ALBERT

Description: Introduction Our previous work showed that in Multiple Myeloma (MM) the immune function is impaired, including immunosuppressive properties of granulocytes due to their increased amount of arginase-1 and reduced phagocytic activity (Parrinello, manuscript in preparation). It is currently unknown if granulocyte dysfunction occurs in progression from MGUS to MM. Aim Providing a gene expression profile of mature granulocytes isolated from peripheral blood at the steady-statein MGUS and MM. Methods Using oligonucleotide microarrays we first evaluated the gene expression profile of granulocytes at the steady state in 5 MM, 3 MGUS and 3 healthy subjects matched for sex and age. Then, we validated the first up-regulated gene PROK-2, obtained from preliminary findings in granulocytes from peripheral blood in 85 consecutive newly diagnosed MGUS (N=45), MM (N=40) and 15 healthy subjects, in RT-PCR (validation set). Results We found 708 genes differentially expressed (467 up- and 241 down regulated) in MGUS versus healthy granulocytes at the steady state. The set of annotated, differentially expressed genes could befunctionally organized by “gene ontology” (http://www.geneontology.org/) into the following major categories: i) receptors and signal transduction (including up-regulation of CD14, Toll-like receptor 5 (TLR-5), IL-7 Receptor (CD127), IL-11 receptor, TGF-beta receptor 2, hematopoietic cells kinase (HCK), IFNAR1); ii) negative regulation of adaptive immune response (including up regulation of CD127, STAT6, IFNAR1, OSCAR, PROK-2 and down regulation of p50, p65,NFKBIA, IL8, ELK-1, HIF-1 alpha, CEBP-beta, CEBP-zeta). In MM samples we confirmed a statistically significant up-regulation of PROK-2 (a key molecule of VEGF-independent angiogenesis), CD14 (mediator hypersensitive innate immune response to lipopolysaccharide) and HCK (the hematopoietic cell kinase, involved in neutrophil migration and degranulation). In the validation set, PROK-2 expression was two times higher in MGUS than healthy subjects (p=.02) and up to ten times higher in MM (p=.001). In MM patients, increased levels of PROK-2 were positively associated with advanced bone disease and unfavourable cytogenetics. Conclusion Granulocytic impairment is present in MGUS and worsened in MM patients due to increased expression of genes that negatively regulate adaptive immune response. PROK-2 is a key molecule involved in the granulocyte dysfunction and could be involved in the progression from MGUS to MM. Disclosures Musto: Celgene: Honoraria; Janssen: Honoraria.

Description: Abstract 2926 Introduction Angiogenesis plays a central role in the progression of both solid and hematological tumors. In particular, in multiple myeloma (MM) the critical role of bone marrow (BM) microenvironment and angiogenesis has been well documented. The past decade has witnessed a dramatic improvement in the therapeutic options in MM. However, the disease remains incurable, underscoring the need for continued efforts towards understanding MM biology and exploitation of novel therapeutic approaches. In this setting, monoclonal antibodies against myeloma-specific cell surface antigens represent a promising therapeutic approach, which is however hampered by a lack of appropriate target structures expressed across all pathogenic myeloma cells. The Eph receptors, a large family of receptor tyrosine kinases (RTKs) activated by ephrins binding, have been implicated in many processes involved in malignancy, including alteration of the tumor microenvironment and in angiogenesis, in both of which EpHA3 likely plays an active role. Aberrant expression of EpHA3 is seen in many types of hematolologic malignancies (some leukemic cell lines, T-cell lymphoma, acute lymphoblastic leukemia, myeloproliferative neoplasms) although it is not expressed ubiquitously. Finally, the over-expression of Eph is believed to be sufficient to confer tumorigenic potential although probably further mechanisms can occur to abnormally activate the receptor. Basing on the role of EpHA3 in haematological malignancies, a first-in-class engineered IgG1 antibody targeting the EpHA (KB004) was developed and it is now under phase I clinical trials in USA and Australia for the treatment of EpHA3 overexpressing hematological myeloid malignancies refractory to conventional treatment. We investigated the EpHA3 role