Flow cytometric minimal residual disease assessment in B-cell precursor acute lymphoblastic leukaemia patients treated with CD19-targeted therapies - a EuroFlow study

The standardized EuroFlow protocol, including CD19 as primary B-cell marker, enables highly sensitive and reliable minimal residual disease (MRD) assessment in B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) patients treated with chemotherapy. We developed and validated an alternative gating strategy allowing reliable MRD analysis in BCP-ALL patients treated with CD19-targeting therapies. Concordant data were obtained in 92% of targeted therapy patients who remained CD19-positive, whereas this was 81% in patients that became (partially) CD19-negative. Nevertheless, in both groups median MRD values showed excellent correlation with the original MRD data, indicating that, despite higher interlaboratory variation, the overall MRD analysis was correct.

Automated summary

The standardized EuroFlow protocol with CD19 as the primary B-cell marker allows for sensitive and reliable MRD assessment in BCP-ALL patients undergoing chemotherapy. An alternative gating strategy has been developed for analyzing MRD in patients treated with CD19-targeting therapies, showing high concordance with original MRD data despite variations. This indicates that overall MRD analysis remains accurate even with differences in CD19 expression.