Klara Balint

Tumour hypoxia promotes tolerance and angiogenesis via CCL28 and T reg cells

Although immune mechanisms can suppress tumour growth, tumours establish potent, overlapping mechanisms that mediate immune evasion. Emerging evidence suggests a link between angiogenesis and the tolerance of tumours to immune mechanisms. Hypoxia, a condition that is known to drive angiogenesis in tumours, results in the release of damage-associated pattern molecules, which can trigger the rejection of tumours by the immune system. Thus, the counter-activation of tolerance mechanisms at the site of tumour hypoxia would be a crucial condition for maintaining the immunological escape of tumours. However, a direct link between tumour hypoxia and tolerance through the recruitment of regulatory cells has not been established. We proposed that tumour hypoxia induces the expression of chemotactic factors that promote tolerance. Here we show that tumour hypoxia promotes the recruitment of regulatory T (Treg) cells through induction of expression of the chemokine CC-chemokine ligand 28 (CCL28), which, in turn, promotes tumour tolerance and angiogenesis. Thus, peripheral immune tolerance and angiogenesis programs are closely connected and cooperate to sustain tumour growth.

Endothelin B receptor mediates the endothelial barrier to T cell homing to tumors and disables immune therapy.

In spite of their having sufficient immunogenicity, tumor vaccines remain largely ineffective. The mechanisms underlying this lack of efficacy are still unclear. Here we report a previously undescribed mechanism by which the tumor endothelium prevents T cell homing and hinders tumor immunotherapy. Transcriptional profiling of microdissected tumor endothelial cells from human ovarian cancers revealed genes associated with the absence or presence of tumor-infiltrating lymphocytes (TILs). Overexpression of the endothelin B receptor (ETBR) was associated with the absence of TILs and short patient survival time. The ETBR inhibitor BQ-788 increased T cell adhesion to human endothelium in vitro, an effect countered by intercellular adhesion molecule-1 (ICAM-1) blockade or treatment with NO donors. In mice, ETBR neutralization by BQ-788 increased T cell homing to tumors; this homing required ICAM-1 and enabled tumor response to otherwise ineffective immunotherapy in vivo without changes in systemic antitumor immune response. These findings highlight a molecular mechanism with the potential to be pharmacologically manipulated to enhance the efficacy of tumor immunotherapy in humans.

A Phase I vaccine trial using dendritic cells pulsed with autologous oxidized lysate for recurrent ovarian cancer

PurposeOvarian cancer, like most solid tumors, is in dire need of effective therapies. The significance of this trial lies in its promise to spearhead the development of combination immunotherapy and to introduce novel approaches to therapeutic immunomodulation, which could enable otherwise ineffective vaccines to achieve clinical efficacy.RationaleTumor-infiltrating T cells have been associated with improved outcome in ovarian cancer, suggesting that activation of antitumor immunity will improve survival. However, molecularly defined vaccines have been generally disappointing. Cancer vaccines elicit a modest frequency of low-to-moderate avidity tumor-specific T-cells, but powerful tumor barriers dampen the engraftment, expansion and function of these effector T-cells in the tumor, thus preventing them from reaching their full therapeutic potential. Our work has identified two important barriers in the tumor microenvironment: the blood-tumor barrier, which prevents homing of effector T cells, and T regulatory cells, which inactivate effector T cells. We hypothesize that cancer vaccine therapy will benefit from combinations that attenuate these two barrier mechanisms.DesignWe propose a three-cohort sequential study to investigate a combinatorial approach of a new dendritic cell (DC) vaccine pulsed with autologous whole tumor oxidized lysate, in combination with antiangiogenesis therapy (bevacizumab) and metronomic cyclophosphamide, which impacts Treg cells.InnovationThis study uses a novel autologous tumor vaccine developed with 4-day DCs pulsed with oxidized lysate to elicit antitumor response. Furthermore, the combination of bevacizumab with a whole tumor antigen vaccine has not been tested in the clinic. Finally the combination of bevacizumab and metronomic cyclophosphamide in immunotherapy is novel.

Immunotherapy for ovarian cancer: recent advances and perspectives.

