Reciprocal changes in tumor antigenicity and antigen-specific T cell function during tumor progression

Therapeutic Approaches of Dual-targeted Nanomedicines for Tumor Multidrug Resistance

Currently, the main cause of cancer chemotherapy failure is multi-drug resistance (MDR), which involves a variety of complex mechanisms. Compared with traditional small-molecule chemotherapy, targeted nanomedicines offer promising alternative strategies as an emerging form of therapy, especially active targeted nanomedicines. However, although single-targeted nanomedicines have made some progress in tumor therapy, the complexity of tumor microenvironment and tumor heterogeneity limits their efficacy. Dual-targeted nanomedicines can simultaneously target two tumor-specific factors that cause tumor MDR, which have the potential in overcoming tumor MDR superior to single-targeted nanomedicines by further enhancing cell uptake and cytotoxicity in new forms, as well as the effectiveness of tumor-targeted delivery. This review discusses tumor MDR mechanisms and the latest achievements applied to dual-targeted nanomedicines in tumor MDR.

Intrinsic Immunogenic Tumor Cell Death Subtypes Delineate Prognosis and Responsiveness to Immunotherapy in Lung Adenocarcinoma

Recent studies have highlighted the combination of activation of host immunogenic cell death (ICD) and tumor-directed cytotoxic strategies. However, overall multiomic analysis of the intrinsic ICD property in lung adenocarcinoma (LUAD) has not been performed. Therefore, the aim of this study was to develop an ICD-based risk scoring system to predict overall survival (OS) and immunotherapeutic efficacy in patients. In our study, both weighted gene co-expression network analysis (WGCNA) and LASSO-Cox analysis were utilized to identify ICDrisk subtypes (ICDrisk). Moreover, we identify genomic alterations and differences in biological processes, analyze the immune microenvironment, and predict the response to immunotherapy in patients with pan-cancer. Importantly, immunogenicity subgroup typing was performed based on the immune score (IS) and microenvironmental tumor neoantigens (meTNAs). Our results demonstrate that ICDrisk subtypes were identified based on 16 genes. Furthermore, high ICDrisk was proved to be a poor prognostic factor in LUAD patients and indicated poor efficacy of immune checkpoint inhibitor (ICI) treatment in patients with pan-cancer. The two ICDrisk subtypes displayed distinct clinicopathologic features, tumor-infiltrating immune cell patterns, and biological processes. The IS^lowmeTNA^high subtype showed low intratumoral heterogeneity (ITH) and immune-activated phenotypes and correlated with better survival than the other subtypes within the high ICDrisk group. This study suggests effective biomarkers for the prediction of OS in LUAD patients and immunotherapeutic response across Pan-cancer and contributes to enhancing our understanding of intrinsic immunogenic tumor cell death.

A Winning New Combination? Toward Clinical Application in Oncology

Immunotherapy has substantial attention in oncology due to the success of CTLA-4 and PD-1 inhibitors in the treatment of melanoma, lung cancer, head and neck cancer, renal cell carcinoma, and Hodgkin's lymphoma. A deeper understanding of interaction of tumor with its environment and the immune system provides best guide for oncology research. Recent studies in oncology have explained how a tumor alters antigen presentation, avoids detection, and activation of the host immune system to live and develop. Understanding the connections between the tumor and the immune system has resulted in several innovative therapy options. The extensive field of gene therapy has provided a number of cutting-edge medicines that are expected to play an important role in lowering cancer-related mortality. This article explains the history, important breakthroughs, and future prospects for three separate gene therapy treatment modalities: immunotherapy, oncolytic virotherapy, and gene transfer. Immunotherapies have completely changed how cancer is treated, especially for individuals whose condition was previously thought to be incurable. Examples include ACT (adoptive cell therapy) and ICB (immune checkpoint blockade). This review article will discuss the relationship between the immune response to cancer and the mechanisms of immunotherapy resistance. It will cover combination drugs authorized by the US Food and Drug Administration and provide a thorough overview of how these drugs are doing clinically right now. Cytokines, vaccines, and other soluble immunoregulatory agents, innate immune modifiers, ACT, virotherapy, and other treatment modalities will all be covered in detail.

Anti-tumour effect of in situ vaccines combined with VEGFR inhibitors in the treatment of metastatic cervical cancer

Cervical cancer is the fourth most common malignant tumor in the world, for advanced cervical cancer, more than 30% of patients continue to have tumor and relapse or metastasis after the traditional treatment (concurrent chemoradiotherapy), and the response rate of immune checkpoint inhibitor (PD-1) is less 15%, so additional approaches are required. In situ vaccine is a very promising immunotherapy strategy. In the preclinical study, the combination of CPG and anti-Ox40 antibody can completely resolve injection site tumours and distant tumours and leads to the recovery of most mice with lymphoma. However, our early exploration process found that the effect of CpG + OX40 in the treatment of advanced cervical cancer is not ideal. Hence, we explored the anti-tumor effect of CpG + OX40 combined with anti-angiogenic therapy for the first time. The results showed that the combination significantly inhibited the proliferation of primary and secondary tumor volume and prolonged the survival time of mice, compared with the control group, CD3+, CD4 + and CD8 + T cells in the combined group showed an increasing trend. In addition, in terms of metabolism, the anti-vascular effect of anlotinib can significantly reduce the blood supply and metabolic level of tumor, the expression of Ki67 and CD31 in the control group was significantly higher than that in each administration group. In conclusion, our preclinical research results showed that the combination of in situ vaccine and anti-angiogenic therapy has a good anti-tumor effect, and may potentially offer an effective treatment option for patients with advanced cervical cancer.

Advances in pharmacotherapy for neuroblastoma

INTRODUCTION

Neuroblastoma is the most prevalent cancer type diagnosed within the first year after birth and accounts for 15% of deaths from pediatric cancer. Despite the improvements in survival rates of patients with neuroblastoma, the incidence of the disease has increased over the last decade. Neuroblastoma tumor cells harbor a vast range of variable and heterogeneous histochemical and genetic alterations which calls for the need to administer individualized and targeted therapies to induce tumor regression in each patient.

AREAS COVERED

This paper provides reviews the recent clinical trials which used chemotherapeutic and/or targeted agents as either monotherapies or in combination to improve the response rate in patients with neuroblastoma, and especially high-risk neuroblastoma. It also reviews some of the prominent preclinical studies which can provide the rationale for future clinical trials.

EXPERT OPINION

Although some distinguished advances in pharmacotherapy have been made to improve the survival rate and reduce adverse events in patients with neuroblastoma, a more comprehensive understanding of the mechanisms of tumorigenesis, resistance to therapies or relapse, identifying biomarkers of response to each specific drug, and developing predictive preclinical models of the tumor can lead to further breakthroughs in the treatment of neuroblastoma.

CMTM6 expression in M2 macrophages is a potential predictor of PD-1/PD-L1 inhibitor response in colorectal cancer

Background

CMTM6 is a novel key regulator of PD-L1. High expression of both CMTM6 and PD-L1 may predict the benefit of PD-1 axis blockade in lung cancer. We aimed to investigate the expression pattern of CMTM6 between mismatch repair-defective (dMMR) and mismatch repair-proficient (pMMR) colorectal cancer (CRC) tissues and assess its correlation with the response to PD-1/PD-L1 pathway blockade.

