Immunophenotypic studies of monoclonal gammopathy of undetermined significance

Negative impact of immunoparesis in response to anti-SARS-CoV-2 mRNA vaccination of patients with multiple myeloma

Multiple myeloma reduces cellular and humoral immunity. Optimal prediction of antibody response to anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in patients with MM and related disorders is essential to prevent coronavirus disease 2019 (COVID-19) during the SARS-CoV-2 pandemic. This study analyzed the humoral response to the anti-SARS-CoV-2 messenger ribonucleic acid (mRNA) vaccine and its associated factor in 83 patients from June to November 2021 at seven member institutions of the Kyoto Clinical Hematology Study Group. SARS-CoV-2 neutralizing antibody (nAb) was measured from 12 to 210 days. The result revealed that 40 (48.2%) patients with MM and 59 (100%) healthy controls became seropositive after vaccination. Receiver operating characteristic curve analysis identified serum immunoglobulin (Ig) M of > 18 mg/dL at vaccination as the optimal threshold level associated with seropositivity in the whole cohort. Moreover, the multivariate analysis identified serum IgM of > 18 mg/dL as the independent predictor for a favorable response. Serum IgA level was positively associated with vaccine response in a sub-cohort. Our findings indicate a significant association between immunoparesis and impaired humoral response against mRNA vaccination, including that against SARS-CoV-2, and that serum non-M-protein Ig levels can serve as surrogate biomarkers of nAb production ability.

MicroRNAs as a Potential New Preventive Approach in the Transition from Asymptomatic to Symptomatic Multiple Myeloma Disease

Simple Summary

Multiple myeloma (MM) is the second most common haematologic malignancy, and it remains an incurable disease despite the advances of novel therapies. It is characterised by a multistep process that arises from a pre-malignant asymptomatic status-defined monoclonal gammopathy of undetermined significance (MGUS), evolves to a middle stage named smouldering myeloma phase (SMM), and culminates in the active disease (MM). Identification of early and non-invasive markers of the disease progression is currently an active field of investigation. In this review, we discuss the role and significance of microRNAs (miRNAs) as potential diagnostic biomarkers to predict the clinical transition from MGUS/SMM status to MM.

Abstract

Multiple myeloma (MM) is a hematological malignancy characterised by proliferation of clonal plasma cells (PCs) within the bone marrow (BM). Myelomagenesis is a multi-step process which goes from an asymptomatic phase, defined as monoclonal gammopathy of undetermined significance (MGUS), to a smouldering myeloma (SMM) stage, to a final active MM disease, characterised by hypercalcemia, renal failure, bone lesions anemia, and higher risk of infections. Overall, microRNAs (miRNAs) have shown to significantly impact on MM tumorigenesis, as a result of miRNA-dependent modulation of genes involved in pathways known to be crucial for MM pathogenesis and disease progression. We aim to revise the literature related to the role of miRNAs as potential diagnostic and prognostic biomarkers, thus highlighting their key role as novel players within the field of MM and related premalignant conditions.

Serum exosomal microRNAs as novel biomarkers for multiple myeloma

Accumulating studies have focused on circulating microRNAs, which might be potential biomarkers for different malignancies. The aim of this study was to investigate the potential of serum exosomal microRNAs to be novel serum biomarkers for smouldering myeloma (SMM) or even multiple myeloma (MM). The levels of serum exosomal microRNAs and serum circulating microRNAs were measured in healthy individuals and patients with SMM (n = 20) or MM (n = 20). Serum exosomal microRNAs and serum circulating microRNAs were extracted from serum, and the expression levels of selected microRNAs were quantified by real-time polymerase chain reaction (PCR). The levels of serum exosome-derived miR-20a-5p, miR-103a-3p, and miR-4505 were significantly different among patients with MM, patients with SMM, and healthy individuals, while there were differences in the levels of let-7c-5p, miR-185-5p, and miR-4741 in patients with MM relative to those in SMM patients or healthy controls. Additionally, a significant correlation was rarely found between the levels of serum and exosomal microRNAs. This study shows that serum exosomal microRNAs can be used independently as novel serum biomarkers for MM.