Purpose of review Epithelial ovarian cancer is the most frequent cause of gynecologic cancer-related mortality in women, and prognosis for patients with recurrent or metastatic disease is extremely poor. Therefore, there is an enormous unmet need for the development of novel therapies in this indication. Although surgery and chemotherapy can improve survival rates, it is necessary to integrate alternative strategies, such as immunotherapy to improve the outcomes for patients with advanced ovarian cancer. Recent findings We will discuss the rationale of immunotherapy and some of the mechanisms of immunogenicity in ovarian cancer. We will highlight current results with cancer vaccines, adoptive T-cell therapy and immunomodulatory agents and will summarize the immune effects of selected chemotherapeutic agents, radiotherapy and recent results with combinatorial approaches in this disease setting. We will also discuss recent and potential future therapeutic interventions that might circumvent tumor-mediated immunosuppression. Summary Dramatic increase in the number of immunotherapy clinical trials was seen in the past decade with promising results in enhancing antitumor immune response and cancer vaccine efficacy. The future challenge for immunotherapy against ovarian cancer is to use a combinatorial approach to test rational, potentially synergistic immunotherapy combinations that can induce efficient antitumor immunity and prolong patients’ survival.

Local endothelial complement activation reverses endothelial quiescence, enabling t-cell homing, and tumor control during t-cell immunotherapy

ABSTRACT Cancer immunotherapy relies upon the ability of T cells to infiltrate tumors. The endothelium constitutes a barrier between the tumor and effector T cells, and the ability to manipulate local vascular permeability could be translated into effective immunotherapy. Here, we show that in the context of adoptive T cell therapy, antitumor T cells, delivered at high enough doses, can overcome the endothelial barrier and infiltrate tumors, a process that requires local production of C3, complement activation on tumor endothelium and release of C5a. C5a, in turn, acts on endothelial cells promoting the upregulation of adhesion molecules and T-cell homing. Genetic deletion of C3 or the C5a receptor 1 (C5aR1), and pharmacological blockade of C5aR1, impaired the ability of T cells to overcome the endothelial barrier, infiltrate tumors, and control tumor progression in vivo, while genetic chimera mice demonstrated that C3 and C5aR1 expression by tumor stroma, and not leukocytes, governs T cell homing, acting on the local endothelium. In vitro, endothelial C3 and C5a expressions were required for endothelial activation by type 1 cytokines. Our data indicate that effective immunotherapy is a consequence of successful homing of T cells in response to local complement activation, which disrupts the tumor endothelial barrier.

Potential approaches for more successful dendritic cell-based immunotherapy

Introduction: Dendritic cells (DCs) are the most important antigen-presenting cell population for activating antitumor T-cell responses; therefore, they offer a unique opportunity for specific targeting of tumors. Areas covered: We will discuss the critical factors for the enhancement of DC vaccine efficacy: different DC subsets, types of in vitro DC manufacturing protocol, types of tumor antigen to be loaded and finally different adjuvants for activating them. We will cover potential combinatorial strategies with immunomodulatory therapies: depleting T-regulatory (Treg) cells, blocking VEGF and blocking inhibitory signals. Furthermore, recommendations to incorporate these criteria into DC-based tumor immunotherapy will be suggested. Expert opinion: Monocyte-derived DCs are the most widely used DC subset in the clinic, whereas Langerhans cells and plasmacytoid DCs are two emerging DC subsets that are highly effective in eliciting cytotoxic T lymphocyte responses. Depending on the type of tumor antigens selected for loading DCs, it is important to optimize a protocol that will generate highly potent DCs. The future aim of DC-based immunotherapy is to combine it with one or more immunomodulatory therapies, for example, Treg cell depletion, VEGF blockage and T-cell checkpoint blockage, to elicit the most optimal antitumor immunity to induce long-term remission or even cure cancer patients.

Effect of Solar Particle Event Radiation on Gastrointestinal Tract Bacterial Translocation and Immune Activation

Space flight conditions within the protection of Earths gravitational field have been shown to alter immune responses, which could lead to potentially detrimental pathology. An additional risk of extended space travel outside the Earths gravitational field is the effect of solar particle event (SPE) radiation exposure on the immune system. Organisms that could lead to infection include endogenous, latent viruses, colonizing pathogenics, and commensals, as well as exogenous microbes present in the spacecraft or other astronauts. In this report, the effect of SPE-like radiation on containment of commensal bacteria and the innate immune response induced by its breakdown was investigated at the radiation energies, doses and dose rates expected during an extravehicular excursion outside the Earths gravitational field. A transient increase in serum lipopolysaccharide was observed 1 day after irradiation and was accompanied by an increase in acute-phase reactants and circulating proinflammatory cytokines, indicating immune activation. Baseline levels were reestablished by 5 days postirradiation. These findings suggest that astronauts exposed to SPE radiation could have impaired containment of colonizing bacteria and associated immune activation.

