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Neuroblastoma is the most common extracranial pediatric solid tumor with a heterogeneous clinical course, ranging from spontaneous regression to metastatic disease and death, irrespective of intensive chemotherapeutic regimen. On the basis of several parameters, children affected by neuroblastoma are stratified into low, intermediate and high risk. At present, more than 50% of high-risk patients with metastatic spread display an overall poor long-term outcome also complicated by devastating long-term morbidities. Thus, novel and more effective therapies are desperately needed to improve lifespan of high-risk patients. In this regard, adoptive cell therapy holds great promise and several clinical trials are ongoing, demonstrating safety and tolerability, with no toxicities. Starting from the immunological and clinical features of neuroblastoma, we here discuss the immunotherapeutic approaches currently adopted for high-risk patients and different innovative therapeutic strategies currently under investigation. The latter are based on the infusion of natural killer (NK) cells, as support of consolidation therapy in addition to standard treatments, or chimeric antigen receptor (CAR) T cells directed against neuroblastoma associated antigens (e.g., disialoganglioside GD2). Finally, future perspectives of adoptive cell therapies represented by γδ T lymphocyes and CAR NK cells are envisaged.

TcRαβ/CD19-cell depleted HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) represents a promising new platform for children affected by acute leukemia in need of an allograft and lacking a matched donor, disease recurrence being the main cause of treatment failure. The use of zoledronic acid to enhance TcRγδ+ lymphocyte function after TcRαβ/CD19-cell depleted haplo-HSCT was tested in an open-label, feasibility, proof-of-principle study. Forty-six children affected by high-risk acute leukemia underwent haplo-HSCT after removal of TcRαβ+ and CD19+ B lymphocytes. No post-transplant pharmacological graft-versus-host disease (GvHD) prophylaxis was given. Zoledronic acid was administered monthly at a dose of 0.05 mg/kg/dose (maximum dose 4 mg), starting from day +20 after transplantation. A total of 139 infusions were administered, with a mean of 3 infusions per patient. No severe adverse event was observed. Common side effects were represented by asymptomatic hypocalcemia and acute phase reactions (including fever, chills, malaise, and/or arthralgia) within 24–48 h from zoledronic acid infusion. The cumulative incidence of acute and chronic GvHD was 17.3% (all grade I-II) and 4.8% (all limited), respectively. Patients given 3 or more infusions of zoledronic acid had a lower incidence of both acute GvHD (8.8 vs. 41.6%, p = 0.015) and chronic GvHD (0 vs. 22.2%, p = 0.006). Transplant-related mortality (TRM) and relapse incidence at 3 years were 4.3 and 30.4%, respectively. Patients receiving repeated infusions of zoledronic acid had a lower TRM as compared to those receiving 1 or 2 administration of the drug (0 vs. 16.7%, p = 0.01). Five-year overall survival (OS) and disease-free survival (DFS) for the whole cohort were 67.2 and 65.2%, respectively, with a trend toward a better OS for patients receiving 3 or more infusions (73.1 vs. 50.0%, p = 0.05). The probability of GvHD/relapse-free survival was significantly worse in patients receiving 1–2 infusions of zoledonic acid than in those given ≥3 infusions (33.3 vs. 70.6%, respectively, p = 0.006). Multivariable analysis showed an independent positive effect on outcome given by repeated infusions of zoledronic acid (HR 0.27, p = 0.03). These data indicate that the use of zoledronic acid after TcRαβ/CD19-cell depleted haploHSCT is safe and may result in a lower incidence of acute GvHD, chronic GvHD, and TRM.

The importance of glutamine (Gln) metabolism in multiple myeloma (MM) cells and its potential role as a therapeutic target are still unknown, although it has been reported that human myeloma cell lines (HMCLs) are highly sensitive to Gln depletion. In this study, we found that both HMCLs and primary bone marrow (BM) CD138(+) cells produced large amounts of ammonium in the presence of Gln. MM patients have lower BM plasma Gln with higher ammonium and glutamate than patients with indolent monoclonal gammopathies. Interestingly, HMCLs expressed glutaminase (GLS1) and were sensitive to its inhibition, whereas they exhibited negligible expression of glutamine synthetase (GS). High GLS1 and low GS expression were also observed in primary CD138(+) cells. Gln-free incubation or treatment with the glutaminolytic enzyme l-asparaginase depleted the cell contents of Gln, glutamate, and the anaplerotic substrate 2-oxoglutarate, inhibiting MM cell growth. Consistent with the dependence of MM cells on extracellular Gln, a gene expression profile analysis, on both proprietary and published datasets, showed an increased expression of the Gln transporters SNAT1, ASCT2, and LAT1 by CD138(+) cells across the progression of monoclonal gammopathies. Among these transporters, only ASCT2 inhibition in HMCLs caused a marked decrease in Gln uptake and a significant fall in cell growth. Consistently, stable ASCT2 downregulation by a lentiviral approach inhibited HMCL growth in vitro and in a murine model. In conclusion, MM cells strictly depend on extracellular Gln and show features of Gln addiction. Therefore, the inhibition of Gln uptake is a new attractive therapeutic strategy for MM.

In a previous study, lack of IL-12 signaling in il12rb2 knock-out mice was found to predispose to lung adenocarcinoma (LAC). We asked whether specific polymorphisms of the human IL12RB2 gene may confer susceptibility to LAC. We studied IL12RB2 single nucleotide polymorphisms (SNPs) spanning from the promoter to the first untranslated exon of the gene. Genotypes of 49 individuals with LAC were compared with those of 93 healthy subjects. Two allele variants were found to be associated with increased susceptibility to LAC. One haplotype (hap), hap18, was more frequent in patients (18%) versus controls (6%) and significantly associated with increased probability of disease occurrence. Furthermore, IL-12 driven STAT4 phosphorylation in T cell blasts from healthy individuals was found to correlate with both single allele variants and haplotypes. In conclusion, genetically determined low signaling activity of IL-12R predisposes to the development of LAC.

Most studies on genetic engineering technologies for cancer immunotherapy based on allogeneic donors have focused on adaptive immunity. However, the main limitation of such approaches is that they can lead to severe graft-versus-host disease (GvHD). An alternative approach would bolster innate immunity by relying on the natural tropism of some subsets of the innate immune system, such as γδ T and natural killer (NK) cells, for the tumor microenvironment and their ability to kill in a major histocompatibility complex (MHC)-independent manner. γδ T and NK cells have the unique ability to bridge innate and adaptive immunity while responding to a broad range of tumors. Considering these properties, γδ T and NK cells represent ideal sources for developing allogeneic cell therapies. Recently, significant efforts have been made to exploit the intrinsic anti-tumor capacity of these cells for treating hematologic and solid malignancies using genetic engineering approaches such as chimeric antigen receptor (CAR) and T cell receptor (TCR). Here, we review over 30 studies on these two approaches that use γδ T and NK cells in adoptive cell therapy (ACT) for treating cancer. Based on those studies, we propose several promising strategies to optimize the clinical translation of these approaches.

Background & Aim Viral infections remain a leading cause of morbidity and mortality after transplantation. Although prophylactic pharmacotherapy is effective in reducing the risk for some viral infections, therapeutic options for breakthrough infections are still unsatisfactory. Conventional pharmacologic agents against Adenovirus (AdV) and Epstein-Barr virus (EBV) have limited efficacy and relevant toxicity, whereas in the case of cytomegalovirus (CMV) are documented better response rates, but toxicity and reactivation after treatment stop are frequent. T-cell reconstitution is a key requirement for effective antiviral control following transplantation, and factors that influence the speed of T-cell recovery impact also the risk of viral infection in this period. The use of lymphocyte infusions derived from seropositive donors is an effective salvage therapy for viral infections in transplanted recipients prior to T-cell recovery, but the risk of severe graft-versus-host disease (GVHD) is a critical concern. Thus, we propose a novel immunotherapeutic approach based on gd T cells specific for AdV, CMV and EBV. Many studies highlighted the importance of gd T cells in antiviral immunity, uniquely combining conventional adaptive features with rapid, innate-like responses. These lymphocytes are effector cells that: i) recognize target cells in a MHC-independent manner, thus do not cause GvHD; ii) participate CMV and EBV responses, particularly when conventional adaptive immunity is insufficient to clear the viral infection; iii) may develop memory responses, and iv) cross-talk with other immune cells, including NK lymphocytes, alfa beta T cells and dendritic cells. These features render gd T cells extremely appealing for clinical purposes. We believe that an ATMP containing Vd1 and Vd2 gd T cells will be the ideal immunotherapeutic approach to prevent and treat viral infections after transplantation. Methods, Results & Conclusion To this end, we are developing a new method to obtain a cell product containing expanded Vd1 and Vd2 gd T cells using exclusively GMP-graded reagents, including zoledronic acid, cytokines, viral peptides (related to AdV, CMV and EBV) and ab depletion techniques. Such cell product has been tested for i) phenotype, ii) allo-reactivity, iii) cytotoxicity and iv) specificity. Our preliminary results strongly support the feasibility for development of new immunotherapeutic protocols using gd T cells, with the aim of preventing and treating viral infections after transplantation.

We demonstrated that γδ T cells of patients given HLA-haploidentical HSCT after removal of αβ+ T cells and CD19+ B cells are endowed with the capacity of killing leukemia cells after ex vivo treatment with zoledronic acid (ZOL). Thus, we tested the hypothesis that infusion of ZOL in patients receiving this type of graft may enhance γδ T-cell cytotoxic activity against leukemia cells. ZOL was infused every 28 d in 43 patients; most were treated at least twice. γδ T cells before and after ZOL treatments were studied in 33 of these 43 patients, till at least 7 mo after HSCT by high-resolution mass spectrometry, flow-cytometry, and degranulation assay. An induction of Vδ2-cell differentiation, paralleled by increased cytotoxicity of both Vδ1 and Vδ2 cells against primary leukemia blasts was associated with ZOL treatment. Cytotoxic activity was further increased in Vδ2 cells, but not in Vδ1 lymphocytes in those patients given more than one treatment. Proteomic analysis of γδ T cells purified from patients showed upregulation of proteins involved in activation processes and immune response, paralleled by downregulation of proteins involved in proliferation. Moreover, a proteomic signature was identified for each ZOL treatment. Patients given three or more ZOL infusions had a better probability of survival in comparison to those given one or two treatments (86% vs. 54%, respectively, p = 0.008). Our data indicate that ZOL infusion in pediatric recipients of αβ T- and B-cell-depleted HLA-haploidentical HSCT promotes γδ T-cell differentiation and cytotoxicity and may influence the outcome of patients.

