DNA Flow Cytometry and Metaphase Cytogenetics Can Predict Progression of Asymptomatic Monoclonal Gammopathies (AMG) to Symptomatic Multiple Myeloma (MM).

Abstract Abstract 2915 Background: AMG is the most common plasma cell dyscrasia, currently classified as either monoclonal gammopathy of undetermined significance (MGUS) or asymptomatic multiple myeloma (AMM), based on the level of monoclonal immunoglobulin (M-protein), bone marrow plasmacytosis and other criteria defined by the International Myeloma Working Group. While information is available on the impact of clinical variables such as bone marrow plasmacytosis, free light chains, isotype and M-protein on the hazard of progression to symptomatic MM (MM), little is known about the value of the karyotype and DNA content, as determined by DNA/cIg flow cytometry, on the risk of progression from AMG to MM. Methods: Patients from the Myeloma Institute for Research and Therapy (MIRT) with AMG that were enrolled in a prospective observational clinical trial were evaluated. All patients underwent detailed clinical staging at entry and were followed at pre-specified intervals per protocol. Cox proportional hazards regression was used to model univariate and multivariate associations of baseline features with progression to MM. The number of distinct DNA stem lines in the flow cytometry assay, their percentages, respective DNA Indices (DI), cytoplasmic Immunoglobulin Indices (cIgI), and percent of cells in S phase were evaluated alone and in relation to the karyotype report at baseline. A DI between 0.99 and 1.01 referred to diploidy, lesser than 0.99 to hypodiploidy and more than 1.01 hyperdiploidy. Results: Data from 267 eligible MIRT patients with AMG were analyzed. Of these patients 99% (265/267) had performed DNA/cIg flow cytometry and had a karyotype report at diagnosis. Cytogenetic abnormalities were detected in 20 of the 265 patients from whom data were available. From the 265 patients from whom DNA/cIg flow cytometry data were available, no abnormal clones were identified in 14% (37/265), one clone was identified in 95 patients (36%), two clones in 122 patients (46%), three clones in 10 (4%), and in 1 patient 4 clones were identified. Most patients with abnormal DNA content had hyperdiploid clones (132/243 patients). The second most frequent finding was diploid DI, in 39% (104/243) of patients; 3% (7/243) had a hypodiploid DI. The median DI was 1.01 (0.9–2.02) and median cIg was 7 (1–50). Interestingly, the median cIgI value in AMG was more than twice that of its value (3.4, 1–22) in Total Therapy 3 MM patients (p=0.001). In univariate analysis of the parameters in this study, the presence of an abnormal karyotype (p=0.032, HR=2.62), the number of DNA/cIg clones (p=0.016, HR=1.69) and the percentage of the dominant clone (p=0.003, HR=1.03) were significantly related to progression to MM. Ploidy by DNA/cIg analysis, the S-phase fraction, and cIg did not reach statistical significance (p=0.863, p=0.132 and p=0.240, respectively). In multivariate analysis, only the number of abnormal clones (p=0.013, HR=1.78) retained statistical significance, while the percentage of the dominant clone neared significance (p=0.070, HR=1.02). Using running log rank tests we were able to identify optimal cut-points for the percentage of the dominant clone and the number of clones (12% and 2 clones respectively). From these, a risk score was obtained which identifies three distinct groups with 3-yr MM progression probabilities of 12%, 30% and 67% (p<0.001) (Figure 1). Conclusions: Abnormal metaphase cytogenetics and DNA/cIg flow cytometry have a prognostic value in the prediction of progression of AMG to MM. Hyperdiploidy is the dominant finding in AMG, however, its presence or absence does not predict progression. Clonal heterogeneity, as portrayed through DNA/cIg flow cytometry analysis, with the number of abnormal clones and the percentage of the dominant clone were major prognostic factors for progression to MM. Taken together they identify three distinct subgroups with a low (12%), moderate (30%) and high (67%) probability of 3-year time to progression to MM. Disclosures: Dhodapkar: Celgene: Research Funding; KHK: Research Funding.

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SWOG S0120 Observational Trial for MGUS and Asymptomatic Multiple Myeloma (AMM): Imaging Predictors of Progression for Patients Treated At UAMS,

Blood ◽

10.1182/blood.v118.21.3955.3955 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3955-3955

Author(s):

Christoph Heuck ◽

Rachael Sexton ◽

Madhav Dhodapkar ◽

Qing Zhang ◽

Saad Usmani ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Research Funding ◽