Flow cytometric aberrancies in plasma cell myeloma and MGUS - correlation with laboratory parameters

BACKGROUND

Multiparametric flow cytometry is a useful tool for diagnosis of plasma cell (PC) dyscrasias and assessment of minimal residual disease in plasma cell myeloma (PCM). However, the immunophenotypic differences between the clonal PCs of PCM and those of monoclonal gammopathy of undetermined significance (MGUS) as well as the correlation of these flow cytometric markers with pertinent laboratory parameters have not been evaluated.

METHODS

We retrospectively identified all newly diagnosed treatment-naive PCM and MGUS patients between 09/2014 and 06/2015 who underwent 10-color flow-cytometric evaluation: CD45, CD38, CD138, cKappa, cLambda, CD19, CD27, CD28, CD56, CD117. FACSDiva analysis was used to identify antigenic aberrancies and associations with pertinent laboratory parameters were evaluated.

RESULTS

All cases demonstrated at least two aberrancies. There was a trend toward a greater number of aberrancies in PCM, with 68% showing >/= 4 aberrancies compared with 44% in MGUS (P = 0.11). The only marker more frequently aberrant in one disease class was CD19, aberrant in 68% of PCM and 25% of MGUS (P < 0.01). In PCM, significant associations were found for CD56 non-aberrancy (P = 0.05) and the presence of amyloid and CD27 aberrancy and normal serum albumin (P = 0.05). In MGUS, CD117 expression was associated with normal hemoglobin (P = 0.03).

CONCLUSIONS

The PCs of PCM show a trend toward more antigenic aberrancy than those of MGUS. There is significant association between the antigenic profiles of PCM/MGUS and clinical parameters including amyloidosis, albumin level, and hemoglobin. © 2018 International Clinical Cytometry Society.

Current applications of multiparameter flow cytometry in plasma cell disorders

Multiparameter flow cytometry (MFC) has become standard in the management of patients with plasma cell (PC) dyscrasias, and could be considered mandatory in specific areas of routine clinical practice. It plays a significant role during the differential diagnostic work-up because of its fast and conclusive readout of PC clonality, and simultaneously provides prognostic information in most monoclonal gammopathies. Recent advances in the treatment and outcomes of multiple myeloma led to the implementation of new response criteria, including minimal residual disease (MRD) status as one of the most relevant clinical endpoints with the potential to act as surrogate for survival. Recent technical progress led to the development of next-generation flow (NGF) cytometry that represents a validated, highly sensitive, cost-effective and widely available technique for standardized MRD evaluation, which also could be used for the detection of circulating tumor cells. Here we review current applications of MFC and NGF in most PC disorders including the less frequent solitary plasmocytoma, light-chain amyloidosis or Waldenström macroglobulinemia.

Role of Flow Cytometry in the Diagnosis and Prognosis of Plasma Cell Myeloma

This article provides an overview of the role of flow cytometry in the diagnosis and follow-up of plasma cell myeloma. A brief introduction to the general immunophenotypic features of normal and myeloma plasma cells is provided, followed by a discussion of technical issues as they relate to the application of flow cytometry in this entity. The prognostic and therapeutic utility of flow cytometric immunophenotyping in myeloma is also analyzed, with an emphasis on the growing role of minimal residual analysis as potential biomarker for evaluating treatment efficacy and for tailoring risk-adapted treatment, in prospective clinical trials.

Immunotherapies targeting CD38 in Multiple Myeloma

Recently, the monoclonal antibody daratumumab was approved as a single agent for the treatment of patients with relapsed/refractory Multiple Myeloma (MM). Daratumumab is an antibody targeting surface molecule CD38 on myeloma cells and the agent is already widely being used based on its good tolerability and proven efficacy. We believe, however, that the efficacy of this drug and other anti-CD38 monoclonal antibodies can be further improved by combining it with other types of immunotherapies. Furthermore, surface molecule CD38 can be used as a target for immunotherapies other than just naked monoclonal antibodies. In this report, we review the expression pattern of CD38 among normal tissues and in different types of plasma cell dyscrasias including their progenitor cells, minimal residual disease, and circulating tumor cells. We summarize the physiological role of CD38 as well as its role in the pathophysiology of MM and we present the most recent clinical trials using CD38 as a target. In addition, we highlight possible combination immunotherapies incorporating anti-CD38 monoclonal antibodies and we demonstrate alternative immunotherapeutic approaches targeting the same antigen such as CD38-specific chimeric antigen receptor (CAR) T cells.

