Plasma cells expression from smouldering myeloma to myeloma reveals the importance of the PRC2 complex, cell cycle progression, and the divergent evolutionary pathways within the different molecular subgroups.

Sequencing studies have shed some light on the pathogenesis of progression from smouldering multiple myeloma (SMM) and symptomatic multiple myeloma (MM). Given the scarcity of smouldering samples, little data are available to determine which translational programmes are dysregulated and whether the mechanisms of progression are uniform across the main molecular subgroups. In this work, we investigated 223 SMM and 1348 MM samples from the University of Arkansas for Medical Sciences (UAMS) for which we had gene expression profiling (GEP). Patients were analysed by TC-7 subgroup for gene expression changes between SMM and MM. Among the commonly dysregulated genes in each subgroup, PHF19 and EZH2 highlight the importance of the PRC2.1 complex. We show that subgroup specific differences exist even at the SMM stage of disease with different biological features driving progression within each TC molecular subgroup. These data suggest that MMSET SMM has already transformed, but that the other precursor diseases are distinct clinical entities from their symptomatic counterpart.

Current and potential applications of positron emission tomography for multiple myeloma and plasma cell disorders.

Fluorine-18 (18F)-fluorodeoxyglucose (FDG) positron emission tomography (PET) allows evaluation of elevated glucose metabolism in malignancies. There has been increasing interest in FDG PET/CT for plasma cell disorders since the International Myeloma Working Group outlined multiple applications of this imaging modality, including distinguishing smoldering myeloma from active multiple myeloma, confirmation of solitary plasmacytoma, and multiple indications in patients with known multiple myeloma, including determining extent of initial disease, monitoring therapy response, and detection of residual disease following therapy. The field of molecular imaging is now shifting focus from evaluation of metabolism to targeted evaluation of specific tumor markers. Targeted PET imaging targeted of CXCR4 and CD38 has advanced into translational clinical trials, bringing us closer to powerful imaging options for myeloma. In this review we discuss the current applications of FDG PET/CT in plasma cell disorders, as well as advances in targeted PET imaging.

Eruptive ulcerative follicular spicules heralding progression of smoldering multiple myeloma.

Herein, we describe a patient with immunoglobulin G (IgG)-lambda smoldering multiple myeloma with translocation t(4:14) who developed widespread ulcerative horny-like spicules, heralding rapid progression to overt myeloma requiring aggressive chemotherapy and autologous stem cell transplantation. The serum abnormal immunoglobulin in the blood was cryoglobulin, which typically precipitates in the tissues at low temperatures causing inflammation and tissue damage. Histopathological changes, observed in lesions at different evolutionary stages, evidenced columns of horny-like eosinophilic homogeneous material, immunoreactive for IgG lambda, protruding from the dilated and/or distorted follicular openings or acrosyringia and small vessel thrombotic vasculopathy and vasculitis in concert with an inflammatory neutrophilic and lymphocytic reaction. Biochemical investigations on material from a spicule and ulcero-necrotic lesion revealed cryoprecipitates containing IgG-lambda with electrophoretic characteristics identical to those of the serum dysprotein. Our findings suggest that the formation of spicules and development of ulcerative lesions are a part of the same clinical spectrum where the cold-dependent precipitation of the immunogenic dysprotein, both in the skin vessels and hair follicle infundibula, play a major pathogenetic role. Whether this highly characteristic paraneoplastic dermatosis can identify patients with high-risk cytogenetic abnormalities and be incorporated into prognostic models, applicable early on in the course of myeloma, warrants further investigation.

PD-L1, LAG3, and HLA-DR are increasingly expressed during smoldering myeloma progression.

Symptomatic multiple myeloma (MM) is a plasma cell neoplasm that represents the final stage of a continuum of clinical conditions that start from monoclonal gammopathy of unknown significance (MGUS), then transits in the more advance, but still asymptomatic, smoldering MM (SMM), with a final evolution in symptomatic MM. To investigate SMM microenvironment modifications, we studied 16 patients diagnosed at our hospital. Eight of them (group A) developed MM within 2 years from diagnosis while the others (group B) had stable SMM. Samples were bone marrow biopsies at diagnosis and after 2 years (± 4 months) and were analyzed by immunohistochemical analysis. Firstly, we found a significant increase in both CD4+ cells (11 vs 17%, p < 0.01) and CD8+ cells (15 vs 18%, p < 0.01) between diagnosis and at follow-up samples (whole cohort). This was associated to an increase in the CD4+/CD8+ ratio (0.74 vs 0.93, p < 0.01). Secondly, we discovered an increased expression of T cell inhibitory molecules during SMM evolution. In fact, plasma cell PD-L1 and microenvironment cell LAG3 expression increased from 1 to 12% (p = 0.03) and 4 to 10% (p = 0.04), respectively, from diagnosis to follow-up. Also, plasma cells and microenvironment cells HLA-DR expression augmented during SMM evolution from 7 to 10% (p = 0.04) and 29 to 39% (p = 0.01), respectively. When comparing group A vs group B, we found an increased CD68-KP1+ cell infiltration in favor of group B at diagnosis (23 vs 28%, p = 0.01) and a greater plasma cell infiltration at follow-up (50 vs 26%, p < 0.01). Our findings suggest how immune escape mechanisms appear earlier during multiple myeloma evolution, and that LAG3 could be a possible immunologic target in this setting.

