SelliahICCS19.pdf

ICCS 2019 -- Multiple Myeloma (MM) is a cancer formed by malignant plasma cells (PC). Many MM patients are achieving complete remission with advancement in cancer therapies. As a result, quantification of measurable/minimal residual disease (MRD) is becoming increasingly important as an independent predictor of progression-free and overall survival. Moreover, MRD assessment by flow cytometric methodology has the potential to become a surrogate end-point for overall survival in MM clinical trials. EuroFlow Consortium has established a strategy to achieve high sensitivity detection of MRD in MM patients with standardized approach for sample processing and data analysis. This assay is an eight-color, two tubes, lyse/wash with intracellular staining for cytoplasmic kappa and lambda chains along with CD19, CD27, CD38, CD45, CD56, CD81, CD117, and CD138. Objective was to validate the assay for clinical sample testing and develop a set of QCs that monitor sample processing, staining and assay trending. Validation was performed with bone marrow from apparently healthy donors spiked with cryopreserved MM bone marrow mono nuclear cells (BMMC). Two different QC materials were selected: IMMUNO-TROL cells, and Veri-Cells MM QC (to monitor the abnormal PC phenotype). Veri-Cells MM QC was custom made by combining KMS-26 cell line with whole blood from an apparently healthy volunteer (from BioLegend). Precision was monitored by analyzing both QC (n=4) and samples (n=4) in triplicates in 4 independent runs and on two instruments. Overall performance was assessed with mean % CV (coefficient of variation) of all four runs (QC) and all four samples. The high assay sensitivity required for MRD evaluation is achieved by processing a large number of cells (~10 million) and acquiring a minimum of 5 million events per tube. Data were analyzed using the Infinicyt Software (Cytognos SL) which allows the combination of both assay tubes to identify normal and abnormal cell populations.