Aberrant Levels of miRNAs in Bone Marrow Microenvironment and Peripheral Blood of Myeloma Patients and Disease Progression

The bone marrow (BM) microenvironment of multiple myeloma (MM) is reported to play a role in the biology of disease. In this study, we found that the extracellular BM microenvironment in MM contains a unique miRNA signature detectable by miRNA microarray and quantitative real-time PCR, which is partially represented in the peripheral blood. Eleven miRNAs were significantly decreased in both BM and serum of MM patients in comparison with controls. Evaluation of these miRNAs in plasma of a separate cohort of MM patients and controls confirmed significantly aberrant levels of let-7a, let-7b, let-7i, miR-15b, miR-16, and miR-20a in both serum and plasma. We then studied the myeloma precursor diseases and found that a subset of the MM miRNAs exhibited aberrant expression in monoclonal gammopathy of undetermined significance and smoldering myeloma. miRNA analysis of enriched CD138(+) plasma cells from MM and monoclonal gammopathy of undetermined significance found that most of the validated MM BM signature miRNAs were significantly decreased in MM plasma cells. Gene expression profiling indicated that multiple targets of the decreased miRNAs found increased expression in MM plasma cells, including ATF2, HRAS, HDAC4, TGFB1, TGFBR1, and mitogen-activated protein kinases. The findings suggest that these miRNAs are detectable in aberrant levels in the peripheral blood of patients with plasma cell proliferation and may play a role in aberrant plasma cell proliferation and disease progression.

Immune defects in the risk of infection and response to vaccination in monoclonal gammopathy of undetermined significance and multiple myeloma

The plasma cell proliferative disorders monoclonal gammopathy of undetermined significance (MGUS) and malignant multiple myeloma (MM) are characterized by an accumulation of transformed clonal plasma cells in the bone marrow and production of monoclonal immunoglobulin. They typically affect an older population, with median age of diagnosis of approximately 70 years. In both disorders, there is an increased risk of infection due to the immunosuppressive effects of disease and conjointly of therapy in MM, and response to vaccination to counter infection is compromised. The underlying factors in a weakened immune response in MGUS and MM are as yet not fully understood. A confounding factor is the onset of normal aging, which quantitatively and qualitatively hampers humoral immunity to affect response to infection and vaccination. In this review, we examine the status of immune alterations in MGUS and MM and set these against normal aging immune responses. We focus primarily on quantitative and functional aspects of B-cell immunity. Furthermore, we review the current knowledge relating to susceptibility to infectious disease in MGUS and MM, and how efficacy of conventional vaccination is affected by proliferative disease-related and therapy-related factors.

Immunophenotypic characterization and quantification of neoplastic bone marrow plasma cells by multiparametric flow cytometry and its clinical significance in Korean myeloma patients

Multiparametric flow cytometry (MFC) allows discrimination between normal and neoplastic plasma cells (NeoPCs) within the bone marrow plasma cell (BMPC) compartment. This study sought to characterize immunophenotypes and quantitate the proportion of NeoPCs in BMPCs to diagnose plasma cell myeoma (PCM) and evaluate the prognostic impact of this method. We analyzed the MFC data of the bone marrow aspirates of 76 patients with PCM and 33 patients with reactive plasmacytosis. MFC analysis was performed using three combinations: CD38/CD138/-/CD45; CD56/CD20/CD138/CD19; and CD27/CD28/CD138/CD117. The plasma cells of patients with reactive plasmacytosis demonstrated normal immunophenotypic patterns. Aberrant marker expression was observed in NeoPCs, with negative CD19 expression observed in 100% of cases, CD56+ in 73.7%, CD117+ in 15.2%, CD27- in 10.5%, CD20+ in 9.2%, and CD28+ in 1.3%. In PCM patients, more than 20% of NeoPCs/BMPCs were significantly associated with factors suggestive of poor clinical outcomes. Patients who were CD27- or CD56+/CD27-, demonstrated shorter overall survival than patients of other CD56/CD27 combinations. Our results support the clinical value of immunophenotyping and quantifying NeoPCs in PCM patients. This strategy could help to reveal poor prognostic categories and delineate surrogate markers for risk stratification in PCM patients.