Cox Regression ◽

Time Dependent ◽

M Protein ◽

Risk Scores ◽

Imaging Studies ◽

Focal Lesions ◽

Pet Ct

Abstract Abstract 3955 Background: MGUS counts for the majority of monoclonal gammopathies and can be found in approximately 3% of adults older than 50 years. MGUS progresses to active Multiple Myeloma (MM) at a rate of 1–2% per year, thus imparting an average risk of 25% for progression (PRO) over a lifetime once diagnosed. Unfortunately no single laboratory, molecular or imaging variable can reliably predict PRO. S0120 accrued 363 patients at 69 sites across the US between January 1, 2004 and November 1, 2011, of whom 166 had MGUS and 190 AMM, defined according to IMWG criteria, on whom laboratory, gene expression and imaging studies were collected in a prospective fashion. Here we report the results of imaging studies as predictors of progression. Methods: 262 patients with evaluable follow-up were enrolled at the University of Arkansas for Medical Sciences (UAMS) site. MRI and PET-CT studies were performed at baseline and serially thereafter until PRO to symptomatic MM defined by standard variables of M-protein, bone marrow findings and CRAB criteria, according to protocol. Lab studies were performed at three months, six months and one year after registration, then every 12 months for a total of 5 years from registration as well as within 14 days of decision to discontinue observation or within 14 days of progression. MRI parameters included the number of focal lesions (FL) recognized by short TI inversion recovery (STIR) analysis of the axial bone marrow along with an account of bone marrow background intensity compared to adjacent muscles (hypo-, iso-, hyper-intense). PET-CT parameters included number of FDG-avid focal lesions (PET-FL), SUVmax of PET-FL, presence of extra-medullary disease (EMD) as well as the FDG avidity score at L5 (SUV-L5). Evaluable baseline MRI and PET studies were available for 235 and 224 patients, respectively. Results: In the 262 eligible patients enrolled and followed at UAMS, the two subgroups of MGUS and AMM differed by definition in M-protein and bone marrow plasmacytosis; in addition, IgA subclass and Hyperdiploidy molecular subgroup were overrepresented in the AMM group. Patients in the AMM group also had higher risk scores defined by the GEP 70-gene risk model (GEP70). At 24 months from study entry, 18.8% of all patients had progressed to MM (25.6% of AMM patients and 8.2% of MGUS patients) and 11.5% had begun MM therapy (15.8% of AMM patients and 4.5% of MGUS patients). Univariate Cox regression strongly indicated that age ≥ 65, serum albumin <3.5g/dL, B2M >+3.5mg/L, detection of any cytogenetic abnormalities (CA), and suppression of uninvolved light chains were adversely associated with time to PRO. The AMM-constituting features, bone marrow plasmacytosis >10%, M-protein >30g/L, and abnormal K/L ratio also conferred greater hazard of PRO. Risk scores > −0.26 and >1.5 for GEP70 and GEP80, respectively, as well as detection of focal lesions by MRI at baseline carried an elevated HR for PRO. A multivariate Cox regression showed only elevated M-protein, abnormal K/L ratio and GEP70 risk scores > =0.26 to be strongly associated with time to PRO. In the context of this MV model, disease subtype (AMM v MGUS) was insignificant. Inclusion of development of MRI-FL or and PET-FL as time-dependent variables showed that they were associated with time to PRO with HRs of 27.12 and 32.18 respectively. Abnormal K/L ratio and elevated M-protein were lost in this MV model. Analyzing variables linked to initiation of MM therapy, abnormal K/L ratio, elevated BM plasmacytosis, elevated M-protein, GEP70 risk scores >-0.26 as well as detection of MRI-FL at baseline (≥1 FL: HR=4.90; ≥3FL: HR=10.00) were univariately significant. On multivariate analysis, abnormal K/L ratio, elevated M-protein and GEP70 risk scores > – 0.26 were associated with time to treatment for MM. Inclusion of development of MRI-FL or PET-FL as a time dependent variable were associated with time to treatment with HRs of 29.12 and 36.50 respectively. Conclusion: To our knowledge, this is the first comprehensive effort that has used available imaging modalities along with established laboratory and pathology investigations in an attempt to distinguish features predictive of PRO from MGUS to active MM. In addition to the established “high-risk” MGUS/AMM features, we found that presence of MRI-FL at baseline, presence of CA and GEP70 scores >-0.26 carry a higher risk of PRO. Disclosures: Shaughnessy: Myeloma Health, Celgene, Genzyme, Novartis: Consultancy, Employment, Equity Ownership, Honoraria, Patents & Royalties. Barlogie:Celgene: Consultancy, Honoraria, Research Funding; IMF: Consultancy, Honoraria; MMRF: Consultancy; Millennium: Consultancy, Honoraria, Research Funding; Genzyme: Consultancy; Novartis: Research Funding; NCI: Research Funding; Johnson & Johnson: Research Funding; Centocor: Research Funding; Onyx: Research Funding; Icon: Research Funding.

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Minimal Residual Disease in Autografts and Bone Marrow of Patients with Multiple Myeloma: 8-Color Multiparameter Flow Cytometry (EuroFlow-NGF) Vs. Next-Generation Sequencing

Blood ◽

10.1182/blood-2020-137014 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 22-23

Author(s):

Hiroyuki Takamatsu ◽

Naoki Takezako ◽

Takeshi Yoroidaka ◽

Takeshi Yamashita ◽

Ryoichi Murata ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Research Funding ◽

Prognostic Value ◽

Residual Disease ◽

Multiparameter Flow Cytometry ◽

Next Generation ◽

Generation Sequencing ◽

Minimal Residual

Background: Autologous stem cell transplantation (ASCT) in conjunction with novel therapeutic drugs can dramatically improve response rates and the prognoses of patients with multiple myeloma (MM). However, most patients with MM ultimately relapse due to minimal residual disease (MRD). Next-generation multiparameter flow cytometry (MFC) (EuroFlow-NGF) and next-generation sequencing (NGS) are currently the standard methods to assess MRD. Aims: To compare the prognostic value of MRD detection in autografts and bone marrow (BM) cells using 8-color MFC (EuroFlow-NGF) and NGS (Adaptive Biotechnologies), and also MRD levels between fresh and cryopreserved autografts using NGF. Methods: The study enrolled 52 newly-diagnosed MM patients who underwent ASCT. The median age ASCT was 61 (range 41-69) years and included 29 males and 23 females at ISS I (n = 17), II (n = 23), and III (n = 12). Of these, 18 patients harbored high-risk chromosomal abnormalities including t(4;14) (n = 15), del17p and t(4;14) (n = 2), and complex (n = 1). Bortezomib-based chemotherapy was used for induction together with melphalan at 140 mg/m2 (n = 1) and 200 mg/m2 (n = 51) for conditioning before ASCT. 39 of 52 (75%) patients received maintenance therapy until progressive disease. The best responses achieved post-ASCT included 30 sCR, 4 CR, 15 VGPR, and 3 PR. Forty autografts, one from each MM patient, were analyzed using NGF and NGS protocols, and BM cells at pre/post-ASCT and autografts derived from 16 patients were analyzed using NGS. The EuroFlow-NGF method uses standard sample preparation; large numbers of cells are evaluated using an optimized 8-color antibody panel that facilitates accurate identification of discrimination between phenotypically aberrant plasma cells (aPCs) and their normal counterparts (Flores-Montero et al., Leukemia 2017). NGS-based MRD assessment was performed using Adaptive's standardized NGS-MRD Assay (Seattle, WA) (Martinez-Lopez et al., Blood 2014). Eight additional autografts were used to assess MRD in both fresh and cryopreserved samples by NGF. Results: MRD was evaluated in 48 of 52 autografts (92%) using NGF and in 44 of 52 autografts (85%) using NGS. We identified aPCs in autografts based on multivariate analysis of individual cell populations (e.g., CD56+, CD19−, CyIgκ+, and CD117+). As the results of NGF revealed a strong correlation with respect to MRD in fresh vs. thawed autografts (r = 0.999, P < 0.0001), MRD was subsequently evaluated in thawed autografts. The sensitivity of NGF was 1 × 10−5-2 × 10−6; the sensitivity of NGS was 1 × 10−6. 28 of 48 (58%) of the autografts were MRD-positive by NGF; 30 of 44 (68%) of the autografts were MRD-positive by NGS. MRD levels in autografts using NGF and NGS correlated with one another (r = 0.69, P < 0.0001; Fig. 1A). MRD negative in autografts by NGF cases (MRDNGF (-)) and MRDNGS (-) tended to show better progression-free survival (PFS) than MRDNGF (+) (P = 0.195) and MRDNGS (+) (P = 0.156), respectively. Furthermore, MRDNGS (-) showed significantly better overall survival (OS) than MRDNGS (+) (P = 0.03) (Fig. 1C) while MRDNGF (-) showed better OS than MRDNGF (+) (P = 0.09) (Fig. 1B). Our data revealed only a minimal correlation between MRD in the autografts (median 1.1 × 10−5,range 0-7.29 × 10−4) and in the BM cells at pre-ASCT (median 5.05 × 10−3,range 6 × 10−6-2.64 × 10−1; r = 0.09, P = 0.7) or at post-ASCT (median 2.11 × 10−4,range 0-9.09 × 10−3; r = 0.14, P = 0.6); MRD detected in the autografts was > 27 times lower than that detected in pre-ASCT BM cells, and MRD detected in the post-ASCT BM cells was > 3 times lower than that detected in pre-ASCT BM cells except for one case in which the ratio was increased by two times. Interestingly, while MRD was detected in all BM cells at pre-ASCT (n = 16), 4 of 16 (25%) of these autografts were MRDNGS-negative. The median of MRD levels of the 4 cases in pre-ASCT and post-ASCT BM cells were 4.14 × 10−4 (range 6-583 × 10−6)and 1.8 × 10−5 (range 0-27 × 10−6), respectively. Conclusion: Although EuroFlow-NGF is a rapid and accurate method for detecting MRD, NGS was more sensitive and provided greater prognostic value than EuroFlow-NGF. Disclosures Takamatsu: Adaptive Biotechnologies: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Janssen Pharmaceutical: Consultancy, Honoraria, Research Funding; Ono pharmaceutical: Honoraria, Research Funding; SRL: Consultancy, Research Funding. Takezako:Bristol-Myers Squibb: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Janssen: Research Funding; Abbvie: Research Funding. Nakao:Symbio: Consultancy; Kyowa Kirin: Honoraria; Alexion: Research Funding; Novartis: Honoraria.