Methods

Immunohistochemistry (IHC) was used to analyze CMTM6 and PD-L1 expression and immune cell density in dMMR/pMMR CRC. Quantitative multiplex immunofluorescence (IF) was performed to detect CMTM6, PD-L1, CD4, CD8, CD68 and CD163 expression in CRC patients treated with PD-1/PD-L1 inhibitors.

Result

IHC analysis showed that CMTM6 and PD-L1 were both expressed in tumor cells (TCs) and invasion front immune cells (ICs). CMTM6 and PD-L1 expression and CD4⁺, CD8⁺, CD68⁺ or CD163⁺ cell density were significantly higher in dMMR CRC patients than in pMMR CRC patients. CMTM6 expression was positively correlated with PD-L1 expression and CD163⁺ M2 macrophage density in dMMR CRC. IF analysis showed that the coexpression rate of CMTM6/PD-L1 and the expression rate of CMTM6 in CD8⁺ T cells and CD163⁺ M2 macrophages were significantly increased in the group that exhibited clinical benefit. CMTM6 expression in M2 macrophages was identified as the best biomarker for predicting the responsiveness to PD-1/PD-L1 inhibitors.

Conclusions

CMTM6 expression in M2 macrophages may predict the PD-1/PD-L1 inhibitor response rate in CRC patients more accurately than dMMR/microsatellite instability-high (MSI-H) status. It can also identify pMMR CRC patients who could benefit from PD-1/PD-L1 inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-021-02931-6.

The intrinsic immunogenic properties of cancer cell lines, immunogenic cell death, and how these influence host antitumor immune responses

Modern cancer therapies often involve the combination of tumor-directed cytotoxic strategies and generation of a host antitumor immune response. The latter is unleashed by immunotherapies that activate the immune system generating a more immunostimulatory tumor microenvironment and a stronger tumor antigen-specific immune response. Studying the interaction between antitumor cytotoxic therapies, dying cancer cells, and the innate and adaptive immune system requires appropriate experimental tumor models in mice. In this review, we discuss the immunostimulatory and immunosuppressive properties of cancer cell lines commonly used in immunogenic cell death (ICD) studies being apoptosis or necroptosis. We will especially focus on the antigenic component of immunogenicity. While in several cancer cell lines the epitopes of endogenously expressed tumor antigens are known, these intrinsic epitopes are rarely determined in experimental apoptotic or necroptotic ICD settings. Instead by far the most ICD research studies investigate the antigenic response against exogenously expressed model antigens such as ovalbumin or retroviral epitopes (e.g., AH1). In this review, we will argue that the immune response against endogenous tumor antigens and the immunopeptidome profile of cancer cell lines affect the eventual biological readouts in the typical prophylactic tumor vaccination type of experiments used in ICD research, and we will propose additional methods involving immunopeptidome profiling, major histocompatibility complex molecule expression, and identification of tumor-infiltrating immune cells to document intrinsic immunogenicity following different cell death modalities.

The tumor-promoting effects of the adaptive immune system: a cause of hyperprogressive disease in cancer?

Adaptive antitumor immune responses, either cellular or humoral, aim at eliminating tumor cells expressing the cognate antigens. There are some instances, however, where these same immune responses have tumor-promoting effects. These effects can lead to the expansion of antigen-negative tumor cells, tumor cell proliferation and tumor growth, metastatic dissemination, resistance to antitumor therapy and apoptotic stimuli, acquisition of tumor-initiating potential and activation of various forms of survival mechanisms. We describe the basic mechanisms that underlie tumor-promoting adaptive immune responses and try to identify the variables that induce the switching of a tumor-inhibitory, cellular or humoral immune response, into a tumor-promoting one. We suggest that tumor-promoting adaptive immune responses may be at the origin of at least a fraction of hyperprogressive diseases (HPD) that are observed in cancer patients during therapy with immune checkpoint inhibitors (ICI) and, less frequently, with single-agent chemotherapy. We also propose the use of non-invasive biomarkers allowing to predict which patients may undergo HPD during ICI and other forms of antitumor therapy. Eventually, we suggest possibilities of therapeutic intervention allowing to inhibit tumor-promoting adaptive immune responses.

A review of fasting effects on the response of cancer to chemotherapy

BACKGROUND & AIMS

Studies suggest that fasting before or during chemotherapy may induce differential stress resistance, reducing the adverse effects of chemotherapy and enhancing the efficacy of drugs. In this article, we review the effects of fasting, including intermittent, periodic, water-only short-term fasting, and caloric restriction on the responsiveness of tumor cells to cytotoxic drugs, their protective effect on normal cells, and possible mechanisms of action.

METHODS

We could not perform a systematic review due to the wide variation in the study population, design, dependent measures, and outcomes (eg, type of cancer, treatment variation, experimental setting, etc.). However, a systematic approach to search and review literature was used. The electronic databases PubMed (MEDLINE), Scopus, and Embase were searched up to July 2020.

RESULTS

Fasting potentially improves the response of tumor cells to chemotherapy by (1) repairing DNA damage in normal tissues (but not tumor cells); (2) upregulating autophagy flux as a protection against damage to organelles and some cancer cells; (3) altering apoptosis and increasing tumor cells' sensitivity to the apoptotic stimuli, and preventing apoptosis-mediated damage to normal cells; (4) depleting regulatory T cells and improving the stimulation of CD8 cells; and (5) accumulating unfolded proteins and protecting cancer cells from immune surveillance. We also discuss how 'fasting-mimicking diet' as a modified form of fasting enables patients to eat a low calorie, low protein, and low sugar diet while achieving similar metabolic outcomes of fasting.

CONCLUSION

This review suggests the potential benefits of fasting in combination with chemotherapy to reduce tumor progression and increase the effectiveness of chemotherapy. However, with limited human trials, it is not possible to generalize the findings from animal and in vitro studies. More human studies with adequate sample size and follow-ups are required to confirm these findings.

Revisiting T Cell Tolerance as a Checkpoint Target for Cancer Immunotherapy

Immunotherapy has revolutionized the treatment of cancer. Nevertheless, the majority of patients do not respond to therapy, meaning a deeper understanding of tumor immune evasion strategies is required to boost treatment efficacy. The vast majority of immunotherapy studies have focused on how treatment reinvigorates exhausted CD8⁺ T cells within the tumor. In contrast, how therapies influence regulatory processes within the draining lymph node is less well studied. In particular, relatively little has been done to examine how tumors may exploit peripheral CD8⁺ T cell tolerance, an under-studied immune checkpoint that under normal circumstances prevents detrimental autoimmune disease by blocking the initiation of T cell responses. Here we review the therapeutic potential of blocking peripheral CD8⁺ T cell tolerance for the treatment of cancer. We first comprehensively review what has been learnt about the regulation of CD8⁺ T cell peripheral tolerance from the non-tumor models in which peripheral tolerance was first defined. We next consider how the tolerant state differs from other states of negative regulation, such as T cell exhaustion and senescence. Finally, we describe how tumors hijack the peripheral tolerance immune checkpoint to prevent anti-tumor immune responses, and argue that disruption of peripheral tolerance may contribute to both the anti-cancer efficacy and autoimmune side-effects of immunotherapy. Overall, we propose that a deeper understanding of peripheral tolerance will ultimately enable the development of more targeted and refined cancer immunotherapy approaches.