and its preferential membrane–bound by GPI linker ligand EFNA5, in MM patients in order to define EpHA3 as new molecular target for a novel therapeutic approach with a specific anti EpHA3 monoclonal antibody. The EpHA3 expression has been studied through a comparative proteomic analysis between BM endothelial cells (ECs) of patients with MM (MMECs) or with monoclonal gammopathy of undetermined significance (MGECs), of control subjects (normal ECs) and in MM cell lines. Methods After written informed consent, BM aspirates have been collected from 20 MM and 4 MGUS patients. Normal ECs were derived from 3 BM aspirates of subjects with anemia due to iron or vitamin B12 deficiency. We analyzed the expression levels of EpHA3 in normal ECs, MGECs and MMECs and MM cell lines evaluating the mRNA and protein levels by RT-qPCR and by WB coupled to ImmunoFluorescence analysis. The biological effects of EpHA3 targeting in MMECs have been studied silencing the EpHA3 mRNA in MMECs and testing them at 72h after silencing in series of functinal assays including viability assay by trypan blue exclusion staining and by in vitro angiogenesis assay followed by measurement of mesh areas and vessel length. Moreover, we studied EFNA5 mRNA expression levels in Normal ECs, MGECs and MMECs and in MM cell lines by PCR. Results Our data showed that EpHA3 mRNA levels are progressively increased from ECs to MGECs reaching the highest values in MMECs. Subsequent analysis by WB and immunofluorescence confirmed EpHA3 protein upregulation among the different EC types. The MMECs in which EpHA3 has been silenced revealed a protein level reduction of approximately 60% when compared to the control. We could not detect major viability defects. Furthermore, in vitro angiogenesis inhibition was marginal when compared to the not silenced counterpart. To know whether EpHA3 may impact not only MM angiogenesis but also plasma cells, three MM cell lines were studied for the EpHA3 expression. We found the plasma cell lines gave constant over expression of EpHA3. Finally, the preliminary data regarding EFNA5 mRNA expression level showed it is expressed in either MMECs and MM plasma cell lines. The evaluation of KB004 effect on MMECs in term of apoptosis induction and in vitro tube formation inhibition, as well as the analysis of EpHA3 levels in primary MM plasma cells are in progress. Conclusions From this study we expect to characterize the role of the EpHA3in MM patients and to provide experimental evidences supporting the possibility of using EpHA3 as a new molecular target for MM by proving the in vitro efficacy of a monoclonal antibody to target the angiogenesis of MM. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction Hematopoietic stem cells (HSC) are used in transplantation for the treatment of several hematological or non-hematological diseases. HSC fate is bound to different factors and, among these, the cross-talk with the bone marrow microenvironment represents an important regulatory mechanism of aging, self-renewal, stemness and/or differentiation. Cells communicate by both direct interaction and through the secretion of soluble factor and extracellular vesicles (EVs). EVs are cell-derived vesicles enclosed by a lipid bilayer and enriched in phosphatidylserine, cytoplasmic protein, mRNA, miRNA and DNA. Recent studies suggest that the release of EVs is a highly regulated and important process for surface membrane traffic and horizontal transfer of RNAs, protein and DNA, present in different kind of cells, including tumor cells. Bone marrow mesenchimal stem cells (BM-MSC) are a component of hematopoietic microenvironment and support hematopoiesis by the constitutive ability to secrete soluble factor and EVs. On these basis, we decided to study the interaction between the umbilical cord blood (UCBs) stem cells and the BM-MSCs mediated by EVs. The overarching goal of this project was to find out if and how the EVs can influence the fate of UCBs in transplantation. Methods Primary BM-MSC were cultured in DMEM containing 10% of fetal bovine serum (FBS). EVs were isolated from supernatant of BM-MSC by ultracentrifugation at 100.000 x g for 70 min at 4 ºC. After characterization by FACS analysis, EVs were stocked at -80 ºC and partially used for RNA extraction using TRIZOL reagent. EVs smallRNA was sequenced with HiScan SQ Illumina. UCBs CD34+ cells were