bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myeloid-Derived Suppressor Cells in Multiple Myeloma.
Authors: Van Valckenborgh Els , Van Ginderachter Jo , Movahedi Kiavash , Menu Eline , Vanderkerken Karin 
Published: October 2019

Abstract
Abstract 2794
Poster Board II-770
Myeloid-derived suppressor cells (MDSCs) are a heterogeneous mix of myeloid cells in different maturation stages generated in the bone marrow. The role of MDSCs in cancer is to suppress T-cell responses, thereby likely regulating tumor progression. In mice, MDSCs are identified by the expression of the surface markers CD11b and Gr-1. Recently, Ly6G+ granulocytic (PMN-MDSC) and Ly6G− monocytic (MO-MDSC) subsets could be distinguished (Movahedi et al. Blood 2008, 111:4233-44). In multiple myeloma patients, the immune function is impaired and this is caused by an immunologically hostile microenvironment and cellular defects, such as decreased numbers of immune cells, and DC or T-cell dysfunction. However, the role of MDSCs in immune suppression in multiple myeloma is not yet described.
In this study, we investigated the immunosuppressive activity and mechanism of MDSC subsets in the syngeneic and immunocompetent 5TMM mouse model (5T2 and 5T33 models). In first instance, CD11b+Ly6G− and CD11b+Ly6G+ lineage-committed myeloid MDSC subsets were detected in 5TMM-diseased bone marrow by flow cytometry. These subsets were purified via MACS from the bone marrow of naïve and 5TMM tumor-bearing mice, and analyzed for T-cell suppressive activity. Hereto, CD8+ TCR-transgenic OT-1 splenocytes were stimulated with ovalbumin protein in the presence of purified MDSC subsets, after which T-cell proliferation was measured via 3H-thymidine incorporation. Both MDSC subsets from 5TMM bone marrow were able to suppress antigen-specific T-cell responses at a higher level compared to purified MDSC subsets from normal bone marrow. On average, Ly6G− MDSCs were more suppressive than Ly6G+ MDSCs. The 5T2MM model has a tumor take of approximately 12 weeks. Three weeks after intravenous inoculation of the tumor cells, the suppressive effect of the myeloid subsets was already observed (while the plasmacytosis in the BM was very low and no detectable serum M spike was observed), indicating that T-cell suppression is an early event in MM development. To unravel the suppressive mechanism of the MDSC subsets, inhibitors were used in ovalbumin-stimulated cocultures. Ly6G− MDSC-mediated suppression was partially reversed by the iNOS inhibitor L-NMMA and the COX-2 inhibitor sc-791, both of which lower the NO concentration in culture. In contrast, superoxide dismutase and especially catalase enhance NO concentrations, resulting in enhanced T-cell suppression. None of these inhibitors had any impact on the Ly6G+ MDSC-mediated suppression.
In conclusion, these data reveal the presence of MDSCs as a novel immune suppressive strategy employed by multiple myeloma cells in the bone marrow, already occurring early in the disease process.

Disclosures:
No relevant conflicts of interest to declare.
An Angiogenic Risk Score Improves the Prognostic Information of the International Staging System in Patients with Symptomatic Multiple Myeloma.
Authors: Jakob Christian , Wernecke Theresa , Sterz Jan , Goerke Andrea , Heider Ulrike , Kaiser Martin , Mieth Maren , Ziefle Susanne , Sezer Orhan 
Published: October 2019

Abstract
Abstract 2802
Poster Board II-778

Introduction:
Bone marrow angiogenesis has been shown to correlate with growth, disease progression and survival in multiple myeloma (MM). The angiogenic stimulus in the bone marrow microenvironment is mediated by various angiogenic factors. Serum levels of the angiogenic cytokines basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) can be elevated in MM patients in different disease stages.

Patients and methods:
In the present study we investigated the prognostic value of circulating levels of serum-bFGF, serum-HGF and plasma-VEGF by enzyme-immunoassays in 100 newly diagnosed MM patients, 24 with smoldering MM and 76 patients with symptomatic MM. In addition, the parameters of the recently introduced International Staging System (ISS), beta-2-microglobulin (β2M) and albumin were evaluated in comparison to the angiogenic cytokines in a multivariate prognostic model.