Enhancing anticancer activity of checkpoint immunotherapy by targeting RAS

Approximately 30% of human cancers harbor a gain‐in‐function mutation in the RAS gene, resulting in constitutive activation of the RAS protein to stimulate downstream signaling, including the RAS‐mitogen activated protein kinase pathway that drives cancer cells to proliferate and metastasize. RAS‐driven oncogenesis also promotes immune evasion by increasing the expression of programmed cell death ligand‐1, reducing the expression of major histocompatibility complex molecules that present antigens to T‐lymphocytes and altering the expression of cytokines that promote the differentiation and accumulation of immune suppressive cell types such as myeloid‐derived suppressor cells, regulatory T‐cells, and cancer‐associated fibroblasts. Together, these changes lead to an immune suppressive tumor microenvironment that impedes T‐cell activation and infiltration and promotes the outgrowth and metastasis of tumor cells. As a result, despite the growing success of checkpoint immunotherapy, many patients with RAS‐driven tumors experience resistance to therapy and poor clinical outcomes. Therefore, RAS inhibitors in development have the potential to weaken cancer cell immune evasion and enhance the antitumor immune response to improve survival of patients with RAS‐driven cancers. This review highlights the potential of RAS inhibitors to enhance or broaden the anticancer activity of currently available checkpoint immunotherapy.

Involvement of Heparanase in Gastric Cancer Progression and Immunotherapy

Heparanase is upregulated in various tumors, and its expression is closely associated with tumor growth, angiogenesis and metastasis, which accomplishes this mainly through degrading heparan sulfate and releasing heparin-binding growth factors thereby influencing multiple signaling pathways. In addition to its enzymatic degrading activity, heparanase can act via its non-enzymatic mechanisms that directly regulate various signaling. This review mainly focuses on the expression levels and role of heparanase in gastric cancer, and multiple genes and mechanisms regulating heparanase expression in gastric cancer. Furthermore, the development of heparanase-targeted immunotherapy and its potential application for treating gastric cancer are discussed.

Dominant role of the α-chain in rejection of tumor cells bearing a specific alloantigen in TCRα transgenic mice and in in vitro experiments

Both TCRα and TCRβ types of T-cell receptors contribute to antigen recognition. However, some TCRs have chain centricity, which means that either the α-chain or the β-chain dictates the peptide–MHC complex specificity. Most earlier reports investigated the role of well-studied β-chains in antigen recognition by TCRαβ. In a previous study, we identified TCRs specific to the H-2K^b molecule. In the present work, we generated transgenic mice carrying the α-chain of this TCR. We found that these transgenic mice rejected EL-4 tumor cells bearing alloantigen H-2K^b more effectively than wild-type mice and similarly to mice with established specific memory T cells. Moreover, we found that T cells transduced with this TCRα can inhibit EL-4 cell growth in vitro and in vivo. We also found that transgenic mice recruit fewer CD8 T cells into the peritoneal cavity at the peak of the immune response and had a significantly higher number of central memory CD8 T cells in the spleen of intact transgenic mice compared to intact wild-type control. These results indicate the ability of a single transgenic α-chain of the H-2K^b-specific TCR to determine specific recognition of the H-2K^b molecule by a repertoire of T lymphocytes and to rapidly reject H-2K^b-bearing lymphoma cells.

Tumor target amplification: Implications for nano drug delivery systems

Tumor cells overexpress surface markers which are absent from normal cells. These tumor-restricted antigenic signatures are a fundamental basis for distinguishing on-target from off-target cells for ligand-directed targeting of cancer cells. Unfortunately, tumor heterogeneity impedes the establishment of a solid expression pattern for a given target marker, leading to drastic changes in quality (availability) and quantity (number) of the target. Consequently, a subset of cancer cells remains untargeted during the course of treatment, which subsequently promotes drug-resistance and cancer relapse. Since target inefficiency is only problematic for cancer treatment and not for treatment of other pathological conditions such as viral/bacterial infections, target amplification or the generation of novel targets is key to providing eligible antigenic markers for effective targeted therapy. This review summarizes the limitations of current ligand-directed targeting strategies and provides a comprehensive overview of tumor target amplification strategies, including self-amplifying systems, dual targeting, artificial markers and peptide modification. We also discuss the therapeutic and diagnostic potential of these approaches, the underlying mechanism(s) and established methodologies, mostly in the context of different nanodelivery systems, to facilitate more effective ligand-directed cancer cell monitoring and targeting.

Resistance to anticancer immunity in cancer patients: potential strategies to reverse resistance

In the 1990s, the application of immunotherapy approaches to target cancer cells resulted in significant clinical responses in patients with advanced malignancies who were refractory to conventional therapies. While early immunotherapeutics were focused on T cell-mediated cytotoxic activity, subsequent efforts were centered on targeted antibody-mediated anticancer therapy. The initial success with antibody therapy encouraged further studies and, consequently, there are now more than 25 FDA-approved antibodies directed against a range of targets. Although both T cell and antibody therapies continue to result in significant clinical responses with minimal toxicity, a significant subset of patients does not respond to immunotherapy and another subset develops resistance following an initial response. This review is focused on describing examples showing that cancer resistance to immunotherapies indeed occurs. In addition, it reviews the mechanisms being used to overcome the resistance to immunotherapies by targeting the tumor cell directly and/or the tumor microenvironment.

Interferon-inducible CXC-chemokines are crucial immune modulators and survival predictors in colorectal cancer

Tumor-infiltrating T-cells are strongly associated with prognosis in colorectal cancer, but the mechanisms governing intratumoral lymphocyte recruitment are unclear. We investigated the clinical relevance and functional contribution of interferon-regulated CXC-chemokines CXCL9, CXCL10, and CXCL11, described as T-cells attractants. Their expression was significantly elevated in tumors as compared to normal colon in 163 patients with colon cancer, represented an independent positive predictor of post-operative survival, and was highly significantly correlated with the presence of tumor-infiltrating cytotoxic CD8⁺ T-cells and CD4⁺ T_H1-effector cells. The regulation of chemokine expression was investigated in established cell lines and in tissue explants from resected tumor specimen (n=22). All colorectal cancer cell lines tested, as well as stroma or endothelial cells, produced CXC-chemokines in response to cytokine stimulation. Moreover, resected tumor explants could be stimulated to produce CXC-chemokines, even in cases with initially low CXC-levels. Lastly, a causative role of chemokine expression was evaluated with an orthotopic mouse model, based on isogenic rectal CT26 cancer cells, engineered to express CXCL10. The orthotopic model demonstrated a protective and anti-metastatic role of intratumoral CXCL10 expression, mediated mainly by adaptive immunity.

Cytokines and metabolic factors regulate tumoricidal T-cell function during cancer immunotherapy

Recent advances in cancer biology and genetics have fostered precision therapies targeting tumor-specific attributes. Immune-based therapies that elicit cytolytic T cells (CTL) specific for tumor antigens can provide therapeutic benefit to cancer patients, however, cure rates are typically low. This largely results from immunosuppressive mechanisms operating within the tumor microenvironment, many of which inflict metabolic stresses upon CTL. Conversely, immunotherapies can mitigate specific metabolic stressors. For instance, dual costimulation immunotherapy with CD134 (OX40) plus CD137 (4-1BB) agonists appears to mediate tumor control in part by engaging cytokine networks that enable infiltrating CTL to compete for limiting supplies of glucose. Future efforts combining modalities that endow CTL with complimentary metabolic advantages should improve therapeutic efficacies.