isolated by Miltenyi Biotec separation kit and were cultured in DMEM containing 10% of FBS with or without BM-MSC EVs. After 24h of co-culture, viability by trypan blue count, apoptosis by Propide Iodure and Annexin V test and cell differentiation by FACS analysis of different markers (CD45, CD34, CD33, CD19 and CD38) were evaluated. RNA was extracted from the same samples and a gene expression profile experiment was performed using Illumina array. All genomic data were analyzed by Ingenuity Pathways Analysis software (IPA). Results EVs isolated from BM-MSC were positive for MSC markers like CD29 (61%), CD90 (72%), CD73 (63%), CD105 (35%), CD146 (32%), CD44 (70%) and for the exosome antigen CD81 (40%); they were negative, instead, for the hematopoietic marker CD45. The sequencing of smallRNA-EVs identified 87 miRNAs in BM-MSC EVs. Analysis of gene expression profile of UCBs CD34+ cells treated with EVs revealed 103 up-regulated and 100 down-regulated genes (with padj 〈 0.05 and logFC=0.7), when compared to UCBs CD34+ cells not treated with EVs. Interestingly, analyzing together the sequencing of EVs and the gene expression data of UCBs CD34+ cells treated with EVs, we found a direct correlation between EVs miRNAs and down-regulated genes, identifying at least one target gene for each EVs miRNA (e.g., miR-3168/LYZ, miR-27b-3p/ZFP36, miR21-5p/ANXA1). These results indicate that the EVs RNA content modifies the genes profile of receiving cells. Gene ontology analysis, using IPA, of the miRNA targeted genes identified different down-regulated biological function, like cell death and cellular development (e.g., CDKN1B, CEBPA, ANXA1, MPL). To confirm these data, we evaluated viability and apoptosis of UCBs treated with EVs respect to the UCBs control culture, and we observed an increase of 50% of cell viability and a reduction of 42% of apoptosis (p

Description: Introduction Multiple myeloma (MM) remains an incurable malignancy despite important recent advances in treatments. Neo-vascularization entails a crucial aspect of interactions between neoplastic plasma cells (PCs) and their microenvironment. Without it, MM would be unable to grow and progress, and would probably regress to a low-mass steady-state comparable to monoclonal gammopathy of undetermined significance (MGUS). To overcome drug resistance and improve clinical response to novel therapeutic approaches halting both PC growth and the increased bone marrow (BM) microvascular density are needed. In this setting, monoclonal antibodies against MM-specific cell surface antigens represent a promising therapeutic approach, which is however hampered by a lack of appropriate membrane target structures expressed across all MM cells. The Eph receptors, a large family of receptor tyrosine kinases, have been implicated in many processes involved in malignancy, including alteration of the tumour microenvironment, and in angiogenesis, in both of which EphA3 likely plays an active role. Interestingly, the over-expression of EphA3 is sufficient to confer tumorigenic potential, although probably further mechanisms can occur to abnormally activate the receptor. A first-in-class engineered IgG1 antibody targeting the EphA3 was developed and it is now under phase I clinical trials in USA and Australia for the treatment of EphA3 over-expressing hematological myeloid malignancies refractory to conventional treatment. Methods We investigated the EphA3 role in MM patients in order to define whether it may represent a potential new molecular target for a novel therapeutic approach with a specific anti EphA3 monoclonal antibody. The EphA3 expression was studied through a comparative proteomic analysis between BM endothelial cells (ECs) of patients with MM (MMECs) or with MGUS (MGECs), of control subjects (normal ECs). Moreover, the effects of anti EphA3 antibody in MM were studied in vitro and in vivo in a MM xenograft mouse model. After written informed consent, BM aspirates were collected from 26 MM and 6MGUS patients. Normal ECs were derived from 5 BM aspirates of subjects with anemia due to iron or vitamin B12 deficiency. We analyzed both mRNA and protein levels of EphA3 in normal ECs, MGECs and MMECs and in MM cell lines by absolute RT-PCR and by WB coupled to immunofluorescence and FACS analysis respectively. Immunoistochemistry was also performed on MM BM biopsies. The biological effects of