Results:
Circulating levels of serum bFGF, serum HGF and plasma VEGF were significantly elevated in symptomatic versus smoldering MM (P= 0.015, P= 0.005 and P=0.015 respectively). In a univariate survival analysis, all angiogenic factors and a combined angiogenic cytokine score (0-1 versus 2-3 angiogenic factors elevated) were identified as significant prognostic factors for overall survival in the total cohort of MM patients (P= 0.046, P= 0.005 and P< 0.009, respectively) and in symptomatic MM (P= 0.025, P< 0.001 and P= 0.018, respectively). In addition to angiogenic cytokine levels, beta-2-microglobulin (β2M) and albumin as parameters of the ISS were also entered in a multivariate analysis. In this model, bFGF, HGF and VEGF were found to be independent prognostic factors (hazard ratio: 2.5, 3.6 and 2.6, respectively) in symptomatic MM (Table 1). A combined angiogenic risk score (0-1 or 2-3 angiogenic factors elevated) was also a significant prognosticator for overall survival in symptomatic MM (P< 0.001) and clearly separated two subgroups with a good and a worse prognosis within ISS stage III (P= 0.003). In patients with a high angiogenic risk score (2 or 3 factors elevated) there was no significant survival benefit of high-dose therapy, in contrast to patients with a low risk score (0-1 factors elevated).

Conclusions:
Our data show that elevated angiogenic cytokines predict poor prognosis and gives additional prognostic information in comparison to the ISS parameters β2M and albumin in symptomatic MM. Since a variety of drugs with anti-angiogenic properties are currently in use or under investigation in MM, our data support the idea of using angiogenic cytokines as risk factors to identify poor prognosis groups, which may be considered for novel anti-angiogenic treatment strategies.

Disclosures:
No relevant conflicts of interest to declare.
The Krüppel-Like Factor 4 (KLF4) Modulates Survival and Tissue Distribution of Natural Killer Cells.
Authors: Shik Park Chun , Lee Ping-Hsien , Yamada Takeshi , Mamonkin Maksim , Lacorazza H. Daniel 
Published: October 2019

Abstract
Abstract 282
Natural Killer (NK) cells are important mediators of the innate immune system that could be targeted therapeutically to treat hematologic malignancies and to prevent graft-versus-host disease. Hence, a better understanding of NK cell survival and tissue trafficking at steady state is vital to develop cell-based therapies. Genes that control proliferation are often involved in tissue distribution of lymphocytes, such as KLF2 in T cells. KLF4, another member of the Krüppel-like factor family, can activate and repress genes involved in diverse cellular processes. We recently reported that KLF4 is part of a novel inhibitory pathway that prevents proliferation of naïve T cells during homeostasis and retain memory T cells in lymph nodes (Yamada et al., Nature Immunology, 2009). In this work, we studied the role of KLF4 in the development and maintenance of NK cells by deleting Klf4-floxed gene (fl/fl) using the Mx1-Cre system. The percentage of NK1.1+TCR- cells is significantly reduced in peripheral blood of Klf4-deficient (▪/▪) mice (fl/fl: 3.4±1.1 versus ▪/▪: 1.2±0.1, n=9) and also absolute numbers in spleen (▪/▪: 1.1±1.3 ×106, n=6) due to increased percentage of Annexin V positive cells (fl/fl: 9.2±3.2 versus ▪/▪: 22.9±15.5, n=15). The number of CD49d+TCR- cells was also significantly reduced in peripheral blood and spleen of Klf4-deficient mice. In contrast, the number of NK cells in bone marrow and lymph nodes of Klf4-deficient mice was similar to controls. Deletion of Klf4 gene led to reduced numbers of NK1.1+TCR-CD27+CD11b+ and NK1.1+TCR-CD27-CD11b+ cells, which correlated with increasing apoptosis of these subsets. Yet, the percentages of these NK cell subsets were normal in bone marrow ruling out a developmental defect in this tissue. Transplant of wild type and Klf4-deficient bone marrow cells into wild type mice suggested environmental rather than cell intrinsic defects. NK cells (NK1.1+TCR-) isolated from spleen of Klf4-deficient mice showed to be functional in a cytotoxicity assay using a mixture of differentially CFSE-labeled RMA-S (target) and EL4 (control). In summary, KLF4 plays a key role in the maintenance of mature NK cells in peripheral blood and spleen.

Disclosures:
No relevant conflicts of interest to declare.
Patterns of Monoclonal Immunoglobulins and Serum Free Light Chains Are Significantly Different in African-American Compared to Caucasian MGUS Patients.
Authors: Weiss Brendan , Minter Alex , Laquer Matthew , Howard Robin , Abadie Jude , Ascencao Joao , Schechter Geraldine P. , Kuehl Michael , Landgren Ola 
Published: October 2019

Abstract
Abstract 2838
Poster Board II-814

Background.
Monoclonal gammopathy of undetermined significance (MGUS), the precursor of multiple myeloma (MM), is 2- to 3-fold more common in African-Americans (AA) than Caucasians (CA). Prior studies have reported clinical features of MGUS and MM to be different among AA compared to CA. Recent studies on CA MGUS cases have found serum free kappa and lambda light chain assays (sFLC) to be highly predictive of MM progression. We have conducted the first study designed to evaluate patterns of sFLC markers in AA.