CD200 expression in plasma cells of nonmyeloma immunoproliferative disorders: clinicopathologic features and comparison with plasma cell myeloma

The majority of plasma cell myelomas (PCMs) are positive for CD200, a membrane protein with immunosuppressive function. There are no flow cytometry data in the literature on plasma cell CD200 expression in other immunoproliferative disorders. Therefore we used flow cytometry to study the expression of CD200 on plasma cells in diagnostic bone marrow aspirates from 61 patients with monoclonal gammopathy of undetermined significance (MGUS) and 10 patients with lymphoplasmacytic lymphoma (LPL). For comparison, we evaluated CD200 expression in 74 PCM bone marrow biopsies. Thirty-three (54.1%) of 61 MGUS cases and 2 (20.0%) of 10 LPL cases were CD200+. Comparative clinicopathologic parameters for MGUS cases, based on CD200 expression status, showed no differences between the 2 groups. The proportion of CD200+ PCMs (73.0%) in our series was significantly higher than that of CD200+ MGUS (P = .030) and CD200+ LPL (P = .002) cases.

Six color flow cytometry detects plasma cells expressing aberrant immunophenotype in bone marrow of healthy donors

BACKGROUND

Both normal and malignant plasma cell (PC) populations can be identified using modern flow cytometry (FC) technique in multiple myeloma (MM) patients. Expression of CD19 and CD56 markers is heterogenous on bone marrow PCs of healthy individuals. Little is known about immunophenotypically aberrant (CD19-/CD56+) PCs subpopulation of healthy people.

METHODS

Using six color FC, we analyzed PCs in BM samples of 11 healthy donors (HD) and compared their immunophenotypic properties with clonal PC populations from MM patients.

RESULTS

Both immunophenotypically normal (CD19+/CD56-) and aberrant (CD19-/CD56+) PC populations could be detected in 10 of 11 HDs' BM samples and constituted the median of 60.3% (37.3-72.3) and 9.6% (0-35.7) of BM PCs, respectively. CD19, CD56, CD38, CD45, and CD20 marker expression characteristics were of little value discriminating clonal PCs of MM patients from immunophenotypically aberrant PCs of healthy donors.

CONCLUSIONS

Our findings suggest that aberrant immunophenotype is common in BM PCs of healthy people. Improvements in FC methodology to separate normal and malignant PCs remain an open area for future investigations.

Utility of flow cytometry immunophenotyping in multiple myeloma and other clonal plasma cell-related disorders

In recent years, multiparameter flow cytometry (MFC) immunophenotyping has become mandatory in the clinical management of hematological malignancies, both for diagnostic and monitoring purposes. Multiple myeloma (MM) and other clonal plasma cell-related (PC) disorders should be no exception to this paradigm, but incorporation of immunophenotypic studies in the management of patients with PC disorders is still far from being routinely established in many diagnostic flow cytometry laboratories. For clonal PC disorders, MFC is of clear and established clinical relevance in: (1) the differential diagnosis between MM and other PC-related disorders; (2) the identification of high-risk MGUS and smoldering MM; (3) minimal residual disease investigation after therapy; additionally it may also be useful for (4) the definition of prognosis-associated antigenic profiles; and (5) the identification of new therapeutic targets. In this article, we review the clinical value of MFC in the study of PC disorders, with specific emphasis in those areas where consensus exists on the need to incorporate MFC into routine evaluation of MM and other clonal PC-related disorders.