Background & Aim Leukemia is the most common cancer in childhood, accounting for almost 1 out of 3 cases. Of these malignancies, most are acute lymphoblastic leukemia (ALL), with the remaining cases largely acute myeloid leukemia (AML). Despite remarkable advances in treatments, 50%-70% of all children with ALL and AML who relapse after allogeneic hematopoietic stem cell transplantation (HSCT), succumb to their disease. Thus, there is an urgent clinical need of novel therapies for improving prognosis. γδ T cells are a minor subset (1-5%) of CD3+ combining conventional adaptive features with rapid, innate-like responses that place them in the initiation phase of immune cascade. In addition, they recognize tumor cells in a major histocompatibility complex (MHC) independent manner, thereby bypassing the occurrence of Graft versus Host Disease (GvHD). gd T cells is mainly constituted of Vg9Vd2 and Vd1 subpopulations which has demonstrated a potent Graft versus Leukemia (GvL) effect. The Vg9Vd2 subset, which represents the main circulating proportion of gd T cells, recognizes phospoantigens presented by leukemic blasts. The Vd1 subset, conversely, residing within the epithelial tissues, especially at sites of cytomegalovirus (CMV) replication, exerts a protective anti-infections post-transplant role. Methods, Results & Conclusion Here we purpose to develop a novel strategy for ex vivo expanding both Vg9Vd2 and Vd1 gdT-cells in a clinical-scale fashion. The ultimate goal is to post-HSCT administer multiple infusions of expanded gd T cells in order to reduce the risk of leukemia recurrence. We have previously demonstrated that the in vitro exposure of gd T cells to zoledronic acid (ZOL) combined with IL-2, allows robust expansion and activation of the Vd2 subset alone. Herein, we developed a novel protocol for the expansion of both Vd1 and Vd2 by exploiting the mitogenic effect of Concanavalin-A (Con-A), together with ZOL and a cocktail of different cytokines (Table 1). Preliminary results obtained from 5 different healthy donors show that 1) we succeeded in expanding gd T cells up to 50 folds, 2) the use of Con-A is essential for the Vd1 subset expansion, 3) gd T cells ex vivo expanded acquire an effector memory phenotype (Fig 1) and are cytotoxic in vitro against pediatric acute leukemia cell lines. Therefore, these encouraging results lay the foundation for advancing the translational use of gd T cells.

Purpose: Interleukin (IL)-18 is an immune-enhancing cytokine, which induces IFN-γ production, T-helper 1 responses, and antitumor effects. In turn, IFN-γ stimulates IL-18–binding protein production, which blocks IL-18 activity. In view of the potential use of IL-18 in epithelial ovarian cancer (EOC) immunotherapy, here, we studied IL-18BP expression and its regulation by cytokines in EOC cells in vitro and in vivo. Experimental Design: Expression and production of IL-18BP in EOC cell lines, primary ovarian carcinomas, and the corresponding normal tissues, patients' serum, and ascites were investigated by immunochemistry, ELISA, screening of gene expression profiles, and reverse-transcription PCR. Results: Analysis of gene expression profiles revealed that IL18BP mRNA is increased in EOC tumors compared with normal ovary cells. Release of IL-18BP was detectable in EOC sera and to a greater extent in the ascites, indicating production at the tumor site. Indeed, immunochemical analyses on cells isolated from the ascites and on tumor sections indicated that IL-18BP is expressed in both tumor cells and tumor-associated leukocytes, which displayed a CD3−CD20−NKp46−CD13+CD14low phenotype. EOC cell lines do not constitutively express IL-18BP. However, its release is inducible both by IFN-γ stimulation in vitro and by xenotransplantation of EOC cells in immune-deficient mice, suggesting a role for the microenvironment. In vitro experiments and immunochemistry indicated that IL-27 is also involved in IL-18BP upregulation in EOC cell lines and primary cells through STAT1 activation. Together, these data indicate that IL-18BP, which is produced in EOC in response to microenvironmental factors, may inhibit endogenous or exogenous IL-18 activity. Clin Cancer Res; 19(17); 4611–20. ©2013 AACR.

IL-27 and TCRγδ+ T lymphocytes play critical roles in both innate and adaptive immune responses in health and disease, including infection and tumors. Although the activity of IL-27 is well characterized in different human immune cells, no information is available on the role of IL-27 in human TCRγδ+ T lymphocytes. Here, we provide the first evidence that TCRγδ+ T lymphocytes express both gp130 and WSX-1 chains of IL-27R, and that IL-27 may function in TCRγδ+ T cells by (i) inducing STAT1 and STAT3 phosphorylation, (ii) stimulating cytotoxicity against tumor cells through upregulation of cytotoxic granules production, (iii) reducing the release of Th2-related cytokines, such as IL-5 and IL-13, and inducing IFN-γ production, and (iv) upregulating the expression of CD62L. These results highlighted a novel immunoregulatory property of human IL-27 that may be relevant in the immune response against tumors. Our results may offer new perspectives for the development of future clinical trials using IL-27 and TCRγδ+ cells for cancer immunotherapy.

Review of data identifying IL-12 and IL-27 as potential therapeutic agents for pediatric AML by targeting leukemia initiating cells and/or blasts. AML is a hematologic malignancy that represents 15–20% of all childhood acute leukemias and is responsible for more than one-half of pediatric leukemic deaths. The bulk tumor is continuously regenerated and sustained by rare leukemic ICs that proliferate slowly, thus resulting refractory to chemotherapeutic agents targeting highly proliferating cells within the tumor. Therefore, a complete eradication of the bulk tumor may depend on efficacy of therapies that target IC. In spite of the improvements in the treatment of AML, the difficulty to eradicate completely the disease incites research for innovative therapeutic approaches. In this regard, the role of cytokines in the treatment of AML has been investigated for many years, and some of them have been tested in clinical trials as a result of their immunomodulatory properties. Furthermore, recent preclinical studies highlighted the ability of the IL-12 superfamily cytokines as potent antileukemic agents that act directly on tumor cells and on leukemic IC, thus opening new perspectives for leukemic patient treatment. Here, we review the current knowledge about the antileukemic effects of cytokines, documented in preclinical and clinical studies, discussing their potential clinical application.

Interleukin (IL)-23 and IL-27 are pro-inflammatory cytokines that share functional and structural similarities and may exert anti-tumor activities against solid and hematological malignancies. Here, we asked whether IL-23 and IL-27, alone or in combination, may act directly against human follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) cells. In this study, we demonstrated for the first time that human primary FL and DLBCL cells expressed complete and functional IL-23 and IL-27 receptors (R) and that IL-23 and IL-27 exerted anti-tumor activities in vitro and in vivo through different and complementary mechanisms. In vivo studies using severe combined immunodeficiency /non-obese diabetic mice-injected subcutaneously with human SU-DHL-4 cell line revealed that IL-23 inhibited directly tumor-cell proliferation, whereas IL-27 impaired the angiogenic program of lymphoma cells resulting in strong reduction of cell growth. In addition, combined treatment of IL-23 and IL-27 amplified the anti-tumor effects in vivo as compared with administration of each cytokine alone. These anti-tumor mechanisms were confirmed by in vitro experiments performed with primary lymphoma cells and cell lines. Our results strongly encourage the development of future clinical trials to evaluate the toxicity and efficacy of the IL-23 and IL-27 in lymphoma patients.

B-acute lymphoblastic leukemia (B-ALL) represents the most common pediatric hematological tumor that derives from the aberrant proliferation of early B lymphocytes in the bone marrow. Although most of the B-ALL children take advantage from current therapeutic protocols, some patients relapse and need alternative therapies. With this background, we investigated whether interleukin (IL)-27, an immunomodulatory cytokine with antitumor properties, may function as an antitumor agent against pediatric B-ALL cells. Here we show for the first time that pediatric B-ALL cells functional IL-27R and that IL-27 dampens directly tumor growth in vivo and in vitro through mechanisms elucidated in this study. The novelty of these results deals with the first demonstration that (1) B-ALL cells from pediatric patients injected intravenously (i.v.) into NOD/SCID/Il2rg(-/-) (NSG) mice gave rise to leukemic spreading that was severely hampered by IL-27; (2) IL-27-treated mice, compared with controls, showed significant reduction of putative B-ALL-initiating cells and blasts in the peripheral blood (PB), bone marrow (BM) and spleen; and that (3) IL-27 reduced in vitro B-ALL cell proliferation and angiogenesis, induced apoptosis and downregulated miR-155. Our results strongly encourage the development of future clinical trials to evaluate the toxicity and efficacy of IL-27 in childhood B-ALL patients.

B-acute lymphoblastic leukemia (ALL) is the most common hematologic tumor of pediatric age. Although patient survival has been improved, some cases still relapse and need alternative therapies. In this context, the role of microRNA in cancer is actually matter of investigation due to their regulatory function implicated in human tumorigenesis since the main target mRNA transcripts are involved in proliferation, apoptosis and differentiation. On the other hand, cytokines are actually used as adjuvants in B-ALL therapy, and recent studies reported that they may also function by acting directly against leukemic cells. Here we review the current knowledge about the role of miRNA and cytokines in B-ALL, highlighting the link between cytokine activity and miRNA expression. The translational relevance of these issues will be also discussed.

Interleukin (IL) -12 is a cytokine that has been extensively characterized for its immunoregulatory activities. IL-12 binds to a heterodimeric receptor composed of the β1 and β2 chains. In this review article, we discuss recent findings on the expression and function of IL-12 receptor (IL-12R) in malignant B cells frozen at various stages of differentiation and in their normal counterparts. These studies, together with others performed in Il12rb2 knockout mice, have established the concept that the IL-12Rβ2 gene is a gatekeeper from cancer. We will delineate three paradigms reflecting the differential expression of IL-12Rβ2 in different groups of malignant B cells and discuss the therapeutic perspectives stemming from these studies.

