Evaluation of new markers for minimal residual disease monitoring in B-cell precursor acute lymphoblastic leukemia: CD73 and CD86 are the most relevant new markers to increase the efficacy of MRD 2016; 00B: 000-000.

Abstract

Multiparametric flow cytometry (MFC) is a popular technique for minimal residual disease (MRD) analysis. However, its applicability is still limited to 90% of B-cell precursor acute lymphoblastic leukemia (BCPALL) due to two major issues, i.e. a proportion of cases do not express adequate leukemia associated immunophenotype (LAIPs) with currently used markers and drug-induced antigen modulation. Hence, the incorporation of additional reliable markers is required for the further improvement of MFC-based MRD evaluation. We studied the utility of new markers in improvising MFC-based MRD detection in BCPALL. Expression-patterns of six new markers, i.e. CD24, CD44, CD72, CD73, CD86, and CD200 were studied in leukemic-blasts from ninety childhood BCPALL patients and in hematogones from 20 uninvolved staging bone marrow (BM) and ten postinduction non-BCPALL BM samples using eight-color MFC. The utility of these new markers in the day 35 postinduction MRD evaluation was determined. Frequencies of LAIPs of CD73, CD86, CD72, CD44, CD200, and CD24 in diagnostic samples were 76.7, 56.7, 55.6, 50, 28.9, and 20%, respectively. Differential expression of all new markers was highly significant (P<0.01) between early (CD10+ CD19+ CD34+) hematogones, late (CD10+ CD19+ CD34-) hematogones and BCPALL blasts except between early hematogones and BCPALL blasts for CD200 (P=0.1). In MRD-positive samples, CD73 showed the maximum (83%) frequency of LAIP and CD86 showed the highest (100%) stability of aberrant expression. Inclusion of CD73 and CD86 increased the applicability of MFC-MRD assay to 98.9% MRD samples. CD73 and CD86 are the most relevant markers to incorporate in the routine MRD evaluation of BCPALL. © 2016 International Clinical Cytometry Society.