Targeting Transcriptional Regulators of CD8+ T Cell Dysfunction to Boost Anti-Tumor Immunity

Transcription is a dynamic process influenced by the cellular environment: healthy, transformed, and otherwise. Genome-wide mRNA expression profiles reflect the collective impact of pathways modulating cell function under different conditions. In this review we focus on the transcriptional pathways that control tumor infiltrating CD8+ T cell (TIL) function. Simultaneous restraint of overlapping inhibitory pathways may confer TIL resistance to multiple mechanisms of suppression traditionally referred to as exhaustion, tolerance, or anergy. Although decades of work have laid a solid foundation of altered transcriptional networks underlying various subsets of hypofunctional or “dysfunctional” CD8+ T cells, an understanding of the relevance in TIL has just begun. With recent technological advances, it is now feasible to further elucidate and utilize these pathways in immunotherapy platforms that seek to increase TIL function.

Immunotherapeutic approaches for cancer therapy: An updated review

In spite of specific immune effector mechanisms raised against tumor cells, there are mechanisms employed by the tumor cells to keep them away from immune recognition and elimination; some of these mechanisms have been identified, while others are still poorly understood. Manipulation or augmentation of specific antitumor immune responses are now the preferred approaches for treatment of malignancies, and traditional therapeutic approaches are being replaced by the use of agents which potentiate immune effector mechanisms, broadly called "immunotherapy". Cancer immunotherapy is generally classified into two main classes including active and passive methods. Interventions to augment the immune system of the patient, for example, vaccination or adjuvant therapy, actively promote antitumor effector mechanisms to improve cancer elimination. On the other hand, administration of specific monoclonal antibodies (mAbs) against different tumor antigens and adoptive transfer of genetically-modified specific T cells are currently the most rapidly developing approaches for cancer targeted therapy. In this review, we will discuss the different modalities for active and passive immunotherapy for cancer.

Betting on improved cancer immunotherapy by doubling down on CD134 and CD137 co-stimulation

The ability of T cells to recognize a vast array of antigens enables them to destroy tumor cells while inflicting minimal collateral damage. Nevertheless, tumor antigens often are a form of self-antigen, and thus tumor immunity can be dampened by tolerance mechanisms that evolved to prevent autoimmunity. Since tolerance can be induced by steady-state antigen-presenting cells that provide insufficient co-stimulation, the exogenous administration of co-stimulatory agonists can favor the expansion and tumoricidal functions of tumor-specific T cells. Agonists of the co-stimulatory tumor necrosis factor receptor (TNFR) family members CD134 and CD137 exert antitumor activity in mice, and as monotherapies have exhibited encouraging results in clinical trials. This review focuses on how the dual administration of CD134 and CD137 agonists synergistically boosts T-cell priming and elaborates a multi-pronged antitumor immune response, as well as how such dual co-stimulation might be translated into effective anticancer therapies.

Inflammation programs self-reactive CD8+ T cells to acquire T-box-mediated effector function but does not prevent deletional tolerance

CD8(+) T cells must detect foreign antigens and differentiate into effector cells to eliminate infections. But, when self-antigen is recognized instead, mechanisms of peripheral tolerance prevent acquisition of effector function to avoid autoimmunity. These distinct responses are influenced by inflammatory and regulatory clues from the tissue environment, but the mechanism(s) by which naive T cells interpret these signals to generate the appropriate immune response are unclear. The identification of the molecules operative in these cell-fate decisions is crucial for developing new treatment options for patients with cancer or autoimmunity, where manipulation of T cell activity is desired to alter the course of disease. With the use of an in vivo murine model to examine CD8(+) T cell responses to healthy self-tissue, we correlated self-tolerance with a failure to induce the T-box transcription factors T-bet and Eomes. However, inflammation associated with acute microbial infection induced T-bet and Eomes expression and promoted effector differentiation of self-reactive T cells under conditions that normally favor tolerance. In the context of a Listeria infection, these functional responses relied on elevated T-bet expression, independent of Eomes. Alternatively, infection with LCMV induced higher Eomes expression, which was sufficient in the absence of T-bet to promote effector cytokine production. Our results place T-box transcription factors at a molecular crossroads between CD8(+) T cell anergy and effector function upon recognition of peripheral self-antigen, and suggest that inflammation during T cell priming directs these distinct cellular responses.

Cellular and molecular mechanisms in cancer immune escape: a comprehensive review

Immune escape is the final phase of cancer immunoediting process wherein cancer modulates our immune system to escape from being destroyed by it. Many cellular and molecular events govern the cancer's evasion of host immune response. The tumor undergoes continuous remodeling at the genetic, epigenetic and metabolic level to acquire resistance to apoptosis. At the same time, it effectively modifies all the components of the host's immunome so as to escape from its antitumor effects. Moreover, it induces accumulation of suppressive cells like Treg and myeloid derived suppressor cells and factors which also enable it to elude the immune system. Recent research in this area helps in defining the role of newer players like miRNAs and exosomes in immune escape. The immunotherapeutic approaches developed to target the escape phase appear quite promising; however, the quest for a perfect therapeutic agent that can achieve maximum cure with minimal toxicity continues.

Extracellular NM23 Signaling in Breast Cancer: Incommodus Verum

The notion that breast cancers can survive in an individual patient in a dormant state only to grow as metastatic disease in the future, is in our view incontrovertibly established. Convincing too is the evidence that surgery to remove the primary tumor often terminates dormancy resulting in accelerated relapses. Accepting that many deaths due to breast cancer might be averted were we to understand the cellular mechanisms underlying escape from dormancy, we have examined the extracellular signals produced by breast cancers derived from women with metastatic breast disease. In this perspective, we explore the role of extracellular nucleotide signaling that we have proposed constitutes a pathological axis from the transformed tumor cell to the endothelium in the service of intravasation, dissemination, extravasation and angiogenesis. A role for the dinucleotide kinase NM23/NDPK (nucleoside diphosphate kinase) secreted by breast tumor cells in the generation of signals that stimulate vascular leakiness, anti-thrombosis, endothelial migration and growth, constitutes a mechanistic basis for escape from latency and offers putative therapeutic targets for breast cancer management not previously appreciated.