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Immunophenotypic Response After Allografting In Multiple Myeloma

Blood ◽

10.1182/blood.v122.21.3371.3371 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3371-3371 ◽

Cited By ~ 1

Author(s):

Luisa Giaccone ◽

Lucia Brunello ◽

Roberto Passera ◽

Moreno Festuccia ◽

Milena Gilestro ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Conflicts Of Interest ◽

Univariate Analysis ◽

Conditioning Regimen ◽

First Line ◽

Significant Difference ◽

The Impact

Abstract Background Minimal residual disease (MRD) by multiparameter flow-cytometry recently showed a promising role in predicting outcomes in patients with multiple myeloma. However, data on immunophenotypic response (IR) after allografting are lacking. Aim To evaluate the impact of IR and compare it to conventional complete remission (CR) following allografting in myeloma patients. Methods Sixty-six consecutive patients, median age 54 years (35-66), who underwent an allograft between January 2000 and December 2011 with a follow-up of at least 3 months were included. Disease response was evaluated by serum and urine electrophoresis, and bone marrow aspirate at baseline, 3, 6, 12, 18, 24 months after transplant and yearly thereafter. Skeletal survey or MRI were performed yearly or as clinically indicated (overt relapse or complaints of bone pain). Bone marrow aspirates had to contain at least 13000 cells/µL for flow-cytometry studies and IR was defined as absence of monoclonal plasma-cells detected by 4 or 6-colour staining with the following antibodies: CD38, CD138, CD56, CD19, CD45, cyKappa, cyLambda. CR was defined according to standard criteria (Durie et al, Leukemia 2006; 20:1467-73). Results Conditioning regimen was non-myeloablative 2Gy TBI-based in 55 patients, reduced intensity (fludarabine-melphalan-based) in 10 and myeloablative in 1 patient. Post-grafting immunosuppression consisted of cyclosporine with mycophenolate mofetil or methotrexate. Donors were HLA identical siblings in 58 patients and unrelated in 8. Only 1 patient received bone marrow as source of stem cells. Thirty-five/66 (53%) received the allograft as part of the first line treatment, whereas the remaining 31/66, (47%) were transplanted at relapse. At the time of transplant, 5/66 were both in IR and CR, 16 were only in IR and 4 patients were only in clinical CR. All 21 patients in IR at the time of transplant maintained it, while 26/45 (58%) entered IR after the allograft. Among patients surviving at least 3 months, overall treatment related mortality was 10.6% at 3 years. After a median follow-up of 69 months (range 19-147), the incidence of acute and chronic graft-versus-host disease was 45.6% and 49.3% without significant difference between responsive and non-responsive patients. At follow-up, overall, 24 patients achieved CR and IR (CR/IR group), 21 achieved IR but not CR because of persistence of urine/serum M-component (noCR/IR group), and 21 did not achieve either CR or IR (noCR/noIR group). Interestingly, none achieved CR without IR. Median overall survival (OS) and event-free survival (EFS) in patients who achieved IR were 96 and 55 months versus 36 and 7 months in those who did not (p<0.001). Median OS and EFS were not reached and 59 months in the CR/IR group, 77 and 15 months in the noCR/IR, and 30 and 5 months in the noCR/noIR respectively (p<0.001 for both EFS and OS-fig.1). In univariate analysis, being in the CR/IR group was the only significant predictor for prolonged OS and EFS (p<0.001). Of note, cumulative incidence of extra-medullary disease at first relapse after the allograft was 4% in the CR/IR, 32% in the noCR/IR and 15% in the noCR/noIR groups respectively (p<0.001). Receiving the allograft as first line therapy or later during the disease course did not significantly impact on OS and EFS. Conclusion The achievement of IR confers a favorable impact on OS and EFS after allografting. A higher incidence of extra-medullary in the noCR/IR group (some 30% of our patient cohort) may suggest that myeloma cells escape immune control outside the bone marrow. In this group, imaging studies such as positron emission tomography may clinically be indicated during follow-up to detect early relapse. Disclosures: No relevant conflicts of interest to declare.

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Role of Selectins in the Pathogenesis of Multiple Myeloma.