Metastatic melanoma is a poor prognosis skin cancer. Since conventional treatments including surgery and chemotherapy often fail, novel therapeutic strategies are needed. In particular, identification of melanoma associated antigen has fostered the progress of both active (vaccines) and adoptive immunotherapy. Some promising results have been obtained, but most melanoma patients are not yet cured possibly because of different immune-escape mechanisms operated by tumor cells. Several studies have addressed the use of interleukin (IL)-12 for melanoma therapy due to its immunoregulatory function and anti-tumor activity mediated by stimulation of T and NK effector cells. Unfortunately, IL-12 has shown considerable toxicity. We [1] have recently demonstrated that IL-12 exerts a direct anti-tumor activity on murine B16 melanoma cells expressing a functional IL-12 receptor (R). In our model low levels of endogenous IL-12 reduced proliferation, increased apoptosis, and defective microvessel formation of tumor cells. This review summarizes information about melanoma immunotherapy and highlights a novel mechanism of IL-12-mediated anti-tumor activity based upon the direct effect of the cytokine on IL-12R(+) tumor cells. In this view, new therapeutic approaches may be planned including: i) pre-screening of melanoma patients for IL-12Rbeta2 expression to identify potential responders, ii) administration of small and less frequent doses of IL-12 to avoid toxicity and iii) targeting of IL-12 to IL-12R(+) tumor cells, such as local administration in patients with skin tumors or injection of IL-12 fused to an antibody specific to tumor cells.

Up-regulation of some chemokine receptors on tumor cells is associated with increased metastatic potential. In this respect, limited information is available on chemokine receptor in human neuroblastoma (NB). Purpose of the study was to identify chemokines/chemokine receptors involved in bone marrow (BM) localization of metastatic NB cells in view of the development of targeted therapeutic strategies. CD45− metastatic NB cells were isolated from the BM of six patients by immunomagnetic bead manipulation. Some experiments were carried out using a panel of human neuroblastoma cell lines (GI-ME-N, GI-LI-N, LAN-5, HTLA-230, SH-SY-5Y and IMR-32). Immunophenotypic analyses were performed by flow cytometry. Cell migration assays were carried out using transwell systems. Calcium ion mobilization, chemokine receptor internalization and cell proliferation were investigated by flow cytometry. In all BM samples, CXCR5 was expressed by the majority of primary neuroblasts and mediated their chemotaxis in response to CXCL13. Primary metastatic NB cells from all BM samples expressed CXCR6, but were not attracted by soluble CXCL16. Studies performed with two CXCR6+ NB cell lines showed that the mechanism whereby neuroblasts did not migrate to CXCL16 was likely related to defective calcium ion mobilization. CXCR5 is the first chemokine receptor so far identified able to attract in vitro primary metastatic NB cells. CXCR6 may be involved in retention of metastatic neuroblasts in the BM through interaction with CXCL16 expressing stromal cells in the absence of signal transduction.

// Grazia Carbotti 1 , Gaia Barisione 1 , Irma Airoldi 2 , Delia Mezzanzanica 3 , Marina Bagnoli 3 , Simone Ferrero 4 , Andrea Petretto 5 , Marina Fabbi 1 and Silvano Ferrini 1 1 Department of Integrated Oncological Therapies, IRCCS AOU San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy 2 Laboratory of Oncology, Istituto Giannina Gaslini, Genoa, Italy 3 Department of Experimental Oncology and Molecular Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy 4 Department of Surgery, Unit of Obstetrics and Gynaecology, IRCCS AOU San Martino-IST Istituto Nazionale per la Ricerca sul Cancro, and DINOGMI, University of Genoa Genoa, Italy 5 Core Facilities, Istituto Giannina Gaslini, Genoa, Italy Correspondence to: Silvano Ferrini, email: // Marina Fabbi, email: // Keywords : IL-27, IDO, PD-L1, STAT, Immunology and Microbiology Section, Immune response, Immunity Received : July 08, 2015 Accepted : November 30, 2015 Published : December 09, 2015 Abstract IL-27 is a member of the IL-12 family that is produced by macrophages and dendritic cells. IL-27 inhibits the growth and invasiveness of different cancers and therefore represents a potential anti-tumor agent. By contrast, it may exert immune-regulatory properties in different biological systems. We reported that IL-27 induces the expression of the IL-18 inhibitor IL-18BP, in human Epithelial Ovarian Cancer (EOC) cells, thus potentially limiting the immune response. Here, we tested whether IL-27 may modulate other immune-regulatory molecules involved in EOC progression, including Indoleamine 2,3-dioxygenase (IDO) and Programmed Death-Ligand (PD-L)1. IDO and PD-L1 were not constitutively expressed by EOC cells in vitro , but IL-27 increased their expression through STAT1 and STAT3 tyrosine phosphorylation. Differently, cells isolated from EOC ascites showed constitutive activation of STAT1 and STAT3 and IDO expression. These findings, together with the expression of IL-27 in scattered leukocytes in EOC ascites and tissues, suggest a potential role of IL-27 in immune-regulatory networks of EOC. In addition, IL-27 induced IDO or PD-L1 expression in monocytes and in human PC3 prostate and A549 lung cancer cells. A current paradigm in tumor immunology is that tumor cells may escape from immune control due to “adaptive resistance” mediated by T cell-secreted IFN-γ, which induces PD-L1 and IDO expression in tumor cells. Our present data indicate that also IL-27 has similar activities and suggest that the therapeutic use of IL-27 as anti-cancer agent may have dual effects, in some tumors.

We prospectively assessed functional and phenotypic characteristics of γδ T lymphocytes up to 7 months after HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) depleted of αβ+ T cells and CD19+ B cells in 27 children with either malignant or nonmalignant disorders. We demonstrate that (1) γδ T cells are the predominant T-cell population in patients during the first weeks after transplantation, being mainly, albeit not only, derived from cells infused with the graft and expanding in vivo; (2) central-memory cells predominated very early posttransplantation for both Vδ1 and Vδ2 subsets; (3) Vδ1 cells are specifically expanded in patients experiencing cytomegalovirus reactivation and are more cytotoxic compared with those of children who did not experience reactivation; (4) these subsets display a cytotoxic phenotype and degranulate when challenged with primary acute myeloid and lymphoid leukemia blasts; and (5) Vδ2 cells are expanded in vitro after exposure to zoledronic acid (ZOL) and efficiently lyse primary lymphoid and myeloid blasts. This is the first detailed characterization of γδ T cells emerging in peripheral blood of children after CD19+ B-cell and αβ+ T-cell–depleted haplo-HSCT. Our results can be instrumental to the development of clinical trials using ZOL for improving γδ T-cell killing capacity against leukemia cells. This trial was registered at www.clinicaltrials.gov as #{"type":"clinical-trial","attrs":{"text":"NCT01810120","term_id":"NCT01810120"}}NCT01810120.

The interleukin-12 receptor beta2 (Il12rb2) gene is silenced in tumor cells from different human B-cell malignancies as opposed to their normal counterparts. It was hypothesized that this silencing allows neoplastic B cells to escape the control exerted by IL-12 on their growth. The aim of this study was to investigate whether targeted inactivation of the Il12rb2 gene in mice resulted into increased susceptibility to spontaneous tumor formation and immunopathology. Il12rb2 gene-deficient animals developed in the first year of life immune-complex mesangial glomerulonephritis with serum antinuclear antibodies. In older animals, multiorgan lymphoid infiltrates with features of vasculitis and Sjögren syndrome were detected in association with systemic B- and T-cell activation. In half of aged animals, lymph node plasmacytoma or lung carcinoma was observed. A mechanism for spontaneous development of autoimmune pathology and B-cell tumors is suggested by a strong IL-6 up-regulation detected in splenocytes and lymphoid infiltrates associated with oligoclonal B-cell expansion. The emergence of lung tumors may likely be attributed to an interferon-gamma (IFN-gamma) deficiency secondary to lack of IL-12 signaling. The development of autoimmunity, lymphoproliferation, and B-cell tumors in Il12rb2 knockout (KO) mice suggests that IL-12 functions physiologically to restrain aberrant B-cell activation.

Neuroblastoma (NB) is a neuroectodermal tumor that affects children in the first years of life. Half of NB cases present with metastatic disease at diagnosis and have a poor prognosis, in spite of the most advanced chemotherapeutic protocols combined with autologous hematopoietic stem cell transplantation. Among the new avenues for NB treatment that are being explored, immunotherapy has attracted much interest. Emphasis has been placed on monoclonal antibodies directed to tumor-associated antigens--in particular the disialoganglioside GD2--that have been tested in the clinical setting with promising results. In addition, stimulation of cell-mediated antitumor effector mechanisms have been attempted-for example, by recombinant interleukin (IL)-2 administration. Nonetheless, the issue of the immunogenicity of human NB cells has never been thoroughly addressed. Here we shall review the work carried out in our lab in recent years and show that NB cells express tumor-associated antigens, such as MAGE-3, but lack constitutive expression of costimulatory molecules and surface HLA class I and II molecules. As such, NB cells are likely to be ignored by the host T cell compartment, since expression of HLA and costimulatory molecules on antigen presenting cells are sine qua non conditions for efficient peptide presentation to T cells and for the subsequent activation and clonal expansion of the latter cells. Notably, in vitro experiments with NB cell lines demonstrated that surface HLA class I molecules and the CD40 costimulatory molecule were upregulated following cell incubation with recombinant interferon-gamma. Interaction of CD40 with recombinant CD40 ligand induced apoptosis of NB cells through a caspase 8-dependent mechanism. Collectively, these results indicate that the immunogenicity of human NB cells is very low but suggest that manipulation by cytokine administration or gene transfer can increase their immunogenic potential. On the other hand, NB cells represent an excellent target for natural killer cells, the potential role of which in immunotherapy of NB is now being investigated.