The Plasma Levels of the Angiogenic Cytokine Endocan Are Elevated in Patients with Multiple Myeloma.

BACKGROUND/AIM: Monoclonal gammopathy of unknown significance (MGUS) and smoldering multiple myeloma often precede multiple myeloma (MM). The identification of biomarkers predicting progression to MM might facilitate an earlier diagnosis of MM. Our study assessed the diagnostic value of plasma levels of endocan, a 50-kDa soluble dermatan sulfate proteoglycan produced and secreted by endothelial cells, hitherto unknown in MM, in patients with plasma cell dyscrasia. MATERIALS AND METHODS: Endocan levels were determined in 96 peripheral blood plasma samples by sandwich enzyme-linked immunosorbent assay (ELISA) in healthy controls (n=12), in patients with MGUS (n=17), and in patients newly diagnosed with (n=42) or relapsed/refractory (n=25) MM. RESULTS: Median endocan concentration increased from MGUS (315.00 pg/ml) and healthy controls (316.19 pg/ml) to newly-diagnosed MM (371.82 pg/ml; p=0.027). The low endocan levels (median=246.20 pg/ml) in patients with relapsed/refractory MM were similar to those in healthy controls and patients with MGUS. A cut-off value of >220 pg/ml endocan in peripheral blood discriminated patients newly diagnosed with MM from those with MGUS (area under the curve(AUC)=0.66, 95% confidence interval(CI)=0.55-0.81). CONCLUSION: The plasma levels of endocan can non-invasively differentiate patients newly diagnosed with MM from those with MGUS and should therefore be evaluated prospectively as a potential diagnostic marker.

Oncogene-induced senescence: a potential breakpoint mechanism against malignant transformation in plasma cell disorders.

Oncogene-induced senescence (OIS) is a cellular tumor-suppressive mechanism present in several premalignant conditions. Here, we analyze the possible impact of OIS on malignant transformation in plasma cell disorders. Tumor samples from 125 patients with different disease stages were analyzed immunohistochemically for expression of senescence markers. Protein expression of cyclin-dependent kinase inhibitor p21Cip1/Waf1 was significantly higher in smoldering multiple myeloma (SMM) compared to monoclonal gammopathy of undetermined significance (MGUS) (p = .02) or symptomatic multiple myeloma (MM) (p = .005). SMM plasma cells expressing p21Cip1/Waf1 were negative for Ki67, consistent with senescence. While p27Kip1 was highly expressed in healthy controls, MGUS and SMM, expression decreased significantly in MM (p = .02). SMM plasma cells displayed a mutually exclusive expression of p21Cip1/Waf1/p27Kip1 suggesting compensatory mechanisms of senescence. In conclusion, we found markers of cellular senescence differentially expressed in SMM compared to MGUS and MM supporting the hypothesis of OIS as a breakpoint mechanism against malignant transformation in plasma cell disorders.

Quantification of number of CD38 sites on bone marrow plasma cells in patients with light chain amyloidosis and smoldering multiple myeloma.

BACKGROUND: Recent approaches in multiple myeloma (MM) treatment have targeted CD38. As antigen expression levels on plasma cells (PCs) were demonstrated to affect response to monoclonal antibody (mAb) treatment, a precise characterization of PC phenotype is warranted. METHODS: Anti-CD38 mAb (isatuximab) was tested for antibody-dependent cellular cytotoxicity (ADCC) in MM cell lines. Quantification of the number of sites (NOS) of CD38 on bone marrow PCs and other immune cells obtained from light chain (AL) amyloidosis (n = 46) and smoldering multiple myeloma (SMM) patients (n = 19) was performed with two different quantitative flow cytometry (QFCM) applications. RESULTS: ADCC activity of isatuximab was observed in cell lines with >100 × 103 CD38-NOS only. The average PC CD38-NOS was 153 ± 53 × 103 in AL amyloidosis and 138.7 ± 53 × 103 in SMM patients. Eight (17%) AL amyloidosis and 4 (21%) SMM patients showed a PC CD38-NOS level <100 × 103 . In four AL amyloidosis and two SMM patients <10% of PCs had a CD38-NOS ≥100 × 103 . The CD38-NOS identified on bone marrow lymphocytes, monocytes, and granulocytes was two log units below the CD38-NOS on PCs (P < 0.001). No significant differences in CD38-NOS expression levels on any of the analyzed PC subpopulations in AL amyloidosis and SMM patients were identified. CONCLUSION: Levels of CD38 expression affect the isatuximab-mediated ADCC in vitro. As PCs of patients with AL amyloidosis and SMM do not homogenously express high CD38 our data provide a rationale for assessment of CD38-NOS in patients with PC disorders prior to anti-CD38 treatment. © 2018 International Clinical Cytometry Society.