Methodological aspects of minimal residual disease assessment by flow cytometry in acute lymphoblastic leukemia: A french multicenter study

Evaluation of minimal residual disease (MRD) on the 15th day of treatment of acute lymphoblastic leukemia from B-linear precursors (B-ALL) in children is of key importance in the prognosis of the disease. When evaluating the MRD, it is necessary to take into account the features of the primary immunophenotype of tumor B-lymphoblasts. To assess the MRD on the 15th day of treatment several immunological approaches have been proposed that have a general concept, but differ in fundamentally important details. The purpose of this work was to analyze the established flow cytometry (FC) protocols of the main research groups (BerlinFrankfurt-Munster Group, St. Jude Hospital, Children’s Oncology Group) and to compare the results evaluated according to those approaches. This study was approved by the Independent Ethical Committee N.N. Blokhin National Medical Cancer Research Center. The study included 131 patients with B-ALL aged 1 to 17 years (median 5.53). Pre-Pre-B immunosubvariant prevailed (92.4%). A morphological (myelogram count) and immunological (MRD assessment) study of the BM was performed in all patients on the 15th day. Comparing the FC protocols of the MRD on the 15th day, it was shown that CD10 was a more reliable criterion for the detection of B-LP in comparison with CD34. The expression of CD45 may serve as an additional criterion for the detection of B-LP. The recalculation of the mononuclear cells is a more stringent criterion for determining the MRD. The scientific novelty is that for the first time on the 15th day, a detailed comparison of flow cytometry data with a cytological picture of the bone marrow was carried out. It was shown for the first time that not all B-LP detected on the basis of CD10+ /CD19+ /CD34+ /CD45low are aberrant according to CD58/CD38.

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Flow cytometry minimal residual disease assessment in peripheral blood of adult acute lymphoblastic leukemia patients.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e18517 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e18517-e18517

Author(s):

Alissa Minkovsky ◽

Karry Charest ◽

Ryan Schmidt ◽

Debra Briggs ◽

Daniel J. DeAngelo ◽

...

Keyword(s):

Flow Cytometry ◽

Acute Lymphoblastic Leukemia ◽

Minimal Residual Disease ◽

Peripheral Blood ◽

Residual Disease ◽

Lymphoblastic Leukemia ◽

Accurate Determination ◽

Disease Assessment ◽

Extramedullary Relapse ◽

Minimal Residual

e18517 Background: Multiparametric flow cytometry (FC) of bone marrow aspirate (BM) is a widely used method of minimal residual disease (MRD) assessment in acute lymphoblastic leukemia (ALL). In practice, ALL with hematogone-like phenotype and patients with recurrence of isolated extramedullary disease present challenges in accurate determination of MRD status. We hypothesized that addition of FC MRD of peripheral blood would aid in the interpretation of MRD status. Methods: 76 matched BM and PB specimens were analyzed independently for presence of ALL MRD by 6-color FC. Results: The overall rate of BM MRD-positivity was 24% (18/76) and PB was also MRD-positive in 22% (4/18) of BM-positive cases. PB MRD sensitivity and specificity relative to BM MRD was 13% [95% confident interval (CI) 2%-42%] and 98% [88-100%] for B-ALL samples (n = 65) and 67% [13%-98%] and 75% [36%-95%] for T-ALL samples (n = 11), respectively. We identified 2 cases with evidence of leukemic cells in PB at the time of the extramedullary relapse that were interpreted as MRD-negative in BM. Conclusions: PB MRD demonstrates high specificity with relatively low sensitivity, especially in B-ALL when compared to T-ALL. The use of combined PB and BM samples in MRD assessment by current FC methods may have added clinical and diagnostic value in patients with high risk of extramedullary relapse, including PB MRD as a non-invasive method for monitoring of systemic relapse.

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