EphA3 targeting were studied in vitro silencing (siRNA) the EphA3 mRNA in MMECs and using the anti EphA3 antibody testing them in series of in vitro functional assays including viability, apoptosis, adhesion, migration, wound healing and angiogenesis tests. We further examined the inhibitory capacity of anti-EphA3 Ab on tumor growth in SCID mice bearing MM tumor cell xenografts. Finally, we assessed morphology, vessel density, and apoptosis of excised xenotransplanted tumors. Results Briefly, our data showed that EphA3 mRNA and protein levels are progressively increased from ECs to MGECs, reaching the highest values in MMECs. EphA3 stained intensely and diffusely MM microvessels and PC in MM BM biopsies. The EphA3siRNA MMECs revealed a protein level reduction of approximately 80% when compared to the control. We not detected viability or apoptotic defects, whereas in vitro adhesion, migration and angiogenesis inhibition was evident when compared to the not silenced counterpart. The anti EphA3 antibody inhibited MMECs migration and reduced in vitro MM angiogenesis. In particular, tumour masses developed in xenograft mice treated with anti-EphA3 Abs were smaller in size and showed foci of ischemic-hemorrhagic necrosis, in association with a significant (P 〈 0.05) reduction in the number of intact tumor microvessels. The proliferative activity was not significantly different from that observed in tumors from untreated or control isotype treated mice, while the apoptotic index was significantly (P 〈 0.05) increased in comparison with tumors from both groups of mice. Conclusions In this study we have characterized the role of the EphA3in MM patients, providing in vitro and in vivo experimental evidences that support the possibility of using EphA3 as a new molecular target for MM. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 729 Introduction: The prognosis of primary plasma cell leukemia (PPCL) remains poor. The “novel agents” have recently shown promising results in PPCL patients in case reports or small retrospective series. Here we describe the first prospective, multicenter, phase II clinical trial of PPCL, where lenalidomide in combination with low dose dexamethasone (Ld) was tested as initial therapy in newly diagnosed patients fulfilling the IMWG diagnostic criteria of PPCL. Patients and methods: Ld regimen consisted of lenalidomide 25 mg/d for 21 days and oral dexamethasone 40 mg on days 1, 8, 15, and 22 for each 28-day cycle. After 4 cycles, responding patients not eligible for stem cell transplantation (SCT) continued until 8 cycles of full-dose Ld, followed by a maintenance dose of single agent lenalidomide equal to 10 mg/d on days 1–21 of each 28-day cycle. Patients responding after 4 cycles and eligible for SCT proceeded according to the treatment centre's transplant policy. Patients not responding after 4 cycles or progressing during this treatment were considered off-study. Appropriate dose reductions (in particular for patients with reduced renal function at baseline), double contraception methods and anti-thrombotic/anti-infective prophylaxis were recommended. The primary end-point was early response rate according to IMWG uniform response criteria. Secondary end-points were PFS, OS, feasibility and efficacy of SCT, safety. Results: According to the Simon optimal two-stage adaptive design, twenty-three patients were enrolled in between March 2009 and May 2011. The male/female ratio was 1.1, and median age was 60 years (range 44–80). The median absolute number and percentage of circulating plasma cells were 4.280/μl (range 1.500–114.660) and 34% (range 21–90) respectively. Fifteen patients (65.2%) had abnormal renal function at presentation. Twenty-one patients (91.3%) were tested by FISH analysis and cytogenetic abnormalities were detected in all of them, del13q being the most frequently found (16 patients). Seventeen patients showed multiple chromosomal lesions. Involvement of chromosome 14 was observed in 18 patients, three of whom showed t(4;14). Chromosome 1q gain and del17p were detected in 10 and 7 patients, respectively. In the intention-to-treat (ITT) population, overall response rate (ORR) after at least one Ld cycle was 73.9% (17/23), with 8 patients (34.7%) achieving partial remission (PR), 5 (21.7%) very good PR (VGPR), 3 (13%) complete response (CR), and 1(4.3%) near CR (nCR) (VGPR or better: 