Blood ◽

10.1182/blood.v114.22.951.951 ◽

2009 ◽

Vol 114 (22) ◽

pp. 951-951 ◽

Cited By ~ 1

Author(s):

Abdel Kareem Azab ◽

Phong Quang ◽

Feda Azab ◽

Costas M Pitsillides ◽

John T Patton ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Endothelial Cells ◽

Cell Adhesion ◽

Board Of Directors ◽

Research Funding ◽

Plasma Cells ◽

Advisory Committees

Abstract Abstract 951 INTRODUCTION: Multiple Myeloma (MM) is characterized by widespread disease at diagnosis with the presence of multiple lytic lesions and disseminated involvement of the bone marrow (BM), implying that the progression of MM involves a continuous re-circulation of the MM cells in the peripheral blood and re-entrance into the BM. Selectins are adhesion molecules expressed by activated endothelium of venules and leukocytes, and are involved in the primary interaction of lymphocytes with the endothelium of blood vessels. The binding of selectins serves as a biologic brake, making leukocyte quickly decelerate by rolling on endothelial cells, as the first step of extravasation. In this study, we have investigated the role of selectins and their ligands in the regulation of homing of MM Cells to the BM and the therapeutic implications of this role. METHODS AND RESULTS: We have used flow cytometry to characterize the expression of E, L and P-selectins and their ligands on MM cell lines, patient samples and on plasma cells from normal subjects. We found that all MM cell lines and patient samples showed high expression of L and P, but little of no E-selectin. While normal plasma cells showed low expression of all selectins and ligands.(give numbers) A pan-selectin inhibitor GMI-1070 (GlycoMimetics Inc., Gaithersburg, MD) inhibited the interaction of recombinant selectins with the selectin-ligands on the MM cells in a dose response manner. We have tested the role of the selectins and their ligands on the adhesion of MM cells to endothelial cells and found that MM cells adhered preferentially to endothelial cells expressing P-selectin compared to control endothelial cells and endothelial cells expressing E-selectin (p<0.05). Moreover, we found that blockade of P-selectin on endothelial cells reduced their interaction with MM cells (p<0.01), while blockade of E and L-selectin did not show any effect. Treating endothelial cells with GMI-1070 mimicked the effect of blocking P-selectin. Moreover, we found that treating endothelial cells with the chemokine stroma cell-derived factor-1-alpha (SDF1) increased their expression of P but not E or L-selectin detected by flow cytometry. Neither the blockade of each of the selectins and their ligands nor the GMI-1070 inhibited the trans-well chemotaxis of MM cells towards SDF1-alpha. However, blockade of P-selectin (p<0.001) on endothelial cells by GMI-1070 inhibited the trans-endothelial chemotaxis of MM cells towards SDF1-alpha. Both adhesion to endothelial cells and activation with recombinant P-selectin induced phosphorylation of cell adhesion related molecules including FAK, SRC, Cadherins, Cofilin, AKT and GSK3. GMI-1070 decreased the activation of cell adhesion molecules induced by both recombinant P-selectin and endothelial cells. Using in vivo flow cytometry we found that both anti P-selectin antibody and GMI-1070 prevented the extravasation of MM cells out of blood vessels into the bone marrow in mice. Moreover, we found that, in a co-culture system, endothelial cells protected MM cells from bortezomib induced apoptosis, an effect which was reversed by using GMI-1070, showing synergistic effect with bortezomib. CONCLUSION: In summary, we showed that P-selectin ligand is highly expressed in MM cells compared to normal plasma cells, and that it plays a major role in homing of MM cells to the BM, an effect which was inhibited by the pan-selectin inhibitor GMI-1070. This provides a basis for testing the effect of selectin inhibition on tumor initiation and tumor response to therapeutic agents such as bortezomib. Moreover, it provides a basis for future clinical trials for prevention of MM metastasis and increasing efficacy of existing therapies by using selectin inhibitors for the treatment of myeloma. Disclosures: Patton: GlycoMimetics, Inc: Employment. Smith:GlycoMimetics, Inc: Employment. Sarkar:GlycoMimetics, Inc: Employment. Anderson:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Magnani:GlycoMimetics, Inc.: Employment. Ghobrial:Millennium: Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau.

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The Prognostic Significance of Polyclonal Bone Marrow Plasma Cells in Patients with Actively Relapsing Multiple Myeloma

Blood ◽

10.1182/blood.v128.22.1194.1194 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1194-1194

Author(s):

Toshi Ghosh ◽

Wilson I Gonsalves ◽

Dragan Jevremovic ◽

S. Vincent Rajkumar ◽

Michael M. Timm ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

High Risk ◽

Research Funding ◽

Plasma Cells ◽

Labeling Index ◽

Light Chains ◽

Fish Cytogenetics ◽

Kaplan Meier

Abstract Background: Prior studies suggest that the presence of >5% polyclonal plasma cells (pPCs) among total plasma cells (PCs) within the bone marrow (BM) is associated with a longer progression-free survival, higher response rates, and lower frequency of high-risk cytogenetic abnormalities in patients with newly diagnosed multiple myeloma (MM). However, the incidence and prognostic utility of this factor in patients with relapsed and/or refractory MM has not been previously evaluated. Thus, we evaluated the prognostic value of quantifying the percentage of pPCs among the total PCs in the BM of patients with actively relapsing MM. Methods: We evaluated all MM patients with actively relapsing disease (biochemical and/or symptomatic) seen at the Mayo Clinic, Rochester, from 2012 to 2013, who had BM samples evaluated by seven-color multiparametric flow cytometry. All patients had at least 24 months of follow-up from the date of flow evaluation. Cell surface antigens were assessed by direct immunofluorescence antibodies for CD45, CD19, CD38, CD138, cytoplasmic Kappa and Lambda Ig light chains, and DAPI nuclear stain. The flow cytometry data was collected using the Becton Dickinson FACSCanto II instruments that analyzed 150,000 events (cells); this data was then analyzed by multi-parameter analysis using the BD FACS DIVA Software. PCs were selectively analyzed through combinatorial gating using light scatter properties and CD38, CD138, CD19, and CD45. Clonal PCs were separated from pPCs based on the differential expression of CD45, CD19, DAPI (in non-diploid cases), and immunoglobulin light chains. The percentage of pPCs was calculated in total PCs detected. Survival analysis was performed by the Kaplan-Meier method and differences were assessed using the log rank test. Results: There were 180 consecutive patients with actively relapsing MM who had BM biopsies analyzed via flow cytometry as part of their routine clinical evaluation. The median age of this group was 65 years (range: 40 - 87); 52% were male. At the time of this analysis, 104 patients had died, and the 2-year overall survival (OS) rate for the cohort was 58%. The median number of therapies received was 4 (range: 1 - 15). Of these patients, 61% received a prior ASCT, and almost all (99%) received prior regimens containing either immunomodulators or proteasome inhibitors. There were 55 (30%) patients with >5% pPCs among the total PCs in their BM. The median percentage of pPCs among total PCs in these 55 patients was 33% (range: 5 - 99). The median OS for those with >5% pPCs was not reached compared with 22 months for those with <5% pPCs (P = 0.028; Figure 1). Patients with <5% pPCs PCs had a higher likelihood of high-risk FISH cytogenetics compared with the rest of the patients. In a univariate analysis, increasing number of pPCs was associated with an improved OS, while higher labeling index, number of prior therapies, and the presence of high-risk FISH cytogenetics were associated with a worse OS. In a multivariate analysis, only the increasing number of pPCs (P = 0.006), higher labeling index (P = 0.0002) and number of prior therapies (P = 0.003) retained statistical significance. Conclusion: Quantitative estimation of the percentage of pPCs among the total PCs in the BM of patients with actively relapsing MM was determined to be a predictor of worse OS. As such, this parameter is able to identify a group of patients with MM with actively relapsing disease who have a particularly poor outcome. Further studies evaluating its biological significance are warranted. Figure 1 Kaplan-Meier curve comparing OS between patients with ≥5% pPCs and <5% pPCs among the total PCs in their BM. Figure 1. Kaplan-Meier curve comparing OS between patients with ≥5% pPCs and <5% pPCs among the total PCs in their BM. Disclosures Kapoor: Celgene: Research Funding; Amgen: Research Funding; Takeda: Research Funding. Gertz:Prothena Therapeutics: Research Funding; Novartis: Research Funding; Alnylam Pharmaceuticals: Research Funding; Research to Practice: Honoraria, Speakers Bureau; Med Learning Group: Honoraria, Speakers Bureau; Celgene: Honoraria; NCI Frederick: Honoraria; Sandoz Inc: Honoraria; GSK: Honoraria; Ionis: Research Funding; Annexon Biosciences: Research Funding. Kumar:AbbVie: Research Funding; Noxxon Pharma: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Onyx: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Research Funding; Kesios: Consultancy; Glycomimetics: Consultancy; BMS: Consultancy.

