Harmonization of Flow Cytometric Minimal Residual Disease Assessment in Multiple Myeloma in Centers of Polish Myeloma Consortium

Abstract

Minimal residual disease (MRD) status is now considered as one of the most relevant prognostic factors in multiple myeloma (MM) while MRD negativity became an important endpoint in clinical trials. Here, we report the results of the first study evaluating the reproducibility of high-sensitivity flow cytometry MM MRD assessment in four laboratories in Poland. EuroFlow protocols for instrument setting standardization and sample preparation in MM MRD assessment were implemented in each laboratory. In the inter-laboratory reproducibility study, 12 bone marrow samples from MM patients were distributed and processed in participant laboratories. In the inter-operator concordance study, 13 raw data files from MM MRD measurements were analyzed by five independent operators. The inter-laboratory study showed high 95% overall concordance of results among laboratories. In the inter-operator study, 89% of MRD results reported were concordant, and the highest immunophenotype interpretation differences with regard to expression of CD27, CD45, CD81 were noticed. We confirmed the applicability and feasibility of the EuroFlow protocol as a highly sensitive method of MRD evaluation in MM. Results of our inter-center comparison study demonstrate that the standardization of MM MRD assessment protocols is highly desirable to improve quality and comparability of results within and between different clinical trials.

Interlaboratory comparison of high-throughput protein biomarker assay quantifications for radiation exposure classification

“…In this work, we tested harmonization of fluorescence intensity values generated on ISX MkII instruments using two reference materials: blood samples prepared at CRR and commercially produced rainbow beads. While fluorescence intensity harmonization studies using VersaComp Antibody beads and rainbow beads have been previously conducted with conventional flow cytometers that use photomultiplier tube (PMT) detectors [ 10 – 12 ], to our knowledge, this study represents the first harmonization attempt on a cytometer using a Charged-Coupled device (CCD), such as an IFC which requires the adjustment of laser power to modulate the fluorescent signal intensity. Both sample and bead harmonization approaches successfully reduced the variability between the instruments ( Fig 3 ), which resulted in matched diagnostic endpoints of exposure classification on each instrument ( Fig 6 ), but they are not practically equivalent methods.…”

Role of flow cytometric measurable residual disease assessment in multiple myeloma

“…The results of a survey analyzing the method of MRD assessment in MM in Poland showed a high variability of procedures and as much as a 100-fold difference in the sensitivity achieved between different laboratories [52]. Subsequently, harmonizing cytometer parameters and assay protocols in four cytometric laboratories allowed a high, 95%, concordance of results obtained in laboratories, even in samples with very few pathological PCs [53]. This confirms the value of the NGF method and legitimizes standardization activities that ensure consistency in the interpretation of MRD assessment results, which is necessary for multicenter projects.…”

Risk Stratification Before and During Treatment in Newly Diagnosed Multiple Myeloma: From Clinical Trials to the Real-World Setting

“…Applicability of both NGS and NGF in standard clinical practice is increasing, but remains suboptimal because these techniques are not usually available in smaller centers, and not even referral centers can always routinely assess MRD ( 68 ). Worldwide efforts are being made to evaluate the reproducibility and applicability of NGF and NGS also in the real-world setting ( 69 ).…”