Potent CD4+ T-cell epitope P30 enhances HER2/neu-engineered dendritic cell-induced immunity against Tg1-1 breast cancer in transgenic FVBneuN mice by enhanced CD4+ T-cell-stimulated CTL responses

One of the major obstacles in human epidermal growth factor receptor (HER)-2/neu-specific trastuzumab immunotherapy of HER2/neu-positive breast cancer is the development of trastuzumab resistance, warranting the search for other therapeutic strategies. Although dendritic cell (DC) vaccines have been extensively applied in clinical trials for cancer treatment, the vaccination efficacy is still limited, mostly because DC vaccines are not sufficient to break tumor-associated antigen-specific self-immune tolerance in cancer patients. P30 (FNNFTVSFWLRVPKVSASHLE) derived from tetanus toxin is a universally potent CD4(+) T helper epitope capable of enhancing CD8(+) cytotoxic T-lymphocyte (CTL) responses. In this study, we constructed two recombinant adenoviral vectors (AdVs), AdVOVA-P30 and AdVHER2/neu-P30, expressing ovalbumin (OVA)-P30 and HER2/neu-P30. In order to enhance DC vaccine efficacy, we transfected mouse bone marrow (BM)-derived DCs with AdVOVA-P30 and AdVHER2/neu-P30 to generate engineered DCOVA-P30 and DCHER2/neu-P30 vaccines, respectively. We, then, compared CD4(+) and CD8(+) T-cell responses and antitumor immunity derived from DCOVA-P30 and DCHER2/neu-P30 vaccination in wild-type C57BL/6 and transgenic FVBneuN mice, respectively. We demonstrate that engineered DCOVA-P30 vaccine stimulates more efficient CD4(+) and CD8(+) T-cell responses than DCOVA in C57BL/6 mice. Interestingly, the increased DCOVA-P30-induced CTL responses are mainly contributed by enhanced CD4(+) T-cell-stimulated CTL proliferation. We show that DCOVA-P30 vaccine also stimulates more efficient therapeutic immunity against OVA-expressing BL6-10OVA melanoma than DCOVA in C57BL/6 mice. In addition, we demonstrate that DCHER2/neu-P30 vaccine stimulates more efficient CD4(+) and CD8(+) T-cell responses and protective immunity against HER2/neu-expressing Tg1-1 breast cancer than DCHER2/neu in transgenic FVBneuN mice with HER2/neu-specific self-immune tolerance. Therefore, the engineered DCHER2/neu-P30 vaccine may provide a new immunotherapy alternative for women with HER2/neu(+) breast cancer, especially for trastuzumab-resistant HER2/neu(+) breast cancer patients.

The interplay between HPV and host immunity in head and neck squamous cell carcinoma

Persistent infection with human papillomavirus (HPV) type 16 is a major risk factor for the development of head and neck squamous cell carcinoma (HNSCC), in particular oropharyngeal squamous cell carcinoma (OPSCC). The oropharyngeal epithelium differs from the mucosal epithelium at other commonly HPV16-infected sites (i.e., cervix and anogenital region) in that it is juxtaposed with the underlying lymphatic tissue, serving a key immunologic function in the surveillance of inhaled and ingested pathogens. Therefore, the natural history of infection and immune response to HPV at this site may differ from that at other anatomic locations. This review summarizes the literature concerning the adaptive immune response against HPV in the context of HNSCC, with a focus on the T-cell response. Recent studies have shown that a broad repertoire of tumor-infiltrating HPV-specific T-cells are found in nearly all patients with HPV-positive tumors. A systemic response is found in only a proportion of these. Furthermore, the local response is more frequent in OPSCC patients than in cervical cancer patients and HPV-negative OPSCC patients. Despite this, tumor persistence may be facilitated by abnormalities in antigen processing, a skewed T-helper cell response, and an increased local prevalence of T-regulatory cells. Nonetheless, the immunologic profile of HPV-positive vs. HPV-negative HNSCC is associated with a significantly better outcome, and the HPV-specific immune response is suggested to play a role in the significantly better response to therapy of HPV-positive patients. Immunoprofiling may prove a valuable prognostic tool, and immunotherapy trials targeting HPV are underway, providing hope for decreasing treatment-related toxicity.

Depleting tumor-specific Tregs at a single site eradicates disseminated tumors

Activation of TLR9 by direct injection of unmethylated CpG nucleotides into a tumor can induce a therapeutic immune response; however, Tregs eventually inhibit the antitumor immune response and thereby limit the power of cancer immunotherapies. In tumor-bearing mice, we found that Tregs within the tumor preferentially express the cell surface markers CTLA-4 and OX40. We show that intratumoral coinjection of anti-CTLA-4 and anti-OX40 together with CpG depleted tumor-infiltrating Tregs. This in situ immunomodulation, which was performed with low doses of antibodies in a single tumor, generated a systemic antitumor immune response that eradicated disseminated disease in mice. Further, this treatment modality was effective against established CNS lymphoma with leptomeningeal metastases, sites that are usually considered to be tumor cell sanctuaries in the context of conventional systemic therapy. These results demonstrate that antitumor immune effectors elicited by local immunomodulation can eradicate tumor cells at distant sites. We propose that, rather than using mAbs to target cancer cells systemically, mAbs could be used to target the tumor infiltrative immune cells locally, thereby eliciting a systemic immune response.

Improving T cell responses to modified peptides in tumor vaccines

Immune recognition and elimination of cancerous cells is the primary goal of cancer immunotherapy. However, obstacles including immune tolerance and tumor-induced immunosuppression often limit beneficial immune responses. Vaccination is one proposed intervention that may help to overcome these issues and is an active area of study in cancer immunotherapy. Immunizing with tumor antigenic peptides is a promising, straight-forward vaccine strategy hypothesized to boost preexisting antitumor immunity. However, tumor antigens are often weak T cell agonists, attributable to several mechanisms, including immune self-tolerance and poor immunogenicity of self-derived tumor peptides. One strategy for overcoming these mechanisms is vaccination with mimotopes, or peptide mimics of tumor antigens, which alter the antigen presentation and/or T cell activation to increase the expansion of tumor-specific T cells. Evaluation of mimotope vaccine strategies has revealed that even subtle alterations in peptide sequence can dramatically alter antigen presentation and T cell receptor recognition. Most of this research has been performed using T cell clones, which may not be accurate representations of the naturally occurring antitumor response. The relationship between clones generated after mimotope vaccination and the polyclonal T cell repertoire is unclear. Our work with mimotopes in a mouse model of colon carcinoma has revealed important insights into these issues. We propose that the identification of mimotopes based on stimulation of the naturally responding T cell repertoire will dramatically improve the efficacy of mimotope vaccination.

Antigen loss and tumor-mediated immunosuppression facilitate tumor recurrence

EVALUATION OF: Jensen SM, Twitty CG, Maston LD et al. Increased frequency of suppressive regulatory T cells and T cell-mediated antigen loss results in murine melanoma recurrence. J. Immunol. 189(2), 767-776 (2012). While tumor immunotherapy has seen notable success in recent years, mechanisms that tumors utilize to escape immune responses have provided significant hurdles to maximal clinical benefit. Escape mechanisms such as antigen loss, decreased MHC expression, as well as tumor-mediated suppressive effects on antitumor immune responses, can cause the most potent antitumor immune response to be rendered powerless at the tumor site. In this study, the authors show that the adoptive transfer of tumor antigen-specific CD4(+) and CD8(+) T cells combined with tumor cell immunization can elicit regression of established subcutaneous tumors in lymphopenic, but not lymphoreplete, animals. However, using a suboptimal dose of transferred cells followed by vaccination, the authors identify the development of recurrent tumors with reduced antigen expression. These tumors could still be eradicated in similarly treated animals; however, they found that transferred CD4(+) T cells from animals with recurrent tumors acquired a suppressive phenotype. This work highlights the importance of understanding mechanisms of tumor escape, particularly underscoring the role of the tumor in modulating antigen-specific immune responses, and the critical importance of finding mechanisms to avoid the development of viable escape variants.