Purpose: Dysregulated cytokine/cytokine receptor expression may occur in B-cell lymphoproliferative disorders. Little information is available on interleukin-18 receptor (IL-18R) and IL-18 expression in normal and malignant B cells. Our purpose was to investigate this issue in human naive, germinal center (GC) and memory B cells, and in their neoplastic counterparts. Experimental Design: We have evaluated IL-18 expression and production in tonsil naive, GC, and memory B cells and in their presumed neoplastic counterparts by reverse transcription-PCR and ELISA. Moreover, IL-18Rα and β expression was investigated in the same cells by reverse transcription-PCR, flow cytometry, and immunohistochemistry. Results: We found that: (a) IL-18 mRNA was expressed in tonsil naive, GC, and memory B cells. Bioactive IL-18 was secreted by naive and GC, but not by memory B cells; (b) IL-18Rα and β transcripts were expressed in the three B-cell subsets. IL-18Rα was detected on the surface of naive, GC, and memory B lymphocytes, and IL-18Rβ was detected on GC and memory, but not naive, B cells; (c) mantle zone, follicular, marginal zone, Burkitt lymphoma (BL), and B-cell chronic lymphocytic leukemia (B-CLL) cells expressed IL-18 mRNA. B-CLL and BL cells did not produce bioactive IL-18; and (d) lymphoma B cells displayed heterogeneous expression of either or both IL-18R chain mRNA. In contrast, B-CLL cells expressed both IL-18R chains at the mRNA and protein levels. Conclusions: Dysregulated expression of IL-18 and/or IL-18R in chronic B-cell lymphoproliferative disorders may sometimes contribute to tumor escape from the host immune system.

Different cytokines play crucial roles in inflammation and in polarizing immune responses, including IL-27 that exerts pro- and anti-inflammatory functions. Although the activity of IL-27 is well characterized in murine immune cells, only limited information is available regarding the natural cellular sources of IL-27 in humans and its effects on human immune cells. Dendritic cells (DCs) are the most potent professional APCs that in the immature state are positioned throughout peripheral tissues by acting as sentinels, sensing the presence of Ags. Activated DCs migrate into the lymph nodes and direct Ag-specific T cell responses, thus acting as key players in both adaptive and innate immunity. In this study we asked whether IL-27 is produced by human secondary lymphoid organs and what is its functional role on human DCs. To our knowledge, we provide the first evidence that 1) in lymph nodes, macrophages are the major source for IL-27; 2) immature and mature human DCs express functional IL-27R; 3) IL-27 exerts immunosuppressive activity by crippling the Ag processing machinery in immature DCs under steady-state conditions and after pulsing with a viral Ag; and 4) IL-27 is chemotactic for human DCs. Our findings highlight novel mechanisms underlying the immunosuppressive activity of IL-27, suggesting that this cytokine may function as a homeostatic cytokine in secondary lymphoid organs by limiting duration and/or intensity of ongoing adaptive immune responses. The results presented in this study pave the way to future studies aimed at investigating whether dysregulation of IL-27 expression and function may be involved in pathogenesis of autoimmune disease and cancer.

HLA-G and HLA-E are HLA-Ib molecules with several immunoregulatory properties. Their cell surface expression can be modulated by different cytokines. Since IL-27 and IL-30 may either stimulate or regulate immune responses, we have here tested whether these cytokines may modulate HLA-G and -E expression and function on human monocytes. Monocytes expressed gp130 and WSX-1, the two chains of IL27 receptor (R), and IL6Rα(that serves as IL-30R, in combination with gp130). However, only IL27R appeared to be functional, as witnessed by IL-27 driven STAT1/ STAT3 phosphorylation. IL-27, but not IL-30, significantly upregulated HLA-E (but not HLA-G) expression on monocytes. IFN-γ; secretion by activated NK cells was dampened when the latter cells were cocultured with IL-27 pretreated autologous monocytes. Such effect was not achieved using untreated or IL-30 pretreated monocytes, thus indicating that IL-27 driven HLA-E upregulation might be involved, possibly through the interaction of this molecule with CD94/NKG2A inhibitory receptor on NK cells. In contrast, cytotoxic granules release by NK cell in response to K562 cells was unaffected in the presence of IL-27 pretreated monocytes. In conclusion, we delineated a novel immunoregulatory function of IL-27 involving HLA-E upregulation on monocytes that might in turn indirectly impair some NK cell functions.

A new method of graft manipulation based on physical removal of αβ+ T cells and CD19+ B cells, leaving mature NK cells and γδ T cells in the graft, has been recently developed for HLA-haploidentical HSCT. We demonstrated that γδ T cells collected from transplanted patients are endowed with capacity of killing leukemia cells after ex vivo treatment with zoledronic acid (ZOL). Thus, we hypothesized that infusion of ZOL in patients receiving this type of graft, may boost γδ T cell cytotoxic activity against leukemia cells. Thirty-three patients were treated with ZOL every 28 days at least twice. γδ T cells before and after ZOL treatments were studied till at least 7 months after HSCT by high-resolution mass spectrometry, flow-cytometry, and degranulation assay. Proteomic analysis of γd T cells purified from patients showed that, starting from the first infusion, ZOL caused up-regulation of proteins involved in activation processes and immune response, paralleled by down-regulation of proteins involved in proliferation. These findings are consistent with an induction of Vδ2 cell differentiation, paralleled by increased cytotoxicity of both Vδ1 and Vδ2 cells against primary leukemia blasts. Furthermore, a proteomic signature was identified for each individual ZOL treatment. Patients given 3 or more ZOL infusions had a better probability of survival in comparison to those given 1 or 2 treatments. In conclusion,ZOL influences Vδ2 cell activity, determines a specific proteomic signature and enhances anti-leukemia activity, this potentially resulting into an increased anti-tumor effect. Disclosures No relevant conflicts of interest to declare.

Previous studies have shown that the interleukin-12 receptor β2 (IL-12Rβ2) gene is expressed in normal naive, germinal center and memory B cells but not in their malignant counterparts. The aim of this study was to investigate (i) whether the IL-12Rβ2 gene is silenced in B-cell acute lymphoblastic leukemia (B-ALL) cells, and (ii) what the functional implications of such silencing for tumor growth are. Here, we show that although mature B cells expressed both chains of the IL-12R, normal pro-B and pre-B cells failed to express the IL-12Rβ2 chain. Similarly, primary tumor cells from pediatric pro-B, early pre-B, and pre-B ALL (30 cases) did not express the IL-12Rβ2 chain. IL-12Rβ2 gene silencing in B-ALL was found to depend on methylation of a CpG island in exon 1. Such methylation was not detected in normal early B cells that when differentiated into mature B cells expressed the IL-12Rβ2 gene. Detection of IL-12Rβ2 mRNA and protein in the tumorigenic 697 pre-B-ALL cell line allowed to perform functional experiments in severe combined immunodeficient/nonobese diabetic mice receiving 697 cells with or without human recombinant IL-12 (hrIL-12). hrIL-12 administration reduced tumor growth and metastasis through antiproliferative and proapoptotic rather than antiangiogenic, activities.In conclusion, epigenetic silencing of the IL-12Rβ2 gene represents a novel mechanism of tumor escape for B-ALL cells. (Cancer Res 2006; 66(8): 3978-80)

T-cell depleted HLA-haploidentical hematopoietic stem cell transplantation (HSCT) is a suitable option for patients in need of an allograft who lack a HLA-matched donor. Although it offers the advantage of being immediately applicable to virtually all patients, so far, graft manipulation with removal of all T lymphocyte subsets and of natural killer (NK) cells has been associated with an increased risk of life-threatening infections, as well as, in some studies, of leukemia recurrence. We recently developed a new method of graft manipulation based on the physical removal of αβ+ T cells and CD19+ B cells, which permits to leave mature NK cells and γδ+ T cells in the graft. We, thus, started a formal study (NCT01810120) in children with acute leukemia aimed at evaluating the safety and efficacy of this approach. As of April 2013, we enrolled 45 patients (pts; 29 males, 16 females). Median age at HSCT was 10.1 years (range 0.9-17.9). Thirty-five pts had acute lymphoblastic leukemia (ALL) and 10 acute myeloid leukemia (AML); all children were transplanted in morphological complete remission (CR). Fifteen pts were transplanted in first CR, 27 in second CR and 3 in more advanced CR. All pts transplanted in CR1 had either poor cytogenetic/molecular characteristics or high levels of minimal residual disease (MRD) at the end of induction therapy. The donor was either the mother (n=25) or the father (n=20); according to the model of KIR/KIR ligand disparity, 22 pts were transplanted from an NK-alloreactive donor. The median number of CD34+ cells, NK cells, γδ+ T cells, B cells and αβ+ T cells were 14.6, 31.7, 7.8, 0.08 and 0.04x106/kg, respectively. A myeloablative regimen, containing Total Body Irradiation in 34 cases, was given to all children, who also received anti-thymocyte globulin (12 mg/kg over 3 days, from -5 to -3). Rituximab (200 mg/m2) was administered on day -1 to further prevent EBV-related lymphoproliferative disorders. No pharmacological graft-versus-host disease (GVHD) prophylaxis was employed after transplantation. Sustained primary engraftment occurred in 44/45 pts, the remaining child being successfully re-transplanted from the other parent. The median time to reach an absolute neutrophil count >0.5x109/L and a platelet count >50x109/L was 13 days (9-18) and 11 days (8-20). No child developed gut or liver acute GVHD. Thirteen pts experienced skin-only grade I-II GVHD, this leading to a cumulative incidence (CI) of 29% (95% confidence interval, CO. IN., 18-45). Only 2 pts developed skin limited chronic GVHD. Two pts died for causes other than disease relapse (both in the first 60 days after HSCT), the CI of transplantation-related mortality (TRM) being 4% (CO. IN. 1-16). Seven pts relapsed, the CI of disease recurrence being 16% (CO. IN. 6-32). With a median follow-up of 11 months (range 2-30), the 2-year Kaplan Meier estimate of leukemia-free survival (LFS) was equal to 75% (CO. IN. 57-86); this value was 73% (CO. IN. 52-85) for pts with ALL. LFS of pts who did or did not experience skin-only acute GVHD was 83% (CO. IN. 48-96) and 72% (CO. IN. 50-86), p=NS. The probability of LFS of the 39 pts with either negative or low ( These data indicate that a selective graft manipulation results into effective prevention of both acute and chronic GVHD, rapid recovery of neutrophil and platelet counts and low TRM. Although the median observation time is still limited, also the CI of disease recurrence is encouraging. Post-transplant add-back of limited numbers of αβ+ T cells transduced with the iCasp9 suicide gene could optimize the recovery of this subset in early weeks after HSCT, maximizing immune-mediated viral and leukemia control, without an unacceptable risk of GVHD. Disclosures: No relevant conflicts of interest to declare.