39%). In the efficacy-evaluable (EE) population, 14 out of 15 patients who received the initially planned 4 Ld cycles (65.2% of the ITT population) responded (ORR 93.3%), achieving 5 PR (33.3%), 5 VGPR (33.3%), 1 near-CR (6.6%) and 3 CR (20%) (VGPR or better: 59.9%). The maintenance phase was reached and safely performed in 4 responding patients not eligible for SCT, 3 of whom relapsed after 2, 8 and 22 months, respectively. After Ld induction therapy, 8 patients received single (n. 4) or double (n. 4) autologous SCT (ASCT); another patient underwent a sequence of ASCT followed by non-myeloablative allogeneic SCT (AlloSCT). Six eligible patients did not receive ASCT frontline, due to initial Ld failure or adverse events; three of them underwent single ASCT (n. 2) or tandem ASCT/non-myeloablative AlloSCT (n. 1) after a bortezomib-based salvage therapy, achieving 2 CR and 1 PR. After a median follow-up of 23 months, median OS and PFS in ITT population were not reached and 22 months, respectively. All transplanted patients remained alive, although three of them relapsed and started salvage treatments; OS was 12 months in the 11 patients who did not receive ASCT (p 〈 0.001). The correspondent figures for PFS were 29 and 16 months, respectively (p 〈 0.01). Considering ITT population, multivariate analyses showed that SCT was positively correlated to both OS and PFS. There were 17 episodes of grade 3/4 non hematological toxicity, which occurred in 13 patients (5 infections, 3 renal, 3 metabolic, 2 gastro-intestinal, 2 skin, 1 fatigue, 1 thromboembolic), causing early interruption of Ld treatment in 4 patients. Grade 3/4 hematological toxicity (mainly neutropenia) occurred in 11 patients (47.8%). Conclusions: Ld may be a feasible and effective initial therapeutic option for PPCL, particularly in patients who receive ASCT after a short course of induction treatment. Disclosures: Musto: Celgene: Honoraria, Research Funding. Off Label Use: Lenalidomide as first line therapy of plasma cell leukemia. Petrucci:Celgene: Honoraria. Cascavilla:Celgene: Honoraria. Di Raimondo:Celgene: Honoraria. Caravita:Celgene: Honoraria. Morabito:Celgene: Honoraria. Offidani:Celgene: Honoraria. Bringhen:Celgene: Honoraria. Boccadoro:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Palumbo:Celgene: Consultancy, Honoraria.

Description: INTRODUCTION: Extracellular vesicles (EVs), including exosomes, shedding vesicles (microvesicles: MVs) and apoptotic bodies, are membrane vesicles of 40-3,000 nm that are released from many cell types, such as red blood cells, platelets, lymphocytes, dendritic cells, endothelial cells and tumour cells. They have a key role not only in the regulation of normal physiological processes, but also in the pathology underlying several diseases. Recently, it was discovered that EVs circulate in bodily fluids of cancer patients and could serve as potential diagnostic biomarkers. However, the presence and role of peripheral circulating EVs in hematological malignancies (HMs) remain unclear. The aim of this study was to investigate EVs in peripheral blood of HM patients, defining the EVs count, size and phenotype. METHODS: Peripheral blood samples were obtained prior to treatment from 87 subjects: 6 Chronic Lymphocytic Leukemia (CLL), 10 Non-Hodgkin's Lymphoma (NHL; 5 follicular, 5 diffuse large B-cell), 6 Waldenstrom's Macroglobulinemia (WM), 6 Hodgkin's Lymphoma (HL), 6 Multiple Myeloma (MM), 5 Acute Myeloid Lukemia (AML), 19 Myeloproliferative Neoplasms [(MPNs; 5 Essential Thrombocythemia (ET), 5 Polycythemia Vera (PV), 5 Primary Myelofibrosis (PMF), 4 Chronic Myelogenous Leukemia (CML)], 5 Myelodysplastic Syndrome (MDS) and 28 healthy controls. EVs were isolated from serum of peripheral blood by ultracentrifugation steps. For calculation of counts, TruCOUNT beads were added immediately prior to analysis by flow cytometry (FACS). For size assessment, Megamix beads with specific size (0.3,0.9, 3.0 micrometer) were used. For phenotype characterization, a panel of specific antibodies (anti CD59, CD61, CD62E, CD19, CD20, CD38, CD138, CD13, CD30) were employed in a FACS analysis. RESULTS: MVs count was significantly higher in patients with CLL, WM, HL, MM, AML and CML (median values 890, 3227, 1218, 914, 656 and 1275 MVs/microliter of serum, respectively) compared to healthy controls (median value 270 MVs/ microliter of serum, ***P