Immunohistochemical analysis of NOTCH1 and JAGGED1 expression in multiple myeloma and monoclonal gammopathy of undetermined significance

Notch signaling is implicated in the pathogenesis of multiple myeloma expressing high level of active Notch proteins NOTCH1 and JAGGED1 in tumor plasma cells. We investigated expression of NOTCH1 and JAGGED1 in bone marrow trephine biopsies of 80 newly diagnosed multiple myeloma and 20 monoclonal gammopathy of undetermined significance patients using immunohistochemical methods. The number of positive tumor cells was counted per 1000 tumor cells and the intensity of staining was assessed semi quantitatively. Multiple myelomas expressed NOTCH1 in 92.31% (72/78) and JAGGED1 in 92.21% (71/77) cases. NOTCH1 staining was strong in the majority of cases (59.7%), whereas JAGGED1 was predominately weak (67.6% of cases). In contrast, both markers were negative in all monoclonal gammopathy of undetermined significance cases. However, upon progression of disease from monoclonal gammopathy of undetermined significance to multiple myeloma (seen in 4 patients), analysis of the subsequent bone marrow biopsy showed weak expression of both markers in tumorous plasma cells. Immunohistochemistry results were compared with the pattern of bone marrow infiltration, plasma cell differentiation, and the presence of t(11;14)(q13,q32), t(14;16)(q32;q23),and t(4;14)(p16.3;q23) and overall survival in multiple myeloma patients. A significant correlation was found between strong NOTCH1 staining in multiple myeloma plasma cells and the diffuse type of bone marrow infiltration (P = .002) and an immature morphologic type of plasma cells (P = .043). After a median follow-up of 20.3 months, in multiple myeloma patients no difference in overall survival between NOTCH1 (P = .484) and JAGGED1 (P = .822) positive and negative cases were found. In conclusion, our results indicate importance of NOTCH1 and JAGGED1 expression in plasma cell neoplasia and a possible diagnostic value of their immunohistochemical evaluation of bone marrow infiltrates for multiple myeloma.

The persistence of immunophenotypically normal residual bone marrow plasma cells at diagnosis identifies a good prognostic subgroup of symptomatic multiple myeloma patients

Multiparameter flow cytometry immunophenotyping allows discrimination between normal (N-) and myelomatous (MM-) plasma cells (PCs) within the bone marrow plasma cell compartment (BMPCs). Here we report on the prognostic relevance of detecting more than 5% residual normal plasma cells from all bone marrow plasma cells (N-PCs/BMPCs) by multiparameter flow cytometry in a series of 594 newly diagnosed symptomatic MM patients, uniformly treated according to the Grupo Español de MM 2000 (GEM2000) protocol. Our results show that symptomatic MM patients with more than 5% N-PCs/BMPCs (n = 80 of 594; 14%) have a favorable baseline clinical prospect, together with a significantly lower frequency of high-risk cytogenetic abnormalities and higher response rates. Moreover, this group of patients had a significantly longer progression-free survival (median, 54 vs 42 months, P = .001) and overall survival (median, not reached vs 89 months, P = .04) than patients with less than or equal to 5% N-PCs/BMPCs. Our findings support the clinical value of detecting residual normal PCs in MM patients at diagnosis because this reveals a good prognostic category that could benefit from specific therapeutic approaches. This trial was registered at www.clinicaltrials.gov as NCT00560053.

Utility of CD56 immunohistochemical studies in follow-up of plasma cell myeloma

Although 70% to 80% of plasma cell myelomas (PCMs) express CD56, few data are available on the usefulness of CD56 immunohistochemical analysis in assessing residual disease. We retrospectively reviewed 127 PCM posttreatment bone marrow (BM) specimens, classifying them as positive or negative for residual disease (independent of CD56 immunohistochemical studies) based on abnormal plasma cell (PC) morphologic features or flow cytometry (FC) and/or light chain restriction by immunohistochemical studies (conventional criteria). CD56 immunohistochemical analysis was performed on these and 20 negative lymphoma staging BM specimens. Of 127 BM specimens, 74 were positive and 53 were negative for residual PCM by conventional criteria. Of 74 BM specimens positive by conventional criteria, 59 (80%) demonstrated CD56 (strong+) PCs in clusters and/or with cytologic atypia. Of the 53 BM specimens negative by conventional criteria, 3 showed CD56 (strong+) morphologically atypical PCs in clusters or scattered. CD56 immunohistochemical analysis is useful for detecting residual PCM, particularly in morphologically equivocal cases in which light chain restriction cannot be demonstrated, and may serve as a potential response criterion.