Purpose: Acute myeloid leukemia (AML) accounts for more than half of fatal cases in all pediatric leukemia patients; this observation highlights the need of more effective therapies. Thus, we investigated whether interleukin (IL)-27, an immunomodulatory cytokine, functions as an antitumor agent against pediatric AML cells. Experimental Design: Expression of WSX-1 and gp130 on AML cells from 16 pediatric patients was studied by flow cytometry. Modulation of leukemia cell proliferation or apoptosis upon IL-27 treatment in vitro was tested by bromodeoxyuridine/propidium iodide (PI) and Ki67, or Annexin V/PI staining and flow cytometric analysis. The angiogenic potential of AML cells treated or not with IL-27 was studied by chorioallantoic membrane assay and PCR array. In vivo studies were carried out using nonobese diabetic/severe combined immunodeficient (NOD/SCID)/Il2rg−/− mice injected intravenously with five pediatric AML cell samples. Leukemic cells engrafted in PBS and IL-27–treated animals were studied by immunohistochemical/morphologic analysis and by PCR array for expression angiogenic/dissemination-related genes. Results: We provided the first demonstration that (i) AML cells injected into NOD/SCID/Il2rg−/− mice gave rise to leukemia dissemination that was severely hampered by IL-27, (ii) compared with controls, leukemia cells harvested from IL-27–treated mice showed significant reduction of their angiogenic and spreading related genes, and (iii) similarly to what was observed in vivo, IL-27 reduced in vitro AML cell proliferation and modulated the expression of different genes involved in the angiogenic/spreading process. Conclusion: These results provide an experimental rationale for the development of future clinical trials aimed at evaluating the toxicity and efficacy of IL-27. Clin Cancer Res; 18(6); 1630–40. ©2012 AACR.

Background: Immune recovery is crucial for patients treated with allogeneic HSCT and in particular of those receiving a T-cell depleted haplo-HSCT. We recently developed a novel method of graft manipulation based on physical elimination of α/β T cells and B-lymphocytes for preventing graft-versus-host disease (GvHD) and EBV-related lymphoproliferative disorders, respectively. Thanks to this approach, we successfully conducted a prospective trial in children with malignant or non-malignant disorders (ClinicalTrial.gov identifier: NCT01810120). Although patients enrolled in this trial had faster immune recovery and lower incidence of infections than those given haplo-HSCT after infusion of positively selected CD34+ cells, reconstitution of adaptive T-cell immunity remains suboptimal. We therefore designed a phase I/II trial aimed at testing the effect on post-transplant immune recovery of adoptive infusion (within 14 + 4 days after transplantation) of BPX-501 cells in children given haplo-HSCT after depletion of α/β T and B cells (ClinicalTrials.gov identifier: NCT02065869). Patients and methods: As of July 25th 2015, 23 children have been infused with BPX-501 cells. The 9 children included in the phase I portion of the study were given 2.5x105, 5x105, and 1x106 BPX-501 cells/kg, respectively, while the 14 included in the phase II received 1x106 BPX-501 cells/kg. This analysis refers to the 16 patients with a minimum follow-up of 90 days; 7 children had acute leukemia and 9 non-malignant disorders. Basic phenotype of circulating lymphocytes was assessed by flow cytometry on fresh heparinized peripheral blood samples at 10, 20, 30, 60, 90, 120 and 150 days post haplo-HSCT, respectively. The following antibodies were used: anti-TCRαβ FITC/anti-TCRγδ PE/anti-CD3 PerCP-Cy™5.5 (WT31, 11F2, SK7), anti-CD4 APC Cy7 (RPA-T4), anti-CD19 BV 510 (SJ25C1), anti-CD3 BV 421 (UCHT1), anti-CD56 PeCy7 (B159), anti-CD16 APC (B73.1), anti-CD8 APC (RPA-T8) from BD Biosciences (San Diego, CA, USA). Antigen-driven activation of peripheral mononuclear cells was evaluated by standard lymphoproliferation assay (LPA) with 3H-thymidine pulsing on day 4 and harvesting 18 hours later. Antigens included PHA or CMV, EBV and AdV whole viral lysate. Results were scored positive with stimulation indexes (SI) >10 for PHA and >3 for viral antigens. Results: None of the patients died from transplant-related complications. Chimerism analysis investigated through short tandem repeats showed that in all but 4 patients, cells were of donor origin before the infusion of BPX-501 cells. In the 4 patients, there was a reversion to complete donor chimerism after infusion of BPX-501 cells. At early time points after haplo-HSCT, gδ T cells predominated over αβ T lymphocytes; subsequently, this latter population became the more largely represented. The number of both CD3+ T lymphocytes and of BPX-501 cells is shown in Panel A of Figure 1, reconstitution of whole T cells in historical children given haplo-HSCT after depletion of α/β T cells is also shown. The number of CD3+ T lymphocytes reached greater than 0.5x109/L 2 months after infusion of BPX-501 cells. Remarkably, while usually immune recovery after transplantation is characterized by prevalence of CD8+ cells, in our patients the physiological predominance of CD4+ lymphocytes was maintained (Panel B of Figure 1. Reconstitution of natural killer cells (NK) is shown in Panel C of Figure 1. As compared to patients receiving CD34+ selected cell haplo-HSCT, children included in this study had a faster reconstitution of mature KIR+/NKG2A- NK cells. Serum levels of IgA and IgM over time are shown in Panel D of Figure 1: there was a recovery of newly synthetized Ig at 3 months. The analysis of the function of T cells showed that the proliferative response to a polyclonal mitogen or to CMV lysate was comparable to that of a healthy control in 50% of patients as early as day + 60 after haplo-HSCT and BPX-501; on day +150, all patients reached a normal SI. Response to both EBV and AdV antigens was slightly delayed, but progressively improved over time (see also Figure 2). Conclusions: Overall, these data indicate that infusion of BPX-501 cells is able to accelerate the recovery of adaptive T-cell immunity since these cells, once infused, expand in vivo and persist over time, potentially contributing to protect patients from infections. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Moseley: Bellicum Pharmaceuticals: Employment, Equity Ownership.

The immunomodulatory drugs (IMiDs®) exert an anti-myeloma effect by cereblon-dependent destruction of IKZF proteinseither through a direct action on multiple myeloma (MM) cells or through indirect immunomodulatory and anti-angiogenic effects.Previous data indicated that MM cells overexpress hypoxia inducible factor (HIF)-1α and that HIF-1α suppression significantly blocks MM-induced angiogenesis and reduces in vivo tumoral burden in MM mouse models. Interestingly, it has been recently reported that HIF-1α knock-down in MM cells potentiates the in vitro effect of Lenalidomide (LEN) on cell proliferation without changing cell viability and that LEN is not able to suppress HIF-1α expression in MM cells. These evidences give the rationale design to investigate the in vivo effect of HIF-1α stable suppression in MM cells on LEN sensitivity. Thus, in this study, we assessed the effect of LEN in vivo in combination with HIF-1α inhibition in a non-obese diabetic/severe combined immunodeficiency (NOD/SCID) subcutaneous mouse model using JJN3, a cell line known to be resistant to the cytotoxic effect of LEN. Different groups of animals were injected with JJN3-pLKO.1 (empty vector) or JJN3-anti-HIF1α, obtained by anti-HIF1α lentiviral shRNA pool. When tumors became palpable, mice were treated with LEN (5mg/kg), using the intraperitoneal route. After three weeks, we evaluated tumor volume and weight. Moreover, by immunohistochemistry on ex vivo plasmacytomas, we evaluated the expression of p27 and the microvascular density (MVD), checked by CD34 immunostaining. In addition, the expression of a p27 inhibitor, the S-phase kinase-associated protein 2 (SKP2), the expression of the HIF-1α target key mediator of glycolysis and tumoral growth, Hexokinase II (HK2), and the levels of pERK 1/2, and total Caspase-3 (Casp-3) were evaluated in the ex vivo plasmacytomas lysates by western blot. We found that LEN treatment induced a significant weight and volume reduction of the tumor burden in mice injected with JJN3 anti-HIF1α as compared to JJN3-pLKO.1. The p27 nuclear expression was significantly increased by LEN treatment in JJN3-anti-HIF1α as compared to JJN3 pLKO.1 mice and compared to JJN3-anti-HIF1α mice treated with vehicle. In addition, we demonstrated that LEN in combination with HIF-1α inhibition significantly reduced in vivo the expression of p-ERK1/2, total Casp-3, HK2 and the p27 inhibitor, SKP2. Because it is known that LEN exerts its anti-MM effect targeting the IKZF proteins, we further checked in vitro whether the effect of HIF-1α suppression and LEN treatment combination could be mediated by IKZF proteins modulation. Interestingly, after LEN (2-10µM) treatment we found that both IKZF1 and IKZF3 were not differentially expressed, whereas IRF4 was down regulated, in JJN3-anti-HIF1α as compared to JJN3 pLKO.1. Finally, regarding a possible combinatory effect on the in vivo angiogenesis, we found that both the number of CD34 positive vessels and the MVD were reduced in mice colonized by JJN3-anti-HIF1α as compared to JJN3-pLKO.1. On the other hand, LEN treatment did not further significantly reduce the number of CD34 positive vessels and the MVD. Accordingly, we did not find any significant inhibitory effect by LEN treatment on the main pro-angiogenic molecules in JJN3 anti-HIF1α as compared to JJN3 pLKO.1 even after 72 hours. Overall, our data indicate that HIF-1α suppression in MM cells significantly increases the anti-MM effect of LEN in vivo, mainly through the inhibition of proliferation signaling including the modulation of p27 pathway and the IKZF target protein IRF4, rather than to an anti-angiogenic effect. These data suggest that the combination of LEN and HIF-1α inhibition has a therapeutic rationale in MM. Disclosures No relevant conflicts of interest to declare.