Methods.
All AA MGUS patients seen at Walter Reed Army Medical Center (WR) and the Washington DC Veteran's Affairs Medical Center (VA) 2005-2009 were eligible. WR patients were enrolled through a retrospective chart review as sFLC has been performed routinely on MGUS patients. VA patients were enrolled in a prospective trial and sFLC was performed at WR. All patients were categorized for their risk of progression using the Mayo Clinic model (Rajkumar SV Blood 2005) and compared to the Caucasian Mayo Clinic population by the Fisher's exact test (2-tailed).

Results.
Eighty-six patients were enrolled, the median age was 73 yrs (42-92) and 74% were male. The MGUS isotype was 87% IgG, 10% IgA, 2% IgM and 1% biclonal. Kappa and lambda light chain disorders were present in 61% and 38%, respectively. The median monoclonal Ig concentration was 0.56 gm/dL (trace-2.33), 47% had a concentration '0.5 g/dL, 30% 0.51-1.0, 20% 1-2 g/dL, and 2% 2-3 g/dL. An abnormal sFLC ratio was present in 49% of patients. Based on the Mayo Clinic model, the risk of progression was: low 42% (95%CI 32-52), low-intermediate 49% (39-59), high-intermediate 8% (4-16) and high 1% (0-7). In comparing our data to the Mayo Clinic data, AA have significantly different distributions of MGUS isotype (p =0.001), lower monoclonal Ig concentration (p=0.0005), presence of an abnormal sFLC ratio (p=0.004) and distributions of Mayo Clinic risk groups (p=0.008) (see table).

Conclusions.
The clinical and laboratory features of AA patients with MGUS are distinctly different than in Caucasians, in particular a lower proportion of IgM MGUS, lower monoclonal Ig levels, a higher proportion of abnormal sFLC ratios, and fewer higher-risk patients. IgM MGUS is the precursor to Waldenstrom's macroglobulinemia (WM) and the lower proportion of IgM MGUS in AA is consistent with the very low rate of WM in AA. Non-IgM MGUS should be considered a separate entity and a direct comparison of AA and CA non-IgM MGUS patients using the Mayo Clinic data is planned. The significance of these differences on the risk of malignant progression will require prospective studies in racially diverse populations.

Disclosures:
Weiss: The Binding Site, Inc.: Research Funding.
Matrix Metalloproteinses-13 (Collagenase-3) Secreted by Multiple Myeloma Cells Enhances the Bone Resorptive Activity of Osteoclasts.
Authors: Feng Rentian , Kurihara Noriyoshi , Ma Huihui , Roodman G. David , Lentzsch Suzanne 
Published: October 2019

Abstract
Abstract 2853
Poster Board II-829

Introduction:
Osteolytic bone disease is a frequent complication of multiple myeloma (MM) that is characterized by reduced bone formation and increased bone resorption. MM cells produce several cytokines causing dysregulation of the bone remodeling process that results in excessive bone resorption mediated by activated osteoclasts (OCLs). Matrix metalloproteinases (MMPs) play a critical role in tumor invasion and progression in many solid tumors such as breast cancer but the role of MMPs in MM has have not been well elucidated.

Methods and Results:
We analyzed the MMP expression profiles (MMP1, 2, 3, 7, 8, 12, 13) of MM cells and found very high expression (400-fold higher) of MMP13 compared to other MMPs. Tissue array analysis for MMP-13 expression in MM tumor samples and normal control tissue indicated that MMP13 was only highly expressed in MM tumor samples. ELISA analysis of serum samples revealed a positive correlation of MMP13 expression with MM bone disease. MMP13 was not detectable in the sera of healthy donors, whereas 62% of MM patients expressed MMP13 in their serum samples, among which 87% had extensive bone disease. Co-culture of MM cells with primary bone marrow stromal cells (BMSC) resulted in a significant (P<0.001) increase (up to 14-fold) of MMP13 secretion by MM cells. RT-PCR analysis indicated that the expression of MMP13 gene in MM cells was markedly enhanced by BMSC conditioned medium, suggesting that BMSC-secreted soluble factors, instead of direct cellular interactions, induce MMP13. Functional inactivation of different cytokines with neutralizing antibodies identified IL-6 as a critical cytokine for the induction of MMP13. Electromobility shift assays showed that IL-6 mediated AP-1 activation promotes MMP13 transcription. Importantly, MMP13 significantly enhanced osteoclastic bone resorption on dentin slices induced by RANKL plus M-CSF. However, the strong induction of bone resorption was not derived from increased OCL formation since MMP13 only slightly increased OCL numbers. MMP13 significantly increased the OCL size as well as the nuclear number/OCL which increases the bone resorption activity per osteoclast.

