Cancer Immunotherapy and Immunomonitoring (CITIM): Redefining Cancer Therapy

The immune system is a critical element involved in the control of tumor development and progression. While we have learned how to manipulate the immune system to generate tumor-specific immune responses, cancer immunotherapy has not yet delivered substantial clinical benefits. It has become increasingly clear that tumor-induced abnormalities in the immune system not only hamper natural tumor immune surveillance, but also limit the effect of cancer immunotherapy. If the results of recent studies are of any indication, then we are on the verge of a real breakthrough in our understanding of the immunobiology of tumor-host interactions and of ways to manipulate it. This 1^st International Conference on “Cancer Immunotherapy and Immunomonitoring (CITIM)” was the first meeting in Eastern Europe to specifically focus on the issue of immune regulation in the tumor environment, cancer immunotherapy, and immunomonitoring of immunotherapeutic clinical trials. This CITIM Conference held in Kiev, Ukraine, was comprised from eight plenary sessions and two special selected poster presentation sessions. Selected contributions from the participants of the Conference are presented in this issue of the Journal of Immunotoxicology.     

Immunotherapy of cancers comes of age

Introduction: Cancer immunotherapy has evolved and is aimed at generating the efficacious therapeutic modality to enhance the specificity and power of the immune system to combat tumors.

Areas covered: Current efforts in cancer immunotherapy fall into three main approaches. One approach is through the blockade of immune checkpoints, another approach is through adoptive cellular therapy, and the last approach is through vaccination. The goal of this review is to summarize the current understanding and status of cancer immunotherapy in these three categories.

Expert commentary: We foresee the development of therapeutic protocols combining these approaches with each other or conventional therapies to achieve the most appropriate guideline for management of cancer.     

Role of Gangliosides in Active Immunotherapy with Melanoma Vaccine

Among various tumor associated cell surface antigens, gangliosides, the glycosphingolipids that contain sialic acids, offer a variety of epitopes, some of which are preferentially expressed on melanoma cells. These surface components of the bilayered lipid membrane of tumor cells are the targets of active immunotherapy with melanoma vaccine. Purified gangliosides in aqueous solution form micelles and, at high density, form lactones. Their antigenic expression (physical conformation and orientation) on the cell surface is governed by the nature of the sphingosine and the fatty acids they contain. Evidence is accruing to show that the nature of the fatty acid moiety of gangliosides differs in normal and neoplastic cells. Gangliosides per se are not immunogenic and require extrinsic adjuvanticity. Preparation of a melanoma cell vaccine for active immunotherapy requires an understanding of the ganglioside profile of melanoma, the ganglioside-associated heterogeneity of melanoma, and the role of shed melanoma gangliosides in the immunosuppression of cell mediated and humoral immunity. In addition, the role of some of the anti-ganglioside antibodies in the elimination of shed gangliosides, the cytotoxic killing of tumor cells, as well as in the down-regulation of lymphocyte functions must be considered in the formulation of vaccine. Different strategies for augmenting the immunogenicity of melanoma associated gangliosides with melanoma vaccine are evaluated.     

Cancer vaccines: dream,reality, or nightmare?

Introduction. Over the past 30 years, a multidisciplinary approach com-bining surgery, chemotherapy, and radiation has led to a dramatic improvement in survival for patients affected by malignant diseases. Cellular therapies, such as stem cell transplantation, have also made a significant contribution. Nonetheless, many patients are still resistant to standard therapies, which also have high and often unacceptable acute and chronic organ toxicity, with an increased risk for secondary malignancies. Therefore new strategies are needed to improve overall survival and decrease treatment-asso-ciated morbidity. Immunotherapy represents one of the most appealing of these approaches, and active immunization in particular has proved to be amongst the most important of these new cellular strategies because of its ability to stimulate the immune system to actively recognize and kill the malignant cells. Identification of antigens expressed on tumor cells (Table 1), together with a better understanding of the molecular and cellular mechanisms involved in the immune response against cancer, have given investigators tools to manipulate the immune system to induce an efficient immune response in the tumor-bearing host [1-5]. The present review describes the approaches used in cancer vaccination that are intended not only to optimize antitu-mor immunity, but also to overcome tumor immune escape. Examples of how these approaches are being applied clinically are also given. Received: 9 September 2002 / Accepted: 23 September 2002 Correspondence to M. K. Brenner     