Multiple myeloma is a monoclonal postgerminal center tumor that has phenotypic features of plasmablasts and/or plasma cells and usually localizes at multiple sites in the bone marrow. The pathogenesis of multiple myeloma is complex and dependent on the interactions between tumor cells and their microenvironment. Different cytokines, chemokines, and proangiogenic factors released in the tumor microenvironment are known to promote multiple myeloma cell growth. Here, we report recent advances on the role of 2 strictly related immunomodulatory cytokines, interleukin-27 (IL-27) and IL-23, in human normal and neoplastic plasma cells, highlighting their ability to (i) act directly against multiple myeloma cells, (ii) influence the multiple myeloma microenvironment by targeting osteoclast and osteoblast cells, and (iii) modulate normal plasma cell function. Finally, the therapeutic implication of these studies is discussed. Clin Cancer Res; 17(22); 6963–70. ©2011 AACR.

Chemokines have pleiotropic effects in regulating immunity, angiogenesis, and tumor growth. CXC and CC chemokine families members and their receptors are able to exert a proangiogenic or an antiangiogenic effect in experimental models and in human tumors. In this review article, we have summarized literature data and our studies concerning the angiostatic activity of chemokines. Their angiostatic activity may be a result of a direct effect on the biological functions of endothelial cells and/or an effect on tumor cells inhibiting their capability to stimulate new blood vessel formation. Moreover, chemokines have a pro- and antitumor effect within the tumor microenvironment by regulating immune cell infiltration and its antitumor activities. We have focused our interest on the role of IL-12 and IL-27 in solid and hematological tumors, and we have suggested and discussed their potential use as antiangiogenic agents in the treatment of such tumors.

This study tested the hypothesis that IL-27 and IL-23, two heterodimeric cytokines involved in physiological immune responses and immunological disorders, may function on human PC and plasmablasts. It was reported that IL-27 acts on human mature B cells, but the role of IL-27 and IL-23 in human PC remains to be established. Thus, we have asked whether these cytokines may modulate human PC functions using human PPC generated in vitro, PC isolated from tonsils, and BM. Here, we show for the first time that PC and PPC express complete IL-27R and that IL-27 exerts chemotactic properties on these cells and modulates different chemokines/chemokine receptors and secretion of IgM and IgG. Furthermore, we demonstrated that PC and PPC express both chains of IL-23R and IL-23 and exerted similar activity to IL-27 in terms of Ig production, while not inducing PC chemotaxis. These results may provide novel insight into the role of IL-27 and IL-23 in human B cell immune responses.

Interleukin (IL)–23 is a proinflammatory cytokine belonging to the IL-12 superfamily. The antitumor activity of IL-23 is controversial, and it is unknown whether or not the cytokine can act directly on tumor cells. The aim of this study was to investigate the potential direct antitumor activity of IL-23 in pediatric B-acute lymphoblastic leukemia (B-ALL) cells and to unravel the molecular mechanisms involved. Here, we show, for the first time, that IL-23R is up-regulated in primary B-ALL cells, compared with normal early B lymphocytes, and that IL-23 dampens directly tumor growth in vitro and in vivo through the inhibition of tumor cell proliferation and induction of apoptosis. The latter finding is related to IL-23–induced up-regulation of miR15a expression and the consequent down-regulation of BCL-2 protein expression in pediatric B-ALL cells. This study demonstrates that IL-23 possesses antileukemic activity and unravels the underlying mechanisms. Thus, IL-23 may be a candidate novel drug for the treatment of B-ALL patients unresponsive to current therapeutic standards.

Acute myeloid leukemia is a haematopoietic malignancy originating from the transformation of myeloid progenitors that proliferate and accumulate in the bone marrow. In AML patients the survival rate at 5 years is 40-50% highlighting the need for novel therapies. In this study we have asked whether IL-12, an immuno-modulatory cytokine with anti-tumor activity, may inhibit directly AML cell growth. We show that the human AML cell lines U937, K562 and THP-1 expressed both chains of the IL-12 receptor (R), i.e. IL-12Rβ1 and IL-12Rβ2. IL-12 inhibited the angiogenic potential of AML cells in vitro, but did not affect their survival or proliferation. In vivo experiments were performed using SCID-NOD mice injected intraperitoneally (i.p.) with the human U937 AML cell line and subsequently treated with human recombinant IL-12 or PBS i.p. Histological, immunohistochemical and flow cytometric analyses on explanted tumors revealed that IL-12 reduced new vessel formation, induced apoptosis and inhibited tumor cell proliferation. Studies on a panel of angiogenesis related genes in explanted tumors using PCR arrays showed significantly down-regulated expression of numerous pro-angiogenic genes including VEGF-C, IL-6, IL-8, CXCL1, CXCL6 and alanyl aminopeptidase in IL-12 vs PBS treated mice. This study shows for the first time that IL-12 targets directly AML cell growth and paves the way to further investigation of IL-12 as potential drug for AML treatment.

BACKGROUND: Non small cell lung cancer (NSCLC) is a leading cause of cancer death. We have shown previously that IL-12rb2 KO mice develop spontaneously lung adenocarcinomas or bronchioalveolar carcinomas. Aim of the study was to investigate i) IL-12Rbeta2 expression in human primary lung adenocarcinomas and in their counterparts, i.e. normal bronchial epithelial cells (NBEC), ii) the direct anti-tumor activity of IL-12 on lung adenocarcinoma cells in vitro and vivo, and the mechanisms involved, and iii) IL-12 activity on NBEC. METHODOLOGY/PRINCIPAL FINDINGS: Stage I lung adenocarcinomas showed significantly (P = 0.012) higher frequency of IL-12Rbeta2 expressing samples than stage II/III tumors. IL-12 treatment of IL-12R(+) neoplastic cells isolated from primary adenocarcinoma (n = 6) inhibited angiogenesis in vitro through down-regulation of different pro-angiogenic genes (e.g. IL-6, VEGF-C, VEGF-D, and laminin-5), as assessed by chorioallantoic membrane (CAM) assay and PCR array. In order to perform in vivo studies, the Calu6 NSCLC cell line was transfected with the IL-12RB2 containing plasmid (Calu6/beta2). Similar to that observed in primary tumors, IL-12 treatment of Calu6/beta2(+) cells inhibited angiogenesis in vitro. Tumors formed by Calu6/beta2 cells in SCID/NOD mice, inoculated subcutaneously or orthotopically, were significantly smaller following IL-12 vs PBS treatment due to inhibition of angiogenesis, and of IL-6 and VEGF-C production. Explanted tumors were studied by histology, immuno-histochemistry and PCR array. NBEC cells were isolated and cultured from lung specimens of non neoplastic origin. NBEC expressed IL-12R and released constitutively tumor promoting cytokines (e.g. IL-6 and CCL2). Treatment of NBEC with IL-12 down-regulated production of these cytokines. CONCLUSIONS: This study demonstrates that IL-12 inhibits directly the growth of human lung adenocarcinoma and targets the adjacent NBEC. These novel anti-tumor activities of IL-12 add to the well known immune-modulatory properties of the cytokine and may provide a rational basis for the development of a clinical trial.

The interleukin-12 (IL-12) receptor (R) B2 gene acts as tumor suppressor in human acute and chronic B-cell leukemias/lymphomas and IL-12rb2–deficient mice develop spontaneously localized plasmacytomas. With this background, we investigated the role of IL-12Rβ2 in multiple myeloma (MM) pathogenesis. Here we show the following: (1) IL-12Rβ2 was expressed in primary MM cells but down-regulated compared with normal polyclonal plasmablastic cells and plasma cells (PCs). IL-6 dampened IL-12Rβ2 expression on polyclonal plasmablastic cells and MM cells. (2) IL-12 reduced the proangiogenic activity of primary MM cells in vitro and decreased significantly (P = .001) the tumorigenicity of the NCI-H929 cell line in SCID/NOD mice by inhibiting cell proliferation and angiogenesis. The latter phenomenon was found to depend on abolished expression of a wide panel of proangiogenic genes and up-regulated expression of the antiangiogenic genes IFN-γ, IFN-α, platelet factor-4, and TIMP-2. Inhibition of the angiogenic potential of primary MM cells was related to down-regulated expression of the proangiogenic genes CCL11, vascular endothelial-cadherin, CD13, and AKT and to up-regulation of an IFN-γ–related antiangiogenic pathway. Thus, IL-12Rβ2 directly restrains MM cell growth, and targeting of IL-12 to tumor cells holds promise as new therapeutic strategy.

The IL12RB2 gene acts as a tumor suppressor in human B cell malignancies. Indeed, Il12rb2 knockout (KO) mice develop spontaneously B cell tumors, but also lung epithelial tumors. This latter phenotype may be related to (i) impairment of host IL-12-mediated immunosurveillance and/or (ii) IL-12 inability to inhibit directly the growth of IL-12 unresponsive malignant cells. To address this issue, we transplanted IL-12R+B16 melanoma cells into syngeneic Il12rb2 KO mice with the following rationale: (i) these mice have severe defects in IFN-γ production, as well as in cytotoxic T lymphocyte and natural killer cell cytotoxicity, and (ii) they produce but do not use IL-12 that can potentially bind to and target tumor cells only. Il12rb2 KO mice displayed higher endogenous serum levels of IL-12 and developed smaller B16 tumors than WT animals. These tumors showed reduced proliferation, increased apoptosis, and defective microvessel formation related to down-regulated expression of a set of proangiogenic genes previously unrelated to IL-12. Such effects depended on direct activity of endogenous IL-12 on tumor cells in KO mice, and hydrodynamic delivered IL-12 caused further reduced tumorigenicity of B16 cells in these mice. A previously undescribed mechanism of the IL-12 antitumor activity has been here identified and characterized.

