Highly sensitive single tube B‐lymphoblastic leukemia/lymphoma minimal/measurable residual disease test robust to surface antigen directed therapy

Abstract

AbstractBackgroundMeasurement of minimal/measurable residual disease (MRD) in B‐lymphoblastic leukemia/lymphoma (B‐ALL) has become a routine clinical evaluation tool and remains the strongest predictor of treatment outcome. In recent years, new targeted anti‐CD19 and anti‐CD22 antibody‐based and cellular therapies have revolutionized the treatment of the high‐risk B‐ALL. The new treatments raise challenges for diagnostic flow cytometry, which relies on the presence of specific surface antigens to identify the population of interest. So far, reported flow cytometry‐based assays are developed to either achieve a deeper MRD level or to accommodate the loss of surface antigens post‐target therapies, but not both.MethodsWe developed a single tube flow cytometry assay (14‐color‐16‐parameters). The method was validated using 94 clinical samples as well as spike‐in and replicate experiments.ResultsThe assay was well suited for monitoring response to targeted therapies and reached a sensitivity below 10−5 with acceptable precision (coefficient of variation < 20%), accuracy, and interobserver variability (κ = 1).ConclusionsThe assay allows for sensitive disease detection of B‐ALL MRD independent of CD19 and CD22 expression and allows uniform analysis of samples regardless of anti‐CD19 and CD22 therapy.