Performance of a novel 8-color flow cytometry panel in the detection of minimal residual disease assessment of chronic lymphocytic leukemia

Background: The status of minimal residual disease (MRD) has been established as an important prognostic indicator in chronic lymphocytic leukemia (CLL). Methods Owing to the requirements of high accuracy, reproducibility and comparability of MRD, this study investigated the performance of a flow cytometric approach (CD45-ROR1 panel) in the MRD detection of CLL patients, with European Research Initiative on CLL (ERIC) 8-color panel as the “gold standard”. Results The sensitivity, specificity and concordance rate of CD45-ROR1 panel in the MRD assessment of CLL were 100% (87/87), 88.5% (23/26) and 97.3% (110/113), respectively. Two of the 3 non-consistent samples were further verified by the next-generation sequencing. In addition, the MRD results obtained from the CD45-ROR1 panel were positively associated with the ERIC 8-color results for MRD assessment (R = 0.98, p  0.1%). For the reproducibility assessment, the bias was smaller at three datapoints in the CD45-ROR1 panel as compared with that of the ERIC 8-color panel. Moreover, MRD level detected using the CD45-ROR1 panel for the same samples between different laboratories showed a strong statistical correlation (R = 0.99, p  < 0.0001) with a trivial inter-laboratory variation (bias, 0.135; 95% CI, -0.439-0.709). Interesingly, the MRD level detected in the lymph nodes samples were significantly higher than that of the peripheral blood and bone marrow samples ( p  = 0.029). Conclusions Collectively, this study demonstrates that the CD45-ROR1 panel is a reliable method for the MRD assessment of CLL, with higher sensitivity, reproducibility, and reliability.