Stat3 inhibition augments the immunogenicity of B-cell lymphoma cells, leading to effective antitumor immunity

Mantle cell lymphoma (MCL) is an aggressive and incurable subtype of B-cell non-Hodgkin lymphomas. Although patients often respond initially to first-line treatment with chemotherapy plus monoclonal antibodies, relapse and decreased response to further lines of treatment eventually occurs. Harnessing the immune system to elicit its exquisite specificity and long-lasting protection might provide sustained MCL immunity that could potentially eradicate residual malignant cells responsible for disease relapse. Here, we show that genetic or pharmacologic disruption of Stat3 in malignant B cells augments their immunogenicity leading to better activation of antigen-specific CD4(+) T cells and restoration of responsiveness of tolerized T cells. In addition, treatment of MCL-bearing mice with a specific Stat3 inhibitor resulted in decreased Stat3 phosphorylation in malignant B cells and anti-lymphoma immunity in vivo. Our findings therefore indicate that Stat3 inhibition may represent a therapeutic strategy to overcome tolerance to tumor antigens and elicit a strong immunity against MCL and other B-cell malignancies.

Expression of tumour-specific antigens underlies cancer immunoediting

Cancer immunoediting is a process by which immune cells, particularly lymphocytes of the adaptive immune system, protect the host from the development of cancer and alter tumour progression by driving the outgrowth of tumour cells with decreased sensitivity to immune attack^1,2. Carcinogen-induced mouse models of cancer have shown that primary tumour susceptibility is enhanced in immune-compromised mice, while conversely, the capacity for such tumours to grow after transplantation into wild-type mice is reduced^2,3. However, many questions about the process of cancer immunoediting remain unanswered due, in part, to the known antigenic complexity and heterogeneity of carcinogen-induced tumours⁴. Here we have adapted a genetically engineered, autochthonous mouse model of sarcomagenesis to investigate the process of cancer immunoediting. This system allowed us to monitor the onset and growth of immunogenic and non-immunogenic tumours induced in situ that harbor identical genetic and histopathological characteristics. By comparing the development of such tumours in immune-competent mice to mice with broad immunodeficiency or specific antigenic tolerance, we show that recognition of tumour-specific antigens (TSAs) by lymphocytes is critical for immunoediting against sarcomas. Furthermore, primary sarcomas were edited to become less immunogenic through the selective outgrowth of cells that were able to escape T lymphocyte attack. Loss of tumour antigen expression or MHCI presentation was necessary and sufficient for this immunoediting process to occur. These results highlight the importance of TSA expression in immune surveillance, and potentially, immunotherapy.

Evaluation of current cancer immunotherapy: hemato-oncology

Hematologic malignancies were the first diseases in clinical oncology for which the potential of harnessing the immune system as targeted therapy was unequivocally demonstrated. Unfortunately, the use of this highly efficacious modality has been limited to only a subset of patients and diseases because of immune-mediated toxicities resulting from incomplete specificity, and disease-specific determinants of sensitivity versus resistance to immune effector mechanisms. Recent studies, however, have begun to elucidate the molecular basis of the observed clinical effects allowing the rational development of next generation of immunotherapeutic combinations. We discuss here cancer antigen targets in hematologic malignancies and the specific approaches to induce immunity being pursued, the importance of modulating the host immunoregulatory environment, and the special features of immunological monitoring in clinical investigation. The hematologic malignancies represent an ideal setting for the development of immunotherapy due to logistical, clinical monitoring, and disease biology factors and may represent an exemplar for immune-based treatment in other cancer types.

CD134 plus CD137 dual costimulation induces Eomesodermin in CD4 T cells to program cytotoxic Th1 differentiation

Cytotoxic CD4 Th1 cells are emerging as a therapeutically useful T cell lineage that can effectively target tumors, but until now the pathways that govern their differentiation have been poorly understood. We demonstrate that CD134 (OX40) costimulation programs naive self- and virus-reactive CD4 T cells to undergo in vivo differentiation into cytotoxic Th1 effectors. CD137 (4-1BB) costimulation maximized clonal expansion, and IL-2 was necessary for cytotoxic Th1 differentiation. Importantly, the T-box transcription factor Eomesodermin was critical for inducing the cytotoxic marker granzyme B. CD134 plus CD137 dual costimulation also imprinted a cytotoxic phenotype on bystanding CD4 T cells. Thus, to our knowledge, the current study identifies for the first time a specific costimulatory pathway and an intracellular mechanism relying on Eomesodermin that induces both Ag-specific and bystander cytotoxic CD4 Th1 cells. This mechanism might be therapeutically useful because CD134 plus CD137 dual costimulation induced CD4 T cell-dependent tumoricidal function in a mouse melanoma model.

The ratio of intra-tumoral regulatory T cells (Foxp3+)/helper T cells (CD4+) is a prognostic factor and associated with recurrence pattern in gastric cardia cancer

BACKGROUND

TILs have been reported to be a prognostic factor in human cancers. We assessed the prognostic significance of tumor-infiltrating regulatory T cells in gastric cardia cancer.

METHODS

We retrospectively reviewed the database of Severance Hospital for patients who underwent curative resection of gastric cardia cancer from Jan 2000 to Dec 2006 and identified 180 patients. Immunohistochemistry for TIL subsets was performed against CD3, CD4, CD8, Foxp3, and granzyme B in the resected tumor specimens. The absolute numbers and relative ratios of positively stained lymphocytes for each subset were evaluated.

RESULTS

A high Foxp3/CD4 ratio was identified as an unfavorable prognostic factor for overall survival (OS) using univariate and multivariate analysis of all immunologic variables. Patients group with high Foxp3/CD4 ratio was associated with loco-regional recurrence (P = 0.033). In multivariate analysis for clinical and immunologic variables, the nodal status (hazards ratio--HR: 3.863, confidence interval--CI: 1.664-8.966, P = 0.002), depth of invasion (HR: 3.607, CI: 1.443-9.019, P = 0.006), and Foxp3/CD4 ratio (HR: 1.812, CI: 1.022-3.212, P = 0.042) were identified as independent prognostic factors for OS.

CONCLUSIONS

A higher regulatory T cells/helper T cells ratio is associated with an unfavorable prognosis and loco-regional recurrence pattern in gastric cardia cancer.

Bispecific antibodies engage T cells for antitumor immunotherapy

INTRODUCTION

Although considerable evidence supports the hypothesis that T cells play a critical role in the immune response against cancer, the ability to mount and sustain tumor-specific cellular responses in vivo remains a challenge. A strategy that harnesses the cytotoxic advantage of T cell therapy is the use of bispecific antibodies designed to engage and activate endogenous polyclonal T cell populations via the CD3 complex, but only in the presence of a tumor antigen. While antibody constructs with dual specificity were first described as anticancer therapeutics over 25 years ago, it was not until recently that one subclass of bispecific single-chain antibody, the bispecific T cell engager (BiTE), emerged as superior to previous iterations in achieving efficacy in animal models and early clinical trials.

AREAS COVERED

The evolution of bispecific antibodies in antitumor immunotherapy is reviewed and the greatest hurdles impeding their clinical translation are discussed, specifically in the context of immunoprivileged sites as is the case for intracerebral malignancy.

EXPERT OPINION

The BiTE platform has great potential in the treatment of malignant disease. Despite burgeoning interest in bispecific antibodies and permutations thereof, the issues of stability and cost-effective production persist as obstacles.