Cancer-Testis Antigens and Immunotherapy in the Light of Cancer Complexity

The ability of immunotherapy to evoke successful antitumor immune responses has been well documented over the past decade. Despite abundant preclinical data, it is only with the recent approval by the Food and Drug Administration (FDA) of the drugs such as sipuleucel-T and ipilimumab that immunotherapy is finally being recognized as a viable alternative to traditional therapies for treatment of various cancers. Despite the ability of immunotherapy to elicit successful antitumor immune responses, its efficacy is hindered by several factors. Among these are the paucity of tumor-associated antigens (TAA) that can be used as effective targets and the systemic toxicities that often lead to treatment interruption. Indeed, such adverse effects, which can be immunological and/or parenchymal, can be particularly severe and even fatal to some patients. A family of TAA called cancer-testis antigens (CTA) has been identified and their encoding genes have been extensively investigated. CTA expression has been demonstrated in a variety of human cancer tissues, and at least 19 CTA have been found to elicit humoral and/or cellular immune responses in cancer patients. Here we discuss how CTA and immunotherapy will most likely play a major role in the cure of cancer in the light of cancer complexity.     

Conference overview: Cancer Immunotherapy and Immunomonitoring (CITIM): Moving forward

The immune system is a critical element involved in the control of tumor development and progression. While professionals have learned how to manipulate the immune system to generate tumor-specific immune responses, cancer immunotherapy has not yet delivered substantial clinical benefits. It has become increasingly clear that tumor-induced abnormalities in the immune system not only hamper tumor immunosurveillance, but also limit the efficacy of cancer immunotherapy. Meanwhile, the results of recent studies allow the belief that one is on the edge of a real breakthrough in this promising direction in cancer therapy. The 2^nd International Conference ‘Cancer Immunotherapy and Immunomonitoring (CITIM)’ was the second meeting in Eastern Europe to specifically focus on the issue of immune regulation in the tumor environment, cancer immunotherapy, and immunomonitoring of immunotherapeutic clinical trials. This CITIM Conference held in Budapest, Hungary, was comprised from 12 plenary sessions, Best Abstract Award session, Poster session, and four Keynote lectures. Outstanding presentations and numerous productive discussions summarized the current place of the field and opened new directions for improving monitoring and therapy for patients with cancer.     

抗肿瘤血管生成主动免疫治疗研究进展

肿瘤血管生成在肿瘤生长、侵袭、转移中具有十分重要的作用。调控血管生成的因子很多,包括血管内皮细胞生长因子（VEGF）、成纤维细胞生长因子（FGF）、表皮细胞生长因子（EGF）等。近年来抗血管生成的肿瘤治疗已经取得较大进展,特别是抗肿瘤血管形成主动免疫治疗,已经成为抗肿瘤研究的热点。因而,以异种同源分子和非异种同源分子为疫苗的研究很有意义。     

Cancer immunotherapy: dawn of the death of cancer?

Abstract

Cancer is one of the proficient evaders of the immune system which claims millions of lives every year. Developing therapeutics against cancer is extremely challenging as cancer involves aberrations in self, most of which are not detected by the immune system. Conventional therapeutics like chemotherapy, radiotherapy are not only toxic but they significantly lower the quality of life. Immunotherapy, which gained momentum in the 20^th century, is emerging as one of the alternatives to the conventional therapies and is relatively less harmful but more costly. This review explores the modern advances in an array of such therapies and try to compare them along with a limited analysis of concerns associated with them.     

Targeting Costimulatory Pathways for Tumor Immunotherapy

Tumor immunotherapy harnesses the potential of the host immune system to recognize and eradicate neoplastic tissue. The efficiency of the immune system in mediating tumor regression depends on the induction of antigen-specific T-cell responses through physiologic immune surveillance, priming by vaccination, or following adoptive transfer of T-cells. Although a variety of tumor-associated antigens have been identified and many immunotherapeutic strategies have been tested, objective clinical responses are rare. The reasons for this include the inability of current immunotherapy approaches to generate efficient T-cell responses, the presence of regulatory cells that inhibit T-cell responses, and other tumor escape mechanisms. The activation of effector T-cells depends on interactions between the T-cell receptor (TCR) and cognate antigen presented as peptides within the major histocompatibility complex (MHC) and costimulatory signals delivered by CD28, which binds to B7.1 and B7.2. More recently, several new molecular receptors and ligands have been identified that integrate into stimulatory or inhibitory activity for T-cells. These signals have been loosely associated with the costimulatory molecules but actually represent a diverse group of molecular pathways that have unique and overlapping functions. This review will focus on these pathways and emphasize their role in mediating T-cell activation for the purpose of enhancing tumor immunotherapy. As we gain a better understanding of the molecular and cellular consequences of T-cell signaling through the costimulatory pathways, a more rational approach to the activation or inhibition of T-cell responses can be developed for the treatment of cancer and other immune-mediated diseases.     