Conclusions:
Our results suggest that MMP13 augments the pathogenic process of osteolytic lesions in MM by increasing the bone resorption capacity/OCL. These results suggest that targeting MMP13 may represent a novel approach to ameliorate osteolytic lesions in MM.

Disclosures:
Roodman: Novartis: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy; Celgene: Consultancy; Acceleron: Consultancy. Lentzsch:Celgene: Consultancy, Speakers Bureau; Pfizer: Consultancy.
Waldenstrom's Macroglobulinemia: A SEER Database Review From 1981-2005.
Authors: Sekhar Jeevan , Morgensztern Daniel , Zhang Qin , Vij Ravi 
Published: October 2019

Abstract
Abstract 2926
Poster Board II-902

Introduction:
Waldenstrom's Macroglobulinemia (WM) is a relatively rare hematopoietic neoplasm, with literature data mostly limited to small series of patients. We conducted a review of the Surveillance Epidemiology and End Results (SEER) database for WM analyzing 2969 cases from 1981-2005.

Results:
The incidence of reported cases of WM was stable during the studied time period at 0.3 per 100,000. The median age at diagnosis was 73 (range 23-98). There were 1661 male cases of WM and 1038 female cases (incidence ratio of 1.6:1). There were 2435 Caucasian cases and 264 non-Caucasian cases (incidence ratio of 9.2:1). Median overall survival for the entire cohort was 65 months (95% CI, 61-69). Five-year overall survival was 52% (95% CI, 50-55%). There was a significant difference in survival for individuals age <60 years versus age ≥60 years with age-adjusted 5 year overall survivals of 78% (95% CI, 44-49%) and 47% (95% CI, 44-49%), p<0.0001, respectively. Gender and race had no impact on overall survival (p=0.23 and 0.13, respectively). There was no improvement in survival over the time period analyzed. The cohort of patients diagnosed in 1981-1995 had a 5-year overall survival of 50% (95% CI, 46-54%), and those diagnosed in 1996-2005 had a 5-year overall survival of 54% (95%CI, 51-57%), p=0.18.

Conclusion:
This survey represents the largest cohort of WM analyzed to date. Age was shown to be the sole predictor of overall survival. Furthermore, these results underscore the little therapeutic progress we have made for this disease considering the lack of improvement in overall survival over a quarter century.

Disclosures:
Vij: Otsuka Pharmaceuticals: Research Funding.
Detection of LMO2 in Normal Human Tissues and Haematopoietic and Non-Haematopoietic Tumours by a Newly Developed Rabbit Monoclonal Antibody.
Authors: Agostinelli Claudio , Paterson Jennifer C , Gupta Rajeev , Righi Simona , Sandri Federica , Piccaluga Pier Paolo , Bacci Francesco , Sabattini Elena , Pileri Stefano A. , Marafioti Teresa 
Published: October 2019

Abstract
Abstract 2942
Poster Board II-918

Introduction:
LMO2 is a transcription factor with a central role in haematopoietic development and angiogenesis. High levels of LMO2 transcript were reported in CD34+ stem cells and strong protein expression was observed in endothelia, germinal centre B cells (GCB) and some B cell lymphomas. Activation of LMO2 has been demonstrated in T-ALL as a consequence of translocations or deletions and its expression in diffuse large B-cell lymphomas is associated with favourable outcome. Furthermore, correlation between LMO2 expression and tumour progression has been reported in prostatic carcinoma.

Aims:
The expression pattern of a newly developed rabbit monoclonal antibody raised against a fixation-resistant epitope of the LMO2 protein was studied in human normal and pathologic samples.

Material and Methods:
Normal haematopoietic and non-haematopoietic tissue sections, tissue micro-arrays including 1452 neoplastic samples, 11 lymphoma-derived cell lines and CD34+/CD38− stem cells, purified from human umbilical cord blood, were investigated by single and double immunostaining.