Heparanase: a universal immunotherapeutic target in human cancers

Heparanase has been identified as a particularly important player in metastasis, and its expression directly correlates with the metastatic spread of various tumors. Ideal targets for immunotherapy are gene products that are silenced in normal tissues but overexpressed in cancer, and that are directly involved in tumor cell survival and progression. Metastasis is the culmination of neoplastic progression. The importance of the role of heparanase in metastasis implies that immune escape by downregulation of heparanase expression could reduce the mortality of the cancer. These characteristics of heparanase make it an attractive universal target for cancer immunotherapy. Here, we review current knowledge about heparanase and its involvement in tumor metastasis, with an emphasis on recent results from heparanase-targeted cancer immunotherapy studies.

Epigenetic quantification of tumor-infiltrating T-lymphocytes

The immune system plays a pivotal role in tumor establishment. However, the role of T-lymphocytes within the tumor microenvironment as major cellular component of the adaptive effector immune response and their counterpart, regulatory T-cells (Treg), responsible for suppressive immune modulation, is not completely understood. This is partly due to the lack of reliable technical solutions for specific cell quantification in solid tissues. Previous reports indicated that epigenetic marks of immune cells, such as the Treg specifically demethylated region (TSDR) within the FOXP3 gene, may be exploited as robust analytical tool for Treg-quantification. Here, we expand the concept of epigenetic immunophenotyping to overall T-lymphocytes (oTL). This tool allows cell quantification with at least equivalent precision to FACS and is adoptable for analysis of blood and solid tissues. Based on this method, we analyse the frequency of Treg, oTL and their ratio in independent cohorts of healthy and tumorous ovarian, colorectal and bronchial tissues with 616 partly donor-matched samples. We find a shift of the median ratio of Treg-to-oTL from 3-8% in healthy tissue to 18-25% in all tumor entities. Epigenetically determined oTL frequencies correlate with the outcome of colorectal and ovarian cancers. Together, our data show that the composition of immune cells in tumor microenvironments can be quantitatively assessed by epigenetic measurements. This composition is disturbed in solid tumors, indicating a fundamental mechanism of tumor immune evasion. Epigenetic quantification of T-lymphocytes serves as independent clinical parameter for outcome prognosis.

Endogenous T cell responses to antigens expressed in lung adenocarcinomas delay malignant tumor progression

Neoantigens derived from somatic mutations in tumors may provide a critical link between the adaptive immune system and cancer. Here, we describe a system to introduce exogenous antigens into genetically engineered mouse lung cancers to mimic tumor neoantigens. We show that endogenous T cells respond to and infiltrate tumors, significantly delaying malignant progression. Despite continued antigen expression, T cell infiltration does not persist and tumors ultimately escape immune attack. Transplantation of cell lines derived from these lung tumors or prophylactic vaccination against the autochthonous tumors, however, results in rapid tumor eradication or selection of tumors that lose antigen expression. These results provide insight into the dynamic nature of the immune response to naturally arising tumors.

Direct CD4 help provision following interaction of memory CD4 and CD8 T cells with distinct antigen-presenting dendritic cells

Accumulating evidence suggests that CD4 help is needed at the memory stage to mount effective secondary CD8 T cell responses. In this paper, we report that memory CD4 T cells can provide efficient help to memory CD8 T cells after interaction of the two lymphocytes with distinct dendritic cells. Provision of help to CD8 T cells required direct cell-cell contact and involved both IL-2 and CD40 ligation, within a CD4-CD8 T cell synapse. Thus, following antigenic interaction with APCs, activated memory CD4 and CD8 T cells appear to separate from their respective APCs before meeting each other for help provision, regardless of their Ag specificity. CD4 help for memory CD8 T cells therefore appears to be conditioned primarily not by Ag specificity but by activation status.

Antigen presented by tumors in vivo determines the nature of CD8+ T-cell cytotoxicity

The biological relevance of the perforin and Fas ligand (FasL) cytolytic pathways of CD8(+) T lymphocytes (CTL) for cancer immunotherapy is controversial. We investigated the importance of these pathways in a murine renal cell carcinoma expressing influenza viral hemagglutinin as a defined surrogate antigen (Renca-HA). Following Renca-HA injection, all FasL-dysfunctional FasL(gld/gld) mice (n = 54) died from Renca-HA tumors by day 62. By contrast, perforin(-/-) (51%; n = 45) and Fas(lpr/lpr) (55%; n = 51) mice remained tumor-free at day 360. Blocking FasL in vivo inhibited tumor rejection in these mice. Moreover, established Renca-HA tumors were cleared more efficiently by adoptively transferred HA(518-526)-specific T-cell receptor-transgenic CTL using FasL rather than perforin. Strikingly, a range of mouse tumor cells presenting low concentrations of immunogenic peptide were all preferentially lysed by the FasL but not the Pfp-mediated effector pathway of CTL, whereas at higher peptide concentrations, the preference in effector pathway usage by CTL was lost. Interestingly, a number of human renal cancer lines were also susceptible to FasL-mediated cytotoxicity. Therefore, the FasL cytolytic pathway may be particularly important for eradicating Fas-sensitive tumors presenting low levels of MHC class I-associated antigens following adoptive T-cell therapy.

Toward development and production of human T cells in swine for potential use in adoptive T cell immunotherapy

Immunotherapy and vaccination for cancer or infection are generally approached by administration of antigen or stimulation of antigen-presenting cells or both. These measures may fail if the treated individual lacks T cells specific for the immunogen(s). We tested another strategy-the generation of new T cells from hematopoietic stem cells that might be used for adoptive immunotherapy. To test this concept, we introduced T cell-depleted human bone marrow cells into fetal swine and tested the swine for human T cells at various times after birth. Human T cells were detected in the thymus and blood of the treated swine. These cells were generated de novo as they contained human T cell receptor excision circles not present in the T cell-depleted bone marrow. The human T cells were highly diverse and included novel specificities capable of responding to antigen presented by human antigen-presenting cells. Our findings constitute a first step in a new promising approach to immunotherapy in which tumor- or virus-specific T cell clones lacking in an individual might be generated in a surrogate host from hematopoietic stem cells of the individual to be treated.

Immune manipulation of advanced breast cancer: an interpretative model of the relationship between immune system and tumor cell biology

This review summarizes some recent clinical immunological approaches with cytokines and/or antibodies for therapy of advanced breast cancer. It considers the recent advances in genetics and molecular tumor biology related to impaired immunosurveillance involving cytokines and growth factors to explain clinical results. Evasion of the host immune attack might be induced by the following groups of mechanisms: (a) tumor dependent (genomic instability, HLA class I antigen abnormalities, upregulation of fetal type nonclassical HLA class I molecules, epitope immunodominance, apoptosis inhibition by defective death receptor signaling, apoptosis of activated T cells, tumor cannibalism and constitutive activation of signal transducer, and activator of transcription-3 (Stat 3) and nuclear factor-kappaB (NF-kappaB) signaling); (b) host dependent (CD4+CD25+ regulatory T cells (T reg), CD4+ T cells anergy, Th2 antitumor immunity diversion and myeloid suppressor cells); (c) tumor and host dependent (lack of co-stimulation molecules, immunosuppressive cytokines (vascular endothelial growth factor (VEGF), interleukin (IL)-10, prostaglandin (PG)E2, transforming growth factor (TGF)-beta)). Cytokines and growth factors are involved in virtually all three types of mechanisms. These mechanisms are integrated with the current knowledge of tumor growth and inhibited apoptosis primarily mediated by cytokines and growth factors to propose an interpretation of the relationships among tumor cells, tumor stroma, and tumor-infiltrating lymphocytes. Tumor growth, defective immunorecognition and immunosuppression are the three principal effects considered responsible for immune evasion.

