Multiparameter Flow Cytometry Identification of Neoplastic Subclones: A New Biomarker in Monoclonal Gammopathy of Undetermined Significance and Multiple Myeloma

Abstract

Multiparameter flow cytometry (MFC)-based clonality assessment is a powerful method of diagnosis and follow-up in monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). However, the relevance of intraclonal heterogeneity in immunophenotypic studies remains poorly understood. The main objective of this work was to characterize the different immunophenotypic subclones in MGUS and MM patients and to investigate their correlation with disease stages. An 8-color MFC protocol with 17 markers was used to identify the subclones within the neoplastic compartment of 56 MGUS subjects, 151 newly diagnosed MM patients, 30 MM subjects in complete remission with detectable minimal residual disease, and 36 relapsed/refractory MM patients. Two or more clusters were observed in > 85% of MGUS subjects, 75% of stage I MM patients, and < 15% in stage III. Likewise, a significant correlation between the dominant subclone size, secondary cytogenetic features, and changes in the expression of CD27, CD44, and CD81 was detected. The loss of intraclonal equilibrium may be an important factor related with kinetics and risk of progression not well considered to date in MFC studies. The MFC strategy used in this work can provide useful biomarkers in MGUS and MM.

Necessity of flow cytometry assessment of circulating plasma cells and its connection with clinical characteristics of primary and secondary plasma cell leukaemia

“…As the second generation of the Euroflow PCD protocol contains a restricted number of markers, combination of backbone markers with other MoAbs in Euroflow settings is possible, to cover a wide phenotypic PC profile in specific cases, such as PCL. This can further elucidate its behaviour and the clinical impact of the PCL immunophenotypic profile 33,52 …”

“…This can further elucidate its behaviour and the clinical impact of the PCL immunophenotypic profile. 33,52 Since sPCL evolves from existing MM, significantly longer median OS of pPCL than sPCL was expected. Other groups also found similar data of longer median OS in pPCL than sPCL.…”

Malignant plasmacytes in bone marrow detected by flow cytometry as a predictor for the risk stratification system of multiple myeloma

“…However the application of flow cytometry in MM is mainly used in monitoring of minimal residual disease (Flores- Montero et al, 2017;Rasche et al, 2019;Roshal, 2018;Waldschmidt et al, 2018). However, it would be most valuable to PCs and CD27, CD19 and CD56 to distinguish between normal and abnormal PCs according to existing literature (Alaterre et al, 2018;Flores-Montero et al, 2016;Tarín et al, 2019). This abnormal phenotype of BM plasma cells has been used to study minimal residual disease in MM, and it has been shown that the persistence of abnormal immunophenotype PC in BM after treatment is associated with poor clinical outcomes (Davies et al, 2002;Galtseva et al, 2018).…”

Understanding the Bioactivity and Prognostic Implication of Commonly Used Surface Antigens in Multiple Myeloma

“…Interestingly, progression from MGUS to MM is characterized by reduced sub-clones’ variability with the appearance of a dominant clone. The immunophenotype profile was similar between MGUS and MM, however loss of CD27 and an increase in CD81 was noted in the dominant clone of relapsed patients [ 93 ]. A further study linked CD81 with differentiation of MM cells and identified CD19+/CD81− expressing MM cells as a more immature subset of PC [ 94 ].…”

“…CD27 expression on T-cells acts as a co-stimulatory receptor, while binding of CD70 to CD27 on B-cells promotes differentiation to PC [ 97 ]. Several studies have shown that loss of CD27 expression characterizes progression to MM and less favorable prognosis [ 93 , 98 , 99 ]. Chu et al investigated the significance of CD27 expression in newly diagnosed MM patients and found that CD27-negative disease had higher adverse risk characteristics, including higher PC burden and advanced stage.…”