Results and discussion:
Strong LMO2 expression was found in CD34+/CD38− stem cells and in contrast to previous studies, the anti-LMO2 rabbit monoclonal distinctively labelled normal mantle, monocytoid and splenic marginal zone B cells. A few LMO2+/CD34+ cells were detected in the thymic cortex, most likely representing T cell precursors. Tables 1 and 2 summarise the results obtained in tumours and lymphoma-derived cell lines. Among B cell neoplasms, LMO2 was highly expressed in B-lymphoblastic lymphoma/leukaemia (87%) and heterogeneously in MCL (14%), FL (57%) and BL (37%). In DLBCL, LMO2 positivity was closely related to those cases with a “germinal centre” phenotype. LMO2 nuclear positivity was observed in all cases of LPHL; interestingly Reed-Sternberg cells in CHL showed LMO2 cytoplasmic staining in 10% of cases. The constant expression in T-ALL highlights the pathogenetic role and diagnostic significance of LMO2 in this setting as opposed to PTCLs (usually negative). Detection of LMO2 was observed in the majority of AML and CML cases investigated. Different types of carcinoma expressed LMO2 that was found to be mainly cytoplasmic.

Conclusion:
The newly developed anti-LMO2 rabbit monoclonal antibody represents a powerful reagent for detection of LMO2 protein in routine samples as compared to the previously published monoclonal anti-LMO2. Its frequent expression among haematological malignancies (e.g. T-ALL, B-ALL and AML) indicates LMO2 as putative therapeutic target as evidenced by RNA-silencing studies in experimental models.

Disclosures:
No relevant conflicts of interest to declare.
Minimal Disseminated Disease Is An Independent Poor Prognosis Marker Among High Risk Burkitt's Lymphoma Patients .
Authors: Mussolin Lara , Pillon Marta , Tridello Gloria , Boaro Maria Paola , d'Amore Emanuele S , Nigro Luca Lo , Buffardi Salvatore , Lombardi Alessandra , Sala Alessandra , Favre Claudio , Aricò Maurizio , Rosolen Angelo 
Published: October 2019

Abstract
Abstract 2944
Poster Board II-920

Introduction:
The chromosomal translocation t(8;14)(q24;q32) represents a specific tumor marker in Burkitt's lymphoma (BL). This chromosomal aberration involves the MYC oncogene on chromosome 8 and the immunoglobulin heavy-chain (IgH) locus on chromosome 14. We have previously demonstrated that this genetic abnormality can be used as a marker of Minimal Disseminated Disease (MDD) in BL (Mussolin et al, JCO, 2007). The aim of the study was to assess of the prevalence of MDD in BL at diagnosis in children enrolled in the AIEOP LNH-97 clinical protocol and the evaluation of its impact on prognosis.

Patients and Methods:
We established a simplified long-distance PCR (LD-PCR) assay which can amplify up to 15-20 Kb DNA sequence making it possible to detect the t(8;14) at the genomic level with the sensitivity of 10-4. The assay was based on 4 separate PCR reactions in which one primer complementary to the first exon of the MYC gene is used with one of four primers for the IgH locus (1 for the JH region and 1 for each of the 3 constant regions).

Results:
LD-PCR was applied to prospectively study 124 BL biopsies and detected a specific PCR product in 88 of them (71%). Of the 88 positive BL patients we studied both the tumor and the bone marrow (BM) at diagnosis in 76: BM was positive by LD-PCR in 25 patients (33%), whereas only 10 (13%) were positive at the standard morphological and/or immunophenotypical analyses. Most of the MDD positive patients (88%) belonged to the R4 Risk Group according to BFM definition (stage III or stage IV according to St. Jude staging classification and LDH≥1000 U/l). The 3-year progression-free survival (PFS) was 68% (SE 10%) in MDD positive R4 patients compared with 96% (SE 4%) in MDD negative R4 patients (p= 0.02), whereas there was no difference in PFS between children with morphological involvement of BM at diagnosis versus those who had negative BM (PFS=62.5% (SE 17%) vs. PFS= 87% (SE 6%), respectively, p= 0.09). By multivariate analysis (including MDD, gender, LDH, CNS involvement) MDD was predictive of higher risk of failure (Hazard Ratio: 8.4 , p= 0.04).

Conclusions:
We demonstrated that MDD identifies a poor prognosis subgroup among high risk Burkitt's lymphoma patients. We suggest that a more effective risk-adapted therapy, possibly including anti-CD20 monoclonal antibody, should be considered in these patients.

Disclosures:
No relevant conflicts of interest to declare.