Termination of Systemic Immunity in the Presence of Intraocular Tumors: Influence of Ocular Immune Privilege on Tumor Vaccines

Ocular immune privilege preserves the visual axis by preventing the induction of sight-threatening nonspecific inflammation. Although privilege is essential for maintaining visual integrity, intraocular tumors exploit the privileged environment and grow progressively within the anterior chamber of the eye. Recently, a large number of laboratories have constructed genetically engineered tumor cell vaccines that express high levels of costimulatory signals. These vaccines are designed to bypass the normal pathways of T-cell activation and directly activate CD8+ tumor-specific T cells. In the following series of experiments, we determined whether a tumor cell vaccine that uses costimulatory signals (CD80 and IL-12) is capable of eliminating tumors within the immune-privileged anterior chamber. As expected, vaccine-immunized mice rejected subcutaneous flank tumors (a non-privileged site). However, the vaccine failed to protect mice from even a small number of tumor cells transplanted into the immune-privileged anterior chamber. Surprisingly, immunized mice that were simultaneously challenged with subcutaneous and anterior chamber tumors were unable to eliminate tumors at either site. The failure of systemic protective immunity coincided with the loss of tumor-specific delayed hypersensitivity and cytotoxic T cells. We conclude that tumor cell vaccines that induce complete protection against tumors in non-immune-privileged sites fail to protect against the same tumor within an ocular immune-privileged site. Moreover, a tumor that escapes elimination within the eye can terminate systemic protective immunity that is induced by the tumor cell vaccine.

Cellular immunotherapy for neuroblastoma: a review of current vaccine and adoptive T cell therapeutics

Immunotherapy is an attractive option for patients with high risk neuroblastoma due to their poor long-term survival rates after conventional treatment. Neuroblastoma cells are derived from the embryonic neural crest and therefore express tumor antigens not widely seen in normal cells, making them potential targets for immunologic attack. There is already considerable experience with monoclonal antibodies that target these tumor associated antigens, and in this review we focus on more exploratory approaches, using tumor vaccines and adoptive transfer of tumor-directed T cells.

Coordination of intratumoral immune reaction and human colorectal cancer recurrence

A role for the immune system in controlling the progression of solid tumors has been established in several mouse models. However, the effect of immune responses and tumor escape on patient prognosis in the context of human cancer is poorly understood. Here, we investigate the cellular and molecular parameters that could describe in situ immune responses in human colorectal cancer according to clinical parameters of metastatic lymph node or distant organ invasion (META- or META+ patients). Primary tumor samples of colorectal carcinoma were analyzed by integrating large-scale phenotypic (flow cytometry, 39 patients) and gene expression (real time reverse transcription-PCR, 103 patients) data sets related to immune and protumoral processes. In META- colorectal cancer primary tumors with high densities of T cells, we observed significant positive correlations between markers of innate immune cells [tumor-associated macrophages, dendritic cells, natural killer (NK) cells, and NKT cells] and markers of early-activated T cells. Significant correlations were also observed between markers of cytotoxic and effector memory T-cell subpopulations. These correlation profiles were absent in tumors with low T-cell infiltrates and were altered in META+ tumors with high T-cell infiltrates. We show that the coexpression of genes mediating cytotoxicity (GNLY) and Th1 adaptive immune responses (IRF1) accurately predicted patient survival independently of the metastatic status. High intratumoral mRNA expression of the proangiogenic mediator vascular endothelial growth factor was associated with significantly reduced survival rates in patients expressing high mRNA levels of GNLY. Investigation of the colorectal cancer primary tumor microenvironment allowed us to uncover the association of favorable outcomes with efficient coordination of the intratumoral immune response.

Heterospecific CD4 help to rescue CD8 T cell killers

Help from CD4 T cells may be required for optimal generation and maintenance of memory CD8 T cells and also for optimal Ag reactivation. We examined whether the helper cell and the CD8 killer cell need to have the same Ag specificity for help to be effective during interactions of memory T cells with mature APC. This is important because virus and tumor Ag-specific CD4 T cell responses are selectively impaired in several chronic viral infections and malignancies. We performed studies in vitro and in vivo and found that functional memory CD4 T cells generated from a distinct antigenic source (heterospecific helpers) could provide direct and effective help to memory CD8 T cells. Functional heterospecific memory CD4 T cells could also rescue secondary CD8 T cell responses in an experimental tumor model in which homospecific CD4 help was impaired. This could provide a rationale for immunotherapy strategies designed to bypass impaired homospecific help.

Whole-tumor-antigen-pulsed dendritic cells elicit cytotoxic T-cell response against pediatric nasopharyngeal carcinoma in vitro

Nasopharyngeal carcinoma (NPC) is endemic in Southeast Asia. Although dendritic cell (DC)-based vaccine has emerged as a promising immunotherapy for various malignancies, its use in pediatric nasopharyngeal carcinoma (PNPC) has not been addressed. In this study, DCs isolated from peripheral blood monocytes of three pediatric patients with advanced (stage IV) NPC were incubated with whole-tumor-antigen preparations and differentiated into immature DCs in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4, and then underwent maturation when exposed to tumor necrosis factor-alpha. Upon maturation, DCs acquired the ability to stimulate T-cell proliferation as examined by [(3)H]-thymidine incorporation and the ability of these T-cells to secrete interferon-gamma as determined by enzyme-linked immunosorbent spot assay. Cytotoxic assay revealed that mature tumor-antigen-pulsed DCs induced cytotoxic activity of the T-cells against both autologous and allogeneic NPC tumor cells (including NPC tumor cells from a different individual or from CNE-2Z, a poorly differentiated human NPC cell line). Blocking HLA class I molecules by W6/32 inhibited T-cell-mediated cytotoxic activity in both autologous and allogeneic settings. Our results indicate that DCs pulsed with whole-tumor-antigen can effectively activate HLA class I-restricted cytotoxic T-cells in vitro, and thus provide experimental basis for their future clinical use in PNPC.

Defective MHC class II presentation by dendritic cells limits CD4 T cell help for antitumor CD8 T cell responses

Cancer immunosurveillance failure is largely attributed to insufficient activation signals and dominant inhibitory stimuli for tumor Ag (TAg)-specific CD8 T cells. CD4 T cells have been shown to license dendritic cells (DC), thereby having the potential for converting CD8 T cell responses from tolerance to activation. To understand the potential cooperation of TAg-specific CD4 and CD8 T cells, we have characterized the responses of naive TCR transgenic CD8 and CD4 T cells to poorly immunogenic murine tumors. We found that whereas CD8 T cells sensed TAg and were tolerized, the CD4 T cells remained ignorant throughout tumor growth and did not provide help. This disparity in responses was due to normal TAg MHC class I cross-presentation by immature CD8alpha+ DC in the draining lymph node, but poor MHC class II presentation on all DC subsets due to selective inhibition by the tumor microenvironment. Thus, these results reveal a novel mechanism of cancer immunosubversion, in which inhibition of MHC-II TAg presentation on DC prevents CD4 T cell priming, thereby blocking any potential for licensing CD8alpha+ DC and helping tolerized CD8 T cells.