Galectin-1 (Gal-1) is a lectin, involved in several processes related to cancer, including immunosuppression, angiogenesis, hypoxia, and metastases. However, the expression profiles of Gal-1 and its pathophysiological role in multiple myeloma (MM) cell growth, in the relationship between MM cells and the bone marrow (BM) microenvironment and in the MM-induced angiogenesis are unknown and were investigated in this study. Firstly we evaluatedGal-1 expression by CD138+ cells of a dataset of 133 MM patients at diagnosis (GSE16122) and 23 human myeloma cell lines (HMCLs) (GSE6205) or on a proprietary? dataset of primary mesenchymal stromal cells (MSCs) and osteoblasts (OBs) of 16 MM and 4 MGUS. CD138+ cells and HMCLs were positive for LGALS1 with no statistically significant differences. LGALS1 mRNA expression was positively correlated with 154 genes and negatively with 109 genes including ERG1 and SPARC. MSCs cells showed a higher expression of LGALS1 compared to the OBs and MM-OBs showed a higher expression of LGALS1 mRNA than that obtained from healthy subjects. Gene expression profiling (GEP) data were then validated by Real-Time PCR and western blot in freshly purified primary CD138+ and BM MSCs samples as well as in 6 HMCLs and in both human MSC (HS-5 and hMSC-Tert) and osteoblastic cell lines (HOBIT and HOB-01). Moreover, immunohistochemistry analyses on bone biopsies obtained from 12 MM, 9 smoldering MM, 9 MGUS and 3 plasma cell leukemia samples revealed an high level of Gal-1 protein expression by MM cells, OBs and vessels in all the patients tested. Secondly, we evaluated whether Gal-1 expression was regulated by hypoxia and by Hypoxia Inducible Factor-1a (HIF-1a) checking the effect of hypoxic treatment (1% of O2) and HIF-1α inhibition by shRNA lentivirus. We found that Gal-1 was upregulated in HMCLs upon hypoxic treatment and consistently the re-oxygenation process significantly restored the expression level of Gal-1. Interestingly the stable knock-down of HIF-1a significantly down-regulated Gal-1 expression in HMCLs both in normoxic and hypoxic conditions. Thereafter, we explored the effect of persistent Gal-1 inhibition in MM cells and BM microenvironment cells on cell proliferation, survival and the transcriptional and pro-angiogenic profiles. An anti-Gal-1 Lentivirus shRNA was used for Gal-1 stable knock-down in HMCLs (JJN3-anti-Gal-1 and OPM-2-anti-Gal-1) and MSC cell lines (HS-5 and HMSC-Tert) and the Scramble lentiviral vector (JJN3-Scramble and OPM-2-Scramble) was used as the empty control vector. The stable inhibition of Gal-1 did not affect the proliferation rate and viability of both HMCLs and MSC cell lines. On the other hand Gal-1 inhibition by shRNA lentivirus significantly modified the transcriptional profiles of HMCLs and HS-5, evaluated by U133 Plus2.0 Arrays (Affymetrix®) either in normoxic or hypoxic or re-oxygenation conditions. Among the genes significantly modulated by Gal-1 inhibition in HMCLs, we found that pro-angiogenic (eg. CCL2, MMP9) and adhesion molecules (eg. MCAM and STEAP1) were down-regulated by Gal-1 suppression in both normoxic and hypoxic conditions as well as some putative anti-tumoral genes, including EGR1, SPARC and TGFBI, and anti-angiogenic ones, including SEMA3A, were up-regulated by Gal-1 inhibition. In line with these observations, we found that Gal-1 suppression by shRNA significantly decreased the pro-angiogenic proprieties of HMCLs by an in vitro angiogenesis assay. Finally, we found that mice, injected subcutaneously with JJN3-anti-Gal-1 and OPM-2-anti-Gal-1, showed a reduction in the weight and volume of the tumor burden compared to mice inoculated with the JJN3-Scramble and OPM-2-Scramble. Moreover, a significant reduction in the number of CD34 positive vessels X field was observed. In an intratibial mouse model, JJN3-anti-Gal-1, JJN3-Scramble and JJN3 wild type were injected: in the anti-Gal-1 group tumors grew in reduced number and size compared to the Scramble group, moreover JJN3 anti-Gal-1 mice developed fewer and smaller lytic lesions on x-ray compared to the controls. Overall our data indicate that Gal-1 is highly expressed by MM cells and those of the BM microenvironment and that its expression is regulated by hypoxia. Gal-1 shows a role in MM-induced angiogenesis and its inhibition in MM cells significantly reduced tumor growth in vivo, suggesting that Gal-1 is a potential new therapeutic target in MM. Disclosures Giuliani: Celgene Italy: Research Funding.

Neuroblastoma (NB) is a common neuroectodermal tumor of childhood with low response to conventional therapy in patients with advanced stage disease. Among novel strategies, immumotherapy has attracted much interest. However, scanty information is available about the immunogenicity of human NB. Here, we review our data showing that human NB may evade the control mediated by T cytotoxic lymphocytes and natural killer (NK) cells through multiple mechanisms: (i) downregulation of HLA class I molecules and antigen processing machinery components (ii) downregulation of activating ligands for the activating immunoreceptor NKG2D expressed by cytotoxic T lymphocytes and NK cells. Additional mechanisms of immune evasion used by human NB cells are discussed.

IL-12 activates murine and human B cells, but little information is available as to the expression and function of IL-12R on human B lymphocytes. Here we show that the latter cells, freshly isolated from human tonsils, expressed the transcripts of both β1 and β2 chains of IL-12R and that β2 chain mRNA was selectively increased (4- to 5-fold) by incubation with Staphylococcus aureus Cowan I bacteria or IL-12. B cell stimulation with IL-12 induced de novo expression of the transcripts of the two chains of IL-18R, i.e., IL-1 receptor-related protein and accessory protein-like. Functional studies showed that both IL-12 and IL-18 signaled to B cells through the NF-κB pathway. In the case of IL-12, no involvement of STAT transcription factors, and in particular of STAT-4, was detected. c-rel and p50 were identified as the members of NF-κB family involved in IL-12-mediated signal transduction to B cells. IL-12 and IL-18 synergized in the induction of IFN-γ production by tonsillar B cells, but not in the stimulation of B cell differentiation, although either cytokine promoted IgM secretion in culture supernatants. Finally, naive but not germinal center or memory, tonsillar B cells were identified as the exclusive IL-12 targets in terms of induction of NF-κB activation and of IFN-γ production.

HLA-haploidentical hematopoietic stem cell transplantation (HSCT) using CD34+ selected cells is a widely used procedure, which, however, is complicated by delayed immune reconstitution. We recently developed a new method of graft manipulation based on the physical removal of αβ+ T cells and CD19+ B cells, which permits to leave mature natural killer (NK) cells and γδ+ T cells in the graft. These cells can exert a graft-versus-leukemia (GvL) effect and reduce the risk of infection. In particular, unconventional γδ T cells play a critical role in both innate and adaptive immunity and exert HLA-unrestricted cytotoxicity against both solid and hematological tumors, thus potentially acting as beneficial effector cells in transplanted patients. Moreover, such grafts may limit the risk of graft-versus-host disease and prevent EBV-related lymphoproliferative disease. We performed phenotypic and functional studies on γδ T cells collected from 20 pediatric patients (pts, 13 males, 7 females, median age 10 years, range 6 months to 16 years) that received this type of allograft. Eighteen pts had acute leukemia and 2 non-malignant disorders. Ex vivo assays of peripheral blood γδ T cell phenotype and function were performed weekly until Hospital discharge and monthly until 6 months after HSCT. Phenotype of γδ T cells was analysed by flow cytometry. Analyses were performed on mononuclear cells labelled with mAb panels (CD3, CD45, pan-γδ, anti-Vδ1, -Vδ2, -Vγ9, CD45RO, CD45RA, CD27, CD16, CD56) allowing the identification of the main γδ+ T cell subsets, including Vδ1+ and Vδ2+ cells, naïve, central memory (CM), effector memory (EM) and terminally differentiated (TD) γδ T cells. Functional studies were performed using γδ T cells shortly after collection from pts, as well as after in vitro expansion with zoledronic acid and IL-2 for 10 days. Cytotoxic activity of γδ T cells was tested against primary leukemia cells, through CD107a degranulation assay and/or standard 51Cr-release assay. In the first 4 weeks after HSCT, T cells were consistently of the γδ subset (>90% of CD45+CD3+ cells); by contrast, αβ+ T cells gradually increased over time. In approximately half of the pts, the percentage of αβ T cells exceeded that of γδ T cells already starting from 30 days after HSCT. γδ T cells consisted of Vδ2+Vγ9+ and Vδ1+Vγ9+/- cells, and marginally of the Vδ1-Vδ2-Vγ9- population. Detailed phenotypic characterization of Vδ1+ and Vδ2+ γδ T cells revealed that, at day +20 after HSCT, 44% of Vδ1+ cells were CM (identified as CD45RO+CD27+ cells), 26% naïve (CD45RO-CD27+), 21.4% TD (CD45RO-CD27-) and 6.1% EM (CD45RO+CD27-). Similarly, 55.4% of Vδ2+ γδ T lymphocytes were CM, 9.8% naïve, 11.4% TD and 23.1% EM. The proportion of the different Vδ2+ γδ T cell subset did not change significantly over time, especially when comparing that present at day +20 after HSCT (time point, TP1) with that measured 30 days after the attainment of a 1:1 ratio of αβ-to- γδ T cells (TP2) (Figure 1, left panel). By contrast, by comparing TP1 and TP2, we found that Vδ1+ CM γδ T cells decreased and EM cells increased over time, while naïve or TD Vδ1+ γδ T cells did not change (Figure 1, right panel). In transplanted pts experiencing cytomegalovirus (CMV) reactivation, γδ T cells mostly consisted of Vδ1+ cells (mean 59.8% of γδ T cells), among which 49% were TD, 22.7% EM, 18.9% CM and 10.1% naïve. Noteworthy, in transplanted pts who did not have CMV reactivation, the main γδ T cells showed a Vδ2+ phenotype. Functional studies revealed that pt-derived γδ T cells consistently expanded in vitro after exposure to zoledronic acid and IL-2, the resulting Vγ9Vδ2 population expressing mainly an EM phenotype. These Vγ9Vδ2 cells exerted cytotoxic activities against primary allogeneic leukemia cells, especially when leukemia cells were pre-treated with zoledronic acid (Figure 2). More importantly, both Vδ1+ and Vδ2+ γδ T cells obtained from transplanted pts showed cytotoxic activity against primary leukemia cells, as assessed by CD107a degranulation assay. In conclusion, we provide the first phenotypic and functional characterization of γδ T cells, analyzed over time in children transplanted with grafts depleted of αβ+ T cells and of B lymphocytes. Our results support the concept that γδ T cells are important effector cells, which can be expanded and activated after exposure to bisphosphonates and IL-2 with the aim of improving their killing capacity against leukemia cells. Disclosures: No relevant conflicts of interest to declare.

