Technical Aspects of Flow Cytometry-based Measurable Residual Disease Quantification in Acute Myeloid Leukemia: Experience of the European LeukemiaNet MRD Working Party

Abstract

Measurable residual disease (MRD) quantified by multiparameter flow cytometry (MFC) is a strong and independent prognostic factor in acute myeloid leukemia (AML). However, several technical factors may affect the final read-out of the assay. Experts from the MRD Working Party of the European LeukemiaNet evaluated which aspects are crucial for accurate MFC-MRD measurement. Here, we report on the agreement, obtained via a combination of a cross-sectional questionnaire, live discussions, and a Delphi poll. The recommendations consist of several key issues from bone marrow sampling to final laboratory reporting to ensure quality and reproducibility of results. Furthermore, the experiences were tested by comparing two 8-color MRD panels in multiple laboratories. The results presented here underscore the feasibility and the utility of a harmonized theoretical and practical MFC-MRD assessment and are a next step toward further harmonization.

Real-World Experience of Measurable Residual Disease Response and Prognosis in Acute Myeloid Leukemia Treated with Venetoclax and Azacitidine

“…While flow cytometry is highly applicable in more than 90% of AML cases [ 26 ], there is limited harmonization and standardization which may limit sensitivity and specificity in real-world settings [ 11 ]. Assessment of MRD at our centers utilized an eight-color Euroflow platform that incorporates the markers recommended in the recent ELN consensus document for MFC MRD assessment in AML [ 27 , 28 ]. Clinicians graded MRD using both LAIP and DfN approaches.…”

Application of precision medicine in clinical routine in haematology—Challenges and opportunities

“…FC is widely used in most haematological malignancies [106] and measures protein markers at the surface of individual malignant cells and often a fresh bone marrow sample is required. Immunophenotypic evaluation by multiparameter FC can detect one malignant cell in 10 3 –10 5 normal cells [107], as it uses a combination of leukaemic specific markers. The advantages of FC methods include its fast turnaround time, within 1 day, but it requires skilled pathologists and standardised procedures.…”

Clinical Impact of Measurable Residual Disease in Acute Myeloid Leukemia

“…In line with ELN, NCCN, and American Society of Clinical Oncology guidelines, most centers use a combination of methods—including bone marrow morphology, cytogenetics, fluorescence in situ hybridization (FISH), immunophenotyping, and molecular studies—to optimize AML diagnostics and MRD technique sensitivity, specificity, and applicability [ 10 , 13 , 14 , 15 ]. Among these techniques, the most commonly used MRD detection tool is immunophenotyping with multiparameter flow cytometry (MFC) [ 1 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. ELN guidelines provide guidance regarding flow cytometry settings, the recommended panel of cell population identifiers, and gating strategy [ 22 ].…”

“…Among these techniques, the most commonly used MRD detection tool is immunophenotyping with multiparameter flow cytometry (MFC) [ 1 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. ELN guidelines provide guidance regarding flow cytometry settings, the recommended panel of cell population identifiers, and gating strategy [ 22 ]. The two primary methods of MFC interpretation are known as leukemia-associated immunophenotype (LAIP) and different from normal (DfN) [ 23 ].…”