Cancer/Testis Antigens: Expression,Regulation, Tumor Invasion,and Use in Immunotherapy of Cancers

Cancer/testis antigens (CTAs) are named based on their expression pattern that is restricted in a number of normal and abnormal tissues. Tumor cells frequently express antigens whose expression is typically restricted to germ cells. Their unique expression pattern is guaranteed by precise epigenetic regulatory mechanisms. Because of their tumor-limited, high immunogenicity, and biased expression, discovery of these molecules provides unprecedented opportunities for further research and clinical development in the field of cancer diagnosis and immunotherapy. Evolving evidence reveals that a number of CTAs stimulate epithelial mesenchymal transition (EMT) and generation of cancer stem-like cells, intensifying metastasis, invasion, and tumorigenesis. Based on these features, CTAs attract attention to be considered as ideal targets for developing several clinical trials, many of them concentrating on CTA vaccine therapy. According to recent practical clinical interest, more characterizations of CTA regulation are identified. CTA expression has been demonstrated in a variety of human cancer tissues, and some of them have been found to elicit humoral and/or cellular immune responses in cancer patients. CTAs are brilliant targets for anticancer drug discovery, targeted tumor therapy, and diagnostic biomarkers, furthermore, valued genes in the study of immunotherapy, promoting tumorigenesis, and malignant progression. This review outlines and categorizes our current understanding of the complex and biased process of CTAs mRNA and protein expression in cancer, and supplies the most recent information on their regulation and function. Besides, a concise synopsis of the major clinical trials involving CTAs, as therapeutic avenues, is discussed.

Abbreviations: AIRE: autoimmune regulator; cAMP: cyclic adenosine 3′,5′-cyclic monophosphate; CEA: carcinoembryonic antigen; CML: chronic myeloid leukemia; CREB: cyclicamp response element binding; CSCs: cancer stem cells; CTAs: cancer/testis antigens; CTL: cytotoxic T lymphocyte; DCs: dendritic cells; EMT: epithelial–mesenchymal transition; ERK: extracellular signal-regulated kinase; ESCC: esophageal squamous cell carcinoma; ETS: E26 transformation-specific; His: histidine; HLA: human leukocyte antigen; HNSCC: head and neck squamous cell carcinoma; IFN-γ: interferon-γ; IHC: Immunohistochemistry; IL-7: Interleukin7; MHC: major histocompatibility complex; MMP2: matrix metalloproteinase 2; mTECs: medullary thymus epithelial cells; MUC1: mucin 1; NSCLC: non-small cell lung cancer; PRAME: preferentially expressed antigen in melanoma; RDA: representational difference analysis; SEREX: serological analysis of cDNA expression; SSX: synovial sarcoma X chromosome; TAAs: tumor-associated antigens; TCR: T-cell receptor; TCGA: The Cancer Genome Atlas; TGF-β: transforming growth factor-β.     

Immunotherapy of Fungal Infections

Fungal organisms are ubiquitous in the environment. Pathogenic fungi, although relatively few in the whole gamut of microbial pathogens, are able to cause disease with varying degrees of severity in individuals with normal or impaired immunity. The disease state is an outcome of the fungal pathogen’s interactions with the host immunity, and therefore, it stands to reason that deep/invasive fungal diseases be amenable to immunotherapy. Therefore, antifungal immunotherapy continues to be attractive as an adjunct to the currently available antifungal chemotherapy options for a number of reasons, including the fact that existing antifungal drugs, albeit largely effective, are not without limitations, and that morbidity and mortality associated with invasive mycoses are still unacceptably high. For several decades, intense basic research efforts have been directed at development of fungal immunotherapies. Nevertheless, this approach suffers from a severe bench-bedside disconnect owing to several reasons: the chemical and biological peculiarities of the fungal antigens, the complexities of host-pathogen interactions, an under-appreciation of the fungal disease landscape, the requirement of considerable financial investment to bring these therapies to clinical use, as well as practical problems associated with immunizations. In this general, non-exhaustive review, we summarize the features of ongoing research efforts directed towards devising safe and effective immunotherapeutic options for mycotic diseases, encompassing work on antifungal vaccines, adoptive cell transfers, cytokines, antimicrobial peptides (AMPs), monoclonal antibodies (mAbs), and other agents.     

Ovarian Cancer Biology and Immunotherapy

Ovarian cancer is the most lethal malignancy of the female reproductive system and the fifth leading cause of cancer death in women. In the year 2012 alone, United States had 22,280 new ovarian cancer cases and 15,500 deaths were reported. About 7%–10% of ovarian cancers result from an inherited tendency to develop the disease. Ovarian cancer has the ability to escape the immune system because of its pathological interactions between cancer cells and host immune cells in the tumor microenvironment create an immunosuppressive network that promotes tumor growth, protects the tumor from immune system. The levels of immune suppressive elements like regulatory T cells, plasmacytoid dendritic cells and cytokines such as IL-10, IL-6, TNF-α, and TGF-β are elevated in the tumor microenvironment. Vascular endothelial growth factor is known to have an immune suppressing role besides its angiogenic role in the tumor microenvironment. Ovarian cancer is associated with high mortality partly due to difficulties in early diagnosis and development of metastases. These problems may overcome by developing accurate mouse models that should mimic the complexity of human ovarian cancer. Such animal models are better suited to understand pathophysiology, metastases, and also for preclinical testing of targeted molecular therapeutics. Immunotherapy is an area of active investigation and off late many clinical trials is ongoing to prevent disease progression. The main aim of dendritic cells vaccination is to stimulate tumor specific effector T cells that can reduce tumor size and induce immunological memory to prevent tumor relapse.     