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.

Abstract 2947 It has been previously reported that bone marrow (BM) microenvironment is hypoxic in multiple myeloma (MM) patients and that hypoxia inducible factor (HIF)-1α is overexpressed by MM cells. However, the potential role of HIF-1α as a therapeutic target in MM is not known and is currently under investigation. In this study we explored the effect of persistent HIF-1α inhibition by expression of a lentivirus shRNA pool in MM cells on proliferation, survival and transcriptional and pro-angiogenic profiles of MM cells either in vitro or in vivo in mouse models. A HIF-1α Lentivirus shRNA pool was used for HIF-1α stable knock-down in human myeloma cell lines (HMCL)s and the pKLO.1 lentiviral vector was used as the empty control vector. HMCLs were infected and then selected with puromycin. Selected clones were screened for HIF-1α, HIF-1β, HIF-2α and HIF-3α. The transcriptional profiles were evaluated in the HMCL JJN3 cells transduced with shRNA forHIF-1α (JJN3-anti-HIF-1α) and on those infected with the control vector pKLO.1 (JJN3-pKLO.1) by U133 Plus2.0 Arrays (Affymetrix®) either in hypoxic or normoxic conditions. Microarray data were further validated by quantitative real time PCR and by ELISA assays for protein levels. Finally the effect of HIF-1α inhibition in MM cells was assessed in vivo in NOD/SCID mice both in subcutaneous and intratibial models. Together with tumor volume and weight, microvascular density was evaluated by CD34 immunostaining. Cortical bone thickness was determined by microQcT in the intratibial mouse model. Among the genes significantly modulated by HIF-1α inhibition (327 and 361 genes in hypoxic and normoxic condition, respectively), we found that the pro-angiogenic molecules VEGF, IL8, IL10, CCL2, CCL5, MMP9 were down-regulated by HIF-1α inhibition. Interestingly some pro-osteoclastogenic cytokines were also inhibited including IL-7 and CCL3/MIP-1α. In the in vivo mouse models, we found that mice, injected either subcutaneously or intratibially with JJN3-anti-HIF-1α, showed a dramatic reduction in the weight and volume of the tumor burden compared to mice inoculated with the JJN3-pKLO.1. A significant reduction in the number of vessels X field and VEGF immunostaining were observed in both mouse models. Moreover in the intratibial experiments HIF-1α inhibition significantly blocked MM-induced bone destruction. Overall our data indicate that HIF-1α suppression in myeloma cells significantly blocks MM-induced angiogenesis and reduces the MM tumor burden and bone destruction in vivo suggesting that HIF-1α is a potential therapeutic target in MM. Disclosures: No relevant conflicts of interest to declare.

Abstract 3927 Hypoxia-inducible factor (HIF)-1α is a critical trigger and regulator of tumor associated angiogenesis. It has been previously reported that bone marrow (BM) microenvironment is hypoxic in multiple myeloma (MM) patients and that HIF-1α is overexpressed by CD138+ MM cells and modulates the transcriptional and pro-angiogenic profiles of MM cells. The potential role of HIF-1α as a therapeutic target in MM is under investigation. To deepen this issue, in this study we explored the effect of a stable HIF-1α inhibition in MM cells on cell proliferation, survival and on MM-induced angiogenesis either in vitro or in vivo using a plasmocytoma model. Human myeloma cell lines (HMCL)s were screened for HIF-1α protein expression in normoxia condition finding that 2 out 5 HMCLs were positive (JJN3 and RPMI-8226). Anti-HIF-1α Lentivirus sh RNA pool was used for HIF-1α stable knock-out in human myeloma cell lines (HMCL)s whereas the pKLO.1 lentiviral vector was used as the empty control vector. HMCLs have been infected and selected with 0.4 ug/ml puromycin for 21 days and the selected clones screened for HIF-1α, HIF-1β, HIF-2α and HIF-3α. A selective inhibition on HIF-1α mRNA and protein expression was observed both in normoxic and hypoxic conditions. HMCLs proliferation and apoptosis were not affected by HIF-1α inhibition neither in hypoxia nor normoxia. Thereafter the transcriptional profiles on the HMCL JJN3 transduced with shRNA anti-HIF-1α (JJN3-anti-HIF-1α), as compared to those infected with the control vector pKLO.1 (JJN3-pKLO.1) have been analyzed by U133 Plus2.0 Arrays (Affymetrix ®) either in hypoxic or normoxic conditions. The raw intensity signals were extracted from CEL files and normalized using the RMA package for Bioconductor and custom GeneAnnot-based Chip Definition Files in R software. Absolute fold change higher than 1.5 was used to select differentially expressed genes. Among the genes significantly modulated (327 and 361 genes in hypoxic and normoxic condition, respectively) we found that the pro-angiogenic molecules VEGF, IL8, IL10, CCL2, CCL5, MMP9 were down-regulated in JJN3-anti-HIF-1α as compared to JJN3-pKLO.1 either in hypoxic or normoxic conditions. Microarray data were further validated by quantitative real time PCR. In line with this observation, we found that the pro-angiogenic properties of JJN3, evaluated by an in vitro angiogenesis assay (Angio-Kit, TCS), were significantly inhibited by the HIF-1α knock-out. Finally the potential involvement of HIF-1α in MM-induced angiogenesis was assessed in vivo in NOD/SCID mice in a subcutaneous model. We found that the mice which were injected subcutaneously with JJN3-anti-HIF-1α, showed a dramatic reduction of the weight and volume of the plasmocytoma mass than mice inoculated with the JJN3-pKLO.1 (P=0.0007 and P=0.012; respectively). Moreover we observed a significant reduction of the number of vessels X field stained by CD31 antigen (anti-HIF-1α vs. pKLO.1: −76%; P=0.003) and VEGF immunostaining, whereas the Ki67 index of the plasmocytoma mass only showed a slight reduction (anti-HIF-1α vs. pKLO.1: −14%, P=NS). Overall our data indicate that HIF-1α suppression in myeloma cells significantly blocks MM-induced angiogenic switch both in vitro and in vivo and consequently reduces the MM tumoral burden suggesting that HIF-1α is a potential therapeutic target in MM. Disclosures: Bolzoni: Celgene Italy: Research Funding. Giuliani:Celgene: Research Funding; Novartis: Research Funding.

Abstract 125 It is known that bone marrow (BM) angiogenesis is increased in multiple myeloma (MM) patients in relationship with disease progression and supports MM cell growth. MM-induced angiogenesis is mainly due to an overproduction of pro-angiogenic molecules by MM cells and the BM microenvironment. However, the molecular mechanisms at the basis of the angiogenic process are currently under investigation. The deregulation of the homeobox genes has been previously associated to tumor progression and neoangiogenesis. Particularly, overexpression of the homeobox HOXB7 is involved in tumor-associated angiogenic switch in solid tumors. Interestingly, we have recently shown that HOXB7 is one of the overexpressed genes in BM micorenvironment cells in MM patients as compared to healthy subjects. In this study we have investigated the expression of HOXB7 by MM cells and its potential role in MM-induced angiogenesis in vitro and in vivo. First, by microarray analysis we evaluated HOXB7 expression in MM cells finding that HOXB7 was overexpressed in 43% of 23 human myeloma cell lines (HMCLs) tested as compared to normal plasmacells. HOXB7 expression was further confirmed by real time PCR and western blot analysis. On the other hand a small fraction of patients (about 10% in a representative database of 133 MM patients) showed HOXB7 overexpression with a preferential distribution based on the characteristics of molecular MM subtypes being significantly overexpressed in those cases which did not show any of the primary IGH translocations, corresponding to the TC2 and TC3 groups in the translocations/cyclins (TC) classification. In order to investigate the potential role of HOXB7 in MM cells either we enforced HOXB7 expression by lentivirus vectors in JJN3 HMCL (JJN3-HOXB7) or we silenced its expression by appropriate siRNA in the KMS20 HMCL that constitutively over-expressed HOXB7. Interestingly we found that cell proliferation was significant higher in JJN3-HOXB7 as compared to JJN3 transduced with the empty vector (JJN3-pWPI) as well as HOXB7 downregulation in KMS20 significantly reduced their cell proliferation and viability. Following we evaluated the whole transcriptional and specifically the pro-angiogenic profile of JJN3-HOXB7 as compared to JJN3-pWPI using Genechips® HG-U133Plus 2.0 and an angiogenesis oligonucleotide arrays. We found that the pro-angiogenic cytokines as VEGFA, FGF2, MMP2 and PDGFA were significantly upregulated whereas we identified the specific downregulation of the angiogenic inhibitor TSP2 in JJN3-HOXB7. Data were then validated at protein level by ELISA assay in cell-conditioned media (CM). Consistently, we found that CM of JJN3-HOXB7 significantly stimulated vessel formation as compared to JJN3-pWPI using both in vitro angiogenic model (Angiokit) and chorioallantoic membrane assay. In line with these observations, we found that HOXB7 silencing by siRNA in KMS20 reduced the expression of pro-angiogenic molecules, including VEGF and FGF2, and growth factors. Finally the potential role of HOXB7 in MM-induced angiogenesis was tested in vivo in NOD/SCID mice. We found that mice injected with JJN3-HOXB7 cells developed a significantly bigger tumor mass than mice inoculated with the JJN3-pWPI (p=0.0039) with higher number of vessels stained by CD31 antigen. Moreover, the transcriptional and angiogenic profiles of the tumor mass indicated the upregulation of VEGFA, FGF2, MMP2, PDGFA and WNT5a as well as the downregulation of TSP2, at both mRNA and protein level in mice colonized by JJN3-HOXB7 as compared to those inoculated with JJN3-pWPI, confirming in vitro observations. In conclusion our data demonstrate the critical role of HOXB7 in the production of pro-angiogenic molecules by MM cells and in the regulation of MM-induced angiogenic switch suggesting that HOXB7 could be a potential therapeutic target in MM. Disclosures: No relevant conflicts of interest to declare.