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Prevalence of Smoldering Multiple Myeloma: Results from the Iceland Screens, Treats, or Prevents Multiple Myeloma (iStopMM) Study

Blood ◽

10.1182/blood-2021-148617 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 151-151

Author(s):

Sigrun Thorsteinsdottir ◽

Gauti Kjartan Gislason ◽

Thor Aspelund ◽

Sæmundur Rögnvaldsson ◽

Jon Thorir Thorir Oskarsson ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

High Risk ◽

Risk Stratification ◽

Light Chain ◽

Research Funding ◽

Plasma Cells ◽

Population Based ◽

M Protein ◽

Screening Study

Abstract Background Smoldering multiple myeloma (SMM) is an asymptomatic precursor condition to multiple myeloma (MM). Emerging data from clinical trials indicate that - compared to watchful monitoring - initiation of therapy at the SMM stage might be indicated. Currently, there is no established screening for SMM in the general population and therefore patients are identified incidentally. Here, we define for the first time, epidemiological and clinical characteristics of SMM in the general population based on a large (N>75,000) population-based screening study. Methods The iStopMM study (Iceland Screens Treats or Prevents Multiple Myeloma) is a nationwide screening study for MM precursors where all residents in Iceland over 40 years of age and older were invited to participate. Participants with a positive M-protein on serum protein electrophoresis (SPEP) or an abnormal free light chain (FLC) analysis entered a randomized controlled trial with three arms. Participants in arm 1 continued care in the Icelandic healthcare system as though they had never been screened. Arms 2 and 3 were evaluated at the study clinic with arm 2 receiving care according to current guidelines. In arm 3 bone marrow testing and whole-body low-dose CT (WBLDCT) was offered to all participants. SMM was defined as 10-60% bone marrow plasma cells on smear or trephine biopsy and/or M-protein in serum ≥3 g/dL, in the absence of myeloma defining events. Participants in arm 3 were used to estimate the prevalence of SMM as bone marrow biopsy was performed in all participants of that arm when possible. The age- and sex-specific prevalence was determined with a fitted function of age and sex, and interaction between those. Diagnosis at baseline evaluation of the individuals in the study was used to define the point prevalence of SMM. Results Of the 148,704 individuals over 40 years of age in Iceland, 75,422 (51%) were screened for M-protein and abnormal free light chain ratio. The 3,725 with abnormal screening were randomized to one of the three arms, and bone marrow sampling was performed in 1,503 individuals. A total of 180 patients were diagnosed with SMM, of which 109 (61%) were male and the median age was 70 years (range 44-92). Of those, a total of 157 (87%) patients had a detectable M-protein at the time of SMM diagnosis with a mean M-protein of 0.66 g/dL (range 0.01-3.5). The most common isotype was IgG in 101 (56%) of the patients, 44 (24%) had IgA, 2 (1%) had IgM, and 5 (3%) had biclonal M-proteins. A total of 24 (13%) patients had light-chain SMM. Four patients (2%) had a negative SPEP and normal FLC analysis at the time of SMM diagnosis despite abnormal results at screening. A total of 131 (73%) patients had 11-20% bone marrow plasma cells at SMM diagnosis, 32 (18%) had 21-30%, 9 (5%) had 31-40%, and 8 (4%) had 41-50%. Bone disease was excluded with imaging in 167 (93%) patients (MRI in 25 patients, WBLDCT in 113 patients, skeletal survey in 27 patients, FDG-PET/CT in 1 patient), 13 patients did not have bone imaging performed because of patient refusal, comorbidities, or death. According to the proposed 2/20/20 risk stratification model for SMM, 116 (64%) patients were low-risk, 47 (26%) intermediate-risk, and 17 (10%) high-risk. A total of 44 (24%) had immunoparesis at diagnosis. Using the PETHEMA SMM risk criteria on the 73 patients who underwent testing with flow cytometry of the bone marrow aspirates; 39 (53%) patients were low-risk, 21 (29%) patients were intermediate-risk, and 13 (18%) patients were high-risk. Out of the 1,279 patients randomized to arm 3, bone marrow sampling was performed in 970, and 105 were diagnosed with SMM (10.8%). The prevalence of SMM in the total population was estimated to be 0.53% (95% CI: 0.49-0.57%) in individuals 40 years of age or older. In men and women, the prevalence of SMM was 0.70% (95% CI: 0.64-0.75%) and 0.37% (95% CI: 0.32-0.41%), respectively, and it increased with age in both sexes (Figure). Summary and Conclusions Based on a large (N>75,000) population-based screening study we show, for the first time, that the prevalence of SMM is 0.5% in persons 40 years or older. According to current risk stratification models, approximately one third of patients have an intermediate or high risk of progression to MM. The high prevalence of SMM has implications for future treatment policies in MM as treatment initiation at the SMM stage is likely to be included in guidelines soon and underlines the necessity for accurate risk stratification in SMM. Figure 1 Figure 1. Disclosures Kampanis: The Binding Site: Current Employment. Hultcrantz: Daiichi Sankyo: Research Funding; Amgen: Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees, Research Funding; Curio Science LLC: Consultancy; Intellisphere LLC: Consultancy. Durie: Amgen: Other: fees from non-CME/CE services ; Amgen, Celgene/Bristol-Myers Squibb, Janssen, and Takeda: Consultancy. Harding: The Binding Site: Current Employment, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Landgren: Janssen: Research Funding; Janssen: Other: IDMC; Celgene: Research Funding; Takeda: Other: IDMC; Janssen: Honoraria; Amgen: Honoraria; Amgen: Research Funding; GSK: Honoraria. Kristinsson: Amgen: Research Funding; Celgene: Research Funding.

