloid malignancies to exclude germline predisposition) and patient bleeding history evaluation are also important, as this may be related to platelet disorders (and potentially germline predisposition to malignancy).

Genetic testing

• Cytogenetic testing, possibly including detection of specific abnormalities by fluorescent in situ hybridization (FISH).
• Screening for gene mutations associated with diagnosis and identification of potential therapeutic targets:
  • FLT3 – mutation screening including identification of internal tandem duplications (ITD) and tyrosine kinase domain (TKD) mutations. Longer FLT3-ITD rearrangements may not be detectable by next-generation sequencing (NGS), so capillary electrophoresis is recommended;
  • IDH1, IDH2;
  • NPM1;
  • CEBPA (including mutation specification, as only some are associated with a favorable prognosis), DDX41, TP53, ASXL1, BCOR, EZH2, RUNX1, SF3B1, SRSF2, STAG2, U2AF1, ZRSR2.

Most of these results should be available within the first 3−7 days.

• Screening for gene rearrangements and fusions:
  • PML::RARA, CBFB::MYH11, RUNX1::RUNX1T1, rearrangements of KMT2A, BCR::ABL1, other fusion genes, if detectable.
• Additional potential tests may include the following genes: ANKRD26, BCORL1, BRAF, CBL, CSF3R, DNMT3A, ETV6, GATA2, JAK2, KIT, KRAS, NRAS, NF1, PHF6, PPM1D, PTPN11, RAD21, SETBP1, TET2, WT1.
• If germline predisposition is suspected, it is very important to test a panel of genes that include known predisposition genes.
• For certain mutations (NPM1, CBF), it is recommended to perform quantitative polymerase chain reaction (qPCR) or droplet digital PCR (ddPCR) to facilitate MRD monitoring.

Additional appropriate procedures

• Detailed examination of the overall condition, including performance status assessment (PS ECOG/WHO score).
• Biochemical testing and coagulation tests.
• Testing for hepatitis A, B, C, and HIV, serologic testing for herpes viruses (EBV, CMV, HSV, VZV).
• For women of childbearing age, pregnancy exclusion.
• Assessment of suitability for allogeneic hematopoietic stem cell transplantation and HLA typing, possibly arranging sibling testing.
• Imaging methods including chest and heart X-rays, heart assessment (ECG, ECHO).
• Information on possible cryopreservation of sperm and oocytes for people of reproductive age.
• Storage of blood, bone marrow, or other tissue samples (e.g., skin biopsy) to differentiate between germline and somatic mutations. Signing informed consents for possible additional testing on preserved samples is also crucial.

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Source: Döhner H., Wei A. H., Appelbaum F. R. et al. Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN. Blood 2022 Sep 22; 140 (12): 1345−1377, doi: 10.1182/blood.2022016867.

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