Immunotherapy of Diffuse Gliomas: Biological Background, Current Status and Future Developments

Despite aggressive multimodal treatment approaches, the prognosis for patients with diffuse gliomas remains disappointing. Glioma cells often extensively infiltrate in the surrounding brain parenchyma, a phenomenon that helps them to escape surgical removal, radiation exposure and chemotherapy. Moreover, conventional therapy is often associated with considerable local and systemic side effects. Therefore, the development of novel therapeutic approaches is essential to improve the outcome of these patients. Immunotherapy offers the opportunity to specifically target residual radio—and chemoresistant tumor cells without damaging healthy neighboring brain tissue. Significant progress has been made in recent years both in understanding the mechanisms of immune regulation in the central nervous system (CNS) as well as tumor-induced and host-mediated immunosuppression elicited by gliomas. In this review, after discussing the special requirements needed for the initiation and control of immune responses in the CNS, we focus on immunological phenomena observed in glioma patients, discuss different immunological approaches to attack glioma-associated target structures and touch on further strategies to improve the efficacy of immunotherapy of gliomas.     

Promising approaches in cancer immunotherapy

Immunotherapy is a promising field, which enhances and harnesses the powers of the host immune system against cancer and in recent years, has become a major application of the fundamental research of cancer immunology. Cancer immunotherapy is often more targeted than non-specific therapy approaches, including radiotherapy or chemotherapy, as the immune system can be trained to remember cancer cells, highlighting a durable approach that can be maintained after the treatment completion. Immunotherapy functions by directing the immune system to attack the tumour cells via targeting tumour antigens, also enhancing the existing anti-tumour immune responses. Current strategies include non-specific immunotherapy, cancer vaccines, oncolytic virus therapy, monoclonal antibodies, immune checkpoints and T cell therapy. The combination of effective approaches can increase the immunotherapy efficacy, leading to durable anti-tumour immune responses. This review will discuss the immunotherapy approaches, particularly immune checkpoints and T cell therapy, which are the most common clinical applications in cancer immunotherapy.     

IL—6基因转染的瘤苗体内诱导的抗肿瘤免疫功能与效果

经丝裂霉素C体外处理后,将IL-6基因转染的、高分泌的IL-6的B16黑色素瘤细胞制成瘤苗。结果发现,体内注射IL-6基因转染的瘤苗后,小鼠脾脏CTL活性、NK活性及IL-2诱导的LAK活性显著升高。经IL-6基因转染瘤苗体内治疗后,荷瘤小鼠的皮下肿瘤生长显著减慢、肺转移结节数显著降低、存活期显著延长,若同时合用低剂量IL-2,则上述治疗效果更好。可见IL-6基因转染的瘤苗能有效地通过诱导机体抗肿瘤免疫功能而发挥抗肿瘤作用,与低剂量IL-2合用后,IL-6基因转染的瘤苗的抗肿瘤效果更佳。     

Dendritic Cell-Based Immunotherapy

Dendritic cells (DCs) play a crucial role in the induction of antigen-specific T-cell responses, and therefore their use for the active immunotherapy of malignancies has been studied with considerable interest. More than a decade has passed since the publication of the first clinical data of DC-based vaccines, and through this and subsequent studies, a number of important developmental insights have been gleaned. These include the ideal source and type of DCs, the discovery of novel antigens and methods of loading DCs, the role of DC maturation, and the most efficient route of immunization. The generation of immune responses against tumor antigens after DC immunization has been demonstrated, and favorable clinical responses have been reported in some patients; however, it is difficult to pool the results as a whole, and thus the body of data remains inconclusive, in part because of varying DC preparation and vaccination protocols, the use of different forms of antigens, and, most importantly, a lack of rigorous criteria for defining clinical responses. As such, the standardization of clinical and immunologic criteria utilized, as well as DC preparations employed, will allow for the comparison of results across multiple clinical studies and is required in order for future trials to measure the true value and role of this treatment modality. In addition, issues regarding the optimal dose and clinical setting for the application of DC vaccines remain to be resolved, and recent clinical studies have been designed to begin to address these questions.