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Development of an Easily Accessible Patient-Derived Xenograft (PDX) Mouse Model in Multiple Myeloma

Blood ◽

10.1182/blood-2019-121933 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5538-5538

Author(s):

Can Li ◽

Yogesh Jethava ◽

Ivana Frech ◽

Fenghuang Zhan

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Mouse Model ◽

Mouse Models ◽

Mononuclear Cells ◽

Plasma Cells ◽

M Protein ◽

Nsg Mice ◽

Patient Derived Xenograft

Preclinical mouse models are important tools to recapitulate human multiple myeloma (MM) disease. Different preclinical models allow for specific hypothesis-driven research and enables researchers to address multiple questions. Though the SCID-Hu and SCID-synth-hu mice, and a recently established humanized mouse model containing the knock-in of human cytokine genes permit the growth of primary pre-neoplastic and malignant plasma cells, the high-cost, long-term workflow, lack of access to genetically engineered mice are overwhelming disadvantages of these current humanized MM mouse models. Our objective is to establish a unique patient-derived-xenograft (PDX) MM mouse model as an easily accessible approach for prevention and therapy of human MM disease. Bone marrow aspirates from MM patients upon diagnosis were obtained from the Multiple Myeloma Molecular Epidemiology Resource (University of Iowa) and mononuclear cells were isolated. Groups of 7-8 weeks old NOD/SCID/IL2RΥgnull (NSG) mice were administrated with sub-lethal irradiation. 3-5×106 unsorted MM patient-derived bone marrow mononuclear cells were intravenously injected into each recipient NSG mouse after irradiation. In order to monitor engraftment, recipient mice were bled weekly from week 2 after inoculation and serial Serum Protein Electrophoresis (SPEP) tests of recipient mice were performed. Detection of distinct M-protein band by the SPEP test with weight loss and/or limited mobility of injected recipient mice were indicative of successful MM engraftment and the endpoint of this study. M protein was found in all 30 mice after 3 ~ 5 weeks of injection human MM mononuclear cells. To further confirm that the M protein was secreted from human MM cells, we performed flow cytometry to determine human MM cells using anti-human CD138 antibody from mouse tissues. About 10% human CD138+ MM cells were detected in spleen and bone marrow from these PDX-NSG mice by flow cytometry, whereas human CD138+ cells were absent in irradiated control mice without injection of human MM cells. We also performed immunohistochemistry on bone marrow sections of PDX-NSG mice. Human CD138 protein and human light chain protein were positively stained on these samples. We next examined MM related organ damage, which is part of the defining criteria of human MM disease. Elevated blood urea nitrogen (BUN) was detected in xenograft mouse serum compared to control mice, suggesting renal insufficiency rendered by MM engraftment. Meanwhile, xenograft mouse kidney sections were stained with PAS (Periodic acid-Schiff), which demonstrated protein and cellular cast nephropathy and inflammatory infiltration. We also performed TRAP staining on representative xenograft mouse bone sections. TRAP positive osteoclasts were increased in the distal portions of the femur bones derived from these PDX-NSG mice. We present robust data that a newly developed PDX-NSG model can grow primary human MM cells. Our hypothesis holds that cells from the same patient bone marrow microenvironment support tumor plasma cells survival and growth. These factors enables this new model to recapitulate more accurately the features of human MM. We will further investigate whether this new humanized PDX-NSG model provides a better tool for understanding MM development and for a personalized medicine. Disclosures Zhan: BIPHARM LLC: Consultancy, Other: % Allocation of Profit.

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Measurable Residual Disease in Extracellular Vesicles from Bone Marrow and Peripheral Blood of Patients with Multiple Myeloma: A Proof-of-Concept Study

Blood ◽

10.1182/blood-2021-149398 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 4712-4712

Author(s):

Rui Bergantim ◽

Mélanie A.G. Barbosa ◽

Sara Peixoto da Silva ◽

Bárbara Polónia ◽

Hugo R. Caires ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Complete Remission ◽