Ionizing Radiation Selectively Reduces Skin Regulatory T Cells and Alters Immune Function

The skin serves multiple functions that are critical for life. The protection from pathogens is achieved by a complicated interaction between aggressive effectors and controlling functions that limit damage. Inhomogeneous radiation with limited penetration is used in certain types of therapeutics and is experienced with exposure to solar particle events outside the protection of the Earth’s magnetic field. This study explores the effect of ionizing radiation on skin immune function. We demonstrate that radiation, both homogeneous and inhomogeneous, induces inflammation with resultant specific loss of regulatory T cells from the skin. This results in a hyper-responsive state with increased delayed type hypersensitivity in vivo and CD4+ T cell proliferation in vitro. The effects of inhomogeneous radiation to the skin of astronauts or as part of a therapeutic approach could result in an unexpected enhancement in skin immune function. The effects of this need to be considered in the design of radiation therapy protocols and in the development of countermeasures for extended space travel.

What Is the Future of Immunotherapy in Ovarian Cancer

Over the past several years, significant progress has been made in the treatment of gynecologic cancers. However, continued improvements to existing therapies, as well as development of novel approaches to treat these diseases, will be necessary to further reduce mortality. With increasing evidence that ovarian cancer in particular is immunogenic, there is a good reason to investigate the potential of immunotherapies. Recent success in a number of immunotherapy clinical trials targeting other tumor types has laid the groundwork necessary to begin using similar therapies against ovarian and other gynecologic cancers. Here we review past experience and future opportunities for immunotherapy in ovarian cancer, with a focus on vaccines and adoptive T-cell therapy, as well as several nonspecific immunomodulators available for immediate clinical testing.

Abstract 1421: Interleukin-22, a protective factor for ovarian cancer during TNFa-induced apoptosis.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Ovarian cancer is the 5th leading cause of death from cancer in women. Overall, only 10% of patients with advanced ovarian cancer are curable; despite the advances in chemotherapy the 5-year survival is still less than 30%. Interleukin-22 (IL-22), a member of the IL-10 family of cytokines is part of the innate immune system and is expressed by the Th17 cells. IL-22 has been shown to regulate several processes such as the acute-phase response, activation of the innate immune system, cell migration, differentiation and gene expression. However, its role in cancer immunology, especially in ovarian cancer has not been studied. The aim of this study is to investigate the expression and the role IL-22 in human ovarian cancer. In our work, we analyzed the expression of IL-22 protein in human ovarian cancer tissues and ascites samples using immunohistochemistry and ELISA; we tested the expression of IL-22 receptor on human ovarian cancer cells via Western Blot, and determined the association between disease outcome and IL-22 gene expression (Affymetrix)in patients with human ovarian cancer. We evaluated the effect of IL-22 on cellular proliferation using MTT assay and we assessed the effect of IL-22 on TNF-a induced apoptosis using caspase 3/7 activity (Caspase Glo) assay and 7AAD staining on multiple human ovarian cancer cell lines. Here we demonstrate that IL-22 was expressed in human ovarian cancer tissue (mostly in the stroma) and that the receptor for IL-22 was expressed on human ovarian cancer cells. We found that high expression of IL-22, as well as the IL-22-receptor in the tumor tissue leads to poor disease outcome in ovarian cancer patients. On the contrary, high expression of IL-22-binding protein (antagonist of IL-22) was associated with better survival in ovarian cancer patients. We showed that treatment with human recombinant (hr) IL-22 protein induced the activation of Stat-3, as well as increased the proliferation of human ovarian cancer cell lines. We also found that treatment with hr IL-22 at 100, 50 or even at 10 ng/mL concentrations inhibited TNF-a induced apoptosis in OVCAR-5 ovarian cancer cell line, and these results were reversed by the addition of IL22 binding protein to the culture. We conclude that interleukin-22 is an important factor in the tumor microenvironment of ovarian cancer; it promotes tumor growth by increasing proliferation and serves as a protective factor for ovarian cancer during TNF-s induced apoptosis. These data suggest that IL-22 is a potential therapeutical target and/or biomarker in human ovarian cancer. Citation Format: Klara Balint, Tamara Seedial, Phyllis Gimotty, George Coukos, Andrea Facciabene. Interleukin-22, a protective factor for ovarian cancer during TNFa-induced apoptosis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1421. doi:10.1158/1538-7445.AM2013-1421