Research Funding ◽

Residual Disease ◽

Disease Diagnosis ◽

Invasive Monitoring ◽

Protein Markers ◽

Measurable Residual Disease

Abstract BACKGROUND: Multiple myeloma (MM) treatment improved substantially in the last years, with unprecedented survival outcomes. However, even when achieving complete remission, patients ultimately relapse. Therefore, monitoring measurable residual disease (MRD) is crucial to assess treatment response and define the depth of patients' remission status. However, this currently still requires invasive bone marrow (BM) aspirates, which severely hinders real-time monitoring of the disease. Therefore, the identification of biomarkers of MRD in the peripheral blood (PB) of patients would allow a more frequent and minimally invasive monitoring of MRD. Extracellular Vesicles (EVs) are small particles (30-1000nm) shed by all cells, which are found in all biofluids including the BM and PB. These particles carry a specific cargo from their cell of origin, including proteins, enclosed by a lipidic layer. Therefore, they have been described as a possible source of cancer biomarkers, with potential to monitor MRD. AIMS: This study aimed to implement a protocol for the isolation of EVs from the BM and PB of MM patients at distinct stages of the disease (diagnosis and remission), in order to detect and compare the levels of known MRD biomarkers in their cargo. METHODS: The study was previously approved by the Ethical Committee of CHSJ and patient's consent was obtained. EVs from BM and PB Platelet-Poor Plasma (PPP) were isolated by size-exclusion chromatography (SEC), and further concentrated by ultrafiltration (UF). Then, the EVs were characterized according to their size and concentration (by Nanoparticle Tracking Analysis), morphology (by Transmission Electron Microscopy), protein concentration (Lowry protein assay) and presence of EV-associated protein markers (Western Blot - WB). In addition, 16 known MRD and MM biomarkers were analyzed by WB in the isolated EVs from PB and BM of seven patients, at two main stages of the disease - diagnosis versus response after autologous stem cell transplant (ASCT). Clinical features regarding cytogenetics and immunophenotypic markers using multi-parameter flow cytometry (MFC) were analyzed and compared. RESULTS: The two-step protocol described allowed the isolation of size-resolved EVs from both PB and BM of MM patients. The EVs isolated (both from PB and BM) presented a size-range from 50 to 500nm and presented EV-associated protein markers, such as CD81 and CD63. Moreover, several MM MRD biomarkers (e.g. CD56, CD45, CD38 and light chain) were detected in the cargo of the EVs from BM and PB at diagnosis and complete remission. The biomarkers of MM and MRD detected in the cargo of PB EVs were mainly the same as the ones detected in the cargo of BM EVs. The complete remission after ASCT was mostly associated with a decrease in the expression of EV-associated MM markers in both the BM and the PB; however, in some patients a few of the markers persisted at this stage when compared to diagnosis. In fact, the expression of CD45 and HLA-DR persisted at the remission stage in 3 and 2, respectively, out of 5 patients presenting these markers at diagnosis. Moreover, an increased expression of CD56 was also detected at remission in 3 out of 7 patients. By correlating these data with patient's routine work-up it was found that patients with persistent CD45 didn't reach 10^-5 MRD negative by flow cytometry. CONCLUSIONS: Taken together, this work suggests that it is possible to detect MM markers in EVs from either BM or PB of MM patients and compare their expression at different stages of the disease (diagnosis and remission after ASCT). Importantly, our results demonstrate the importance and potential of analyzing EVs cargo from PB, suggesting the possibility of using them for minimally invasive monitoring of MRD in MM patients. ACKNOWLEDGEMENTS: The authors acknowledge Celgene/BMS for providing funding to this work (Project Looker - Grant_138800). The authors acknowledge Cytogenetics Laboratory, Department of Clinical Hematology, Centro Hospitalar e Universitário São João and Flow Cytometry Laboratory, Department of Clinical Pathology, Centro Hospitalar e Universitário São João. Disclosures Bergantim: Amgen: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; BMS: Consultancy, Research Funding, Speakers Bureau; Takeda: Consultancy, Speakers Bureau. Barbosa: BMS: Research Funding. Silva: BMS: Research Funding. Polónia: BMS: Research Funding. Caires: BMS: Research Funding. Guimarães: BMS: Research Funding; Amgen: Research Funding. Vasconcelos: BMS: Research Funding; Amgen: Research Funding.

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The Role of 18f-FDG-PET/CT in Characterizing Depth of Response in High Risk Smoldering Multiple Myeloma Patients Treated with Carfilzomib, Lenalidomide, and Dexamethasone (KRd)

Blood ◽

10.1182/blood-2020-136182 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 11-12

Author(s):

Elizabeth Hill ◽

Neha Korde ◽

Candis Morrison ◽

Alexander Dew ◽

Ashley Carpenter ◽

...

Keyword(s):

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Clinical Trials ◽

Maintenance Therapy ◽

Research Funding ◽

Data Monitoring ◽

Independent Data ◽

Genetics Research ◽

Pet Ct

Introduction A direct association exists between minimal residual disease (MRD) negativity and prolonged survival in multiple myeloma (MM) (Landgren et al, BMT 2016). 18F-fluoro-deoxy-glucose (FDG) positron emission tomography-computed tomography (PET/CT) is a recommended monitoring technique for patients with MM as persistence of FDG uptake after induction therapy, prior to maintenance, is an independent risk factor for progression. Therefore PET/CT and MRD detection in the bone marrow are complementary prognostic tools prior to initiation of maintenance therapy. In patients with smoldering multiple myeloma (SMM), the presence of a focal FDG-avid lesion without underlying osteolytic lesion on PET/CT is associated with rapid progression to MM. However, little is known about the prognostic value of PET/CT for SMM patients receiving treatment. Herein, we show that treatment of high risk (HR)-SMM with carfilzomib, lenalidomide, and dexamethasone with lenalidomide maintenance (KRd-R) leads to sustained remissions detected on PET/CT imaging. Methods Trial design including key results for KRd-R in HR-SMM (NCT01572480) has been submitted to the meeting separately (abstract ID: 136148). As part of the study design, all eligible patients had bone marrow biopsies with multicolor flow cytometry (MRD sensitivity, 10-5) and whole-body PET/CT performed at baseline and at key time points, including achievement of complete response (CR) or completion of KRd induction (8 cycles), after 1 and 2 years of -R maintenance, and annually thereafter. PET/CTs were evaluated by nuclear medicine radiologists blinded to flow cytometry and considered positive if at least one focal hypermetabolic (above background reference) lesion and/or heterogenous bone marrow involvement were present, as defined by the IMWG (Hillengass et al. Lancet Oncol 2019). Results As of data cutoff, 46 patients had completed at least 8 cycles of therapy and had 2 sequential PET/CTs performed. By the end of induction therapy, no patient developed progressive disease and the overall response rate was 100%. Approximately 72% of patients with baseline negative PET/CTs remained negative, 11% of patients had resolution of previous focal/heterogenous FDG avidity, 15% of patients had decrease or stable focal/ heterogenous lesions, and 2% developed new focal lesions. Table 1 shows the results at subsequent time points of one and two years of maintenance therapy. Throughout this time period, one patient developed a lytic lesion after 1 year of maintenance therapy. However, 3 patients had either resolution or decrease in focal/heterogenous lesions. Specifically, after 8 cycles of combination therapy, 33 patients (70.2%, 95% CI 55.9 - 81.4%) had a response of MRD negative CR based on bone marrow flow cytometry and 26 patients (55.3%; 95% CI 41.2-68.6%) had a negative PET/CT in addition to MRD negative CR (Table 2). Conclusions It is important to evaluate the tools used in MM response assessment specifically in the SMM population as more studies report results of treatment in this population. MRD information can be used as a biomarker to evaluate the efficacy of different treatment strategies. This study demonstrates an exceptionally high rate of concordance between MRD negativity by flow cytometry and negative PET/CT after 8 cycles of KRd. However, 15% of patients were MRD negative yet had positive findings on PET/CT. While these lesions were not biopsy proven, some resolved during maintenance therapy. Further follow-up is needed to determine whether early MRD negativity in bone marrow with negative PET/CT correlates to longer overall survival and decreased progression to MM compared to those patients with a positive PET/CT. The use of PET/CT imaging may increase our understanding in assessing depth response to treatment in HR-SMM patients and be an important outcome predictor. Disclosures Korde: Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Landgren:Adaptive: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Takeda: Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Glenmark: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Research Funding; Janssen: Consultancy, Honoraria, Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Karyopharma: Research Funding; Binding Site: Consultancy, Honoraria; Takeda: Other: Independent Data Monitoring Committees for clinical trials, Research Funding; BMS: Consultancy, Honoraria; Cellectis: Consultancy, Honoraria; Glenmark: Consultancy, Honoraria, Research Funding; Juno: Consultancy, Honoraria; Seattle Genetics: Research Funding; Pfizer: Consultancy, Honoraria; Merck: Other; Karyopharma: Research Funding; Binding Site: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Cellectis: Consultancy, Honoraria; Juno: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Merck: Other.

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Molecular Characterization of Bone Marrow and Peripheral Blood Compartments from Patients with Plasma Cell Leukemia in the Mmrf Commpass Study

Blood ◽

10.1182/blood-2019-130697 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1782-1782

Author(s):

Sheri Skerget ◽

Austin Christofferson ◽

Sara Nasser ◽

Christophe Legendre ◽

The MMRF CoMMpass Network ◽

...

Keyword(s):

Cell Cycle ◽

Multiple Myeloma ◽

Bone Marrow ◽

Flow Cytometry ◽

Plasma Cell ◽

Peripheral Blood ◽

Research Funding ◽

Plasma Cells ◽

Cell Cycle Control ◽

Cell Leukemia

Plasma cell leukemia (PCL) is rare but represents an aggressive, advanced form of multiple myeloma (MM) where neoplastic plasma cells (PCs) escape the bone marrow (BM) and circulate in the peripheral blood (PB). Traditionally, PCL is defined by the presence of >20% circulating plasma cells (CPCs), however, recent studies have suggested that PCL be redefined as the presence of >5% CPCs. The Multiple Myeloma Research Foundation CoMMpass study (NCT01454297) is a longitudinal, observational clinical study with 1143 newly diagnosed MM patients. BM-derived MM samples were characterized using whole genome (WGS), exome (WES), and RNA (RNAseq) sequencing at diagnosis and each progression event. When >5% CPCs were detected by flow cytometry, PCs were enriched independently from both compartments, and T-cells were selected from the PB as a control for WGS and WES. This substudy within CoMMpass provides the largest, most comprehensively characterized dataset of matched MM and PCL samples to date, which can be leveraged to better understand the molecular drivers of PCL. At diagnosis, 813/1143 CoMMpass patients had flow cytometry data reporting the percent PCs in PB, of which 790 had <5%, 17 had 5-20%, and 6 had >20% CPCs. Survival analyses revealed that patients with 5-20% CPCs (median = 20 months) had poor overall survival (OS) outcomes compared to patients with <5% CPCs (median = 74 months, p < 0.001), and no significant difference in outcome was observed between patients with 5-20% and >20% (median = 38 months) CPCs. Patients with 1-5% CPCs (median = 50 months, HR = 2.45, 95% CI = 1.64 - 3.69, p < 0.001) also exhibited poor OS outcomes compared to patients with <1% CPCs (median = 74 months), suggesting that patients with >1% CPCs are a higher risk population, even if they do not meet the PCL threshold. Using a cutoff of >5% CPCs, 23/813 (2.8%) patients presented with primary PCL (pPCL) at diagnosis. Of these patients, 7 (30%) were hyperdiploid (HRD), of whom 1 had a CCND1 and 1 had a MYC translocation; while 16 (70%) were nonhyperdiploid (NHRD), all of whom had a canonical immunoglobulin translocation (6 CCND1, 5 WHSC1, 3 MAF, 1 MAFA, and 1 MAFB). Of 124 patients with serial sample collections, 5 (4%) patients without pPCL had >5% CPCs at progression, and thus relapsed with secondary PCL (sPCL). Of the 5 sPCL patients, 2 (40%) were NHRD with a CCND1 or MAF translocation; while 3 (60%) were HRD, 1 with a WHSC1 translocation. Median time to diagnosis of sPCL was 22 months (range = 2 - 31 months), and patients with sPCL (median = 22 months) and pPCL (median = 30 months) exhibited poor OS outcomes as compared to MM patients (74 months, p < 0.001). Sequencing data was available for 15 pPCL and 5 sPCL samples. For 12 patients with WES, WGS, and RNAseq performed on their PCL tumor sample, an integrated analysis identified recurrent, complete loss-of-function (LOF) events in only CDKN2C/FAF1, SETD2, and TRAF3. Five pPCL patients had complete LOF of a gene involved in G1/S cell cycle control, including CDKN2C, CDKN2A, CDKN1C, and ATM. These LOF events were not observed in NHRD t(11;14) PCL patients, suggesting that CCND1 overexpression and LOF of genes involved in G1/S cell cycle control may represent independent drivers of PCL. Comparing WES and WGS data between matched MM and PCL tumor samples revealed a high degree of similarity in mutation and copy number profile. However, differential expression analysis performed for 13 patients with RNAseq data comparing their MM and PCL tumors revealed 27 up- and 39 downregulated genes (padj < 0.01, FDR = 0.1) in PCL versus MM. Pathway analysis revealed an enrichment (p < 0.001) for genes involved in adhesion and diapedesis, including upregulation of ITGB2, PF4, and PPBP, and downregulation of CCL8, CXCL12, MMP19, and VCAM1. The most significantly downregulated gene in PCL (log2FC = -6.98) was VCAM1, which plays a role in cell adhesion, and where loss of expression (TPM < 0.01) was observed across all PCL samples. Upregulation of four S100 genes including S100A8, S100A9, S100A12, and S100P, which have been implicated in tumor growth, metastasis, and immune evasion, was also observed in PCL. Interestingly, a S100A9 inhibitor has been developed and may represent a novel treatment option for PCL patients. In summary, PCL was found to be associated with molecular events dysregulating G1/S cell cycle control coupled with subtle changes in transcription that likely occur in a subclonal population of the MM tumor. Disclosures Lonial: Genentech: Consultancy; GSK: Consultancy; BMS: Consultancy; Janssen: Consultancy, Research Funding; Karyopharm: Consultancy; Takeda: Consultancy, Research Funding; Celgene Corporation: Consultancy, Research Funding; Amgen: Consultancy.

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