Distinct role of antigen-specific T helper type 1 (Th1) and Th2 cells in tumor eradication in vivo

Interactions between immune challenges and cancer cells proliferation: timing does matter!

The immune system is a key component of malignant cell control and it is also involved in the elimination of pathogens that threaten the host. Despite our body is permanently exposed to a myriad of pathogens, the interference of such infections with the immune responses against cancer has been poorly investigated. Through a mathematical model, we show that the frequency, the duration and the action (positive or negative) of immune challenges may significantly impact tumor proliferation. First, we observe that a long immunosuppressive challenge increases accumulation of cancerous cells only if it occurs 14 years after the beginning of immunosenescence. However, short immune challenges result in an even greater accumulation of cancerous cells for the same total duration of immunosuppression. Finally, we show that short challenges of immune activation could lead to a slightly decrease in cancerous cell accumulation compared to a long one. Our results predict that frequent and acute immune challenges could have a different and in some extent higher impact on cancer risk than persistent ones even they have been much less studied in cancer epidemiology. These results are discussed regarding the existing empirical evidences and we suggest potential novel indirect role of infectious diseases on cancer incidence which should be investigated to improve prevention strategies against cancer.

Adoptive Transfer of Tumor-Specific Th2 Cells Eradicates Tumors by Triggering an In Situ Inflammatory Immune Response

Adoptive cell therapy (ACT) trials to date have focused on transfer of autologous tumor-specific cytotoxic CD8⁺ T cells; however, the potential of CD4⁺ T helper (Th) cells for ACT is gaining interest. While encouraging results have been reported with IFNγ-producing Th1 cells, tumor-specific Th2 cells have been largely neglected for ACT due to their reported tumor-promoting properties. In this study, we tested the efficacy of idiotype-specific Th2 cells for the treatment of mice with MHC class II-negative myeloma. Th2 ACT efficiently eradicated subcutaneous myeloma in an antigen-specific fashion. Transferred Th2 cells persisted in vivo and conferred long-lasting immunity. Cancer eradication mediated by tumor-specific Th2 cells did not require B cells, natural killer T cells, CD8⁺ T cells, or IFNγ. Th2 ACT was also curative against B-cell lymphoma. Upon transfer, Th2 cells induced a type II inflammation at the tumor site with massive infiltration of M2-type macrophages producing arginase. In vivo blockade of arginase strongly inhibited Th2 ACT, consistent with a key role of arginase and M2 macrophages in myeloma elimination by Th2 cells. These results illustrate that cancer eradication may be achieved by induction of a tumor-specific Th2 inflammatory immune response at the tumor site. Thus, ACT with tumor-specific Th2 cells may represent a highly efficient immunotherapy protocol against cancer. Cancer Res; 76(23); 6864-76. ©2016 AACR.

Biomedical applications of glycosylphosphatidylinositol-anchored proteins

Glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-APs) use a unique posttranslational modification to link proteins to lipid bilayer membranes. The anchoring structure consists of both a lipid and carbohydrate portion and is highly conserved in eukaryotic organisms regarding its basic characteristics, yet highly variable in its molecular details. The strong membrane targeting property has made the anchors an interesting tool for biotechnological modification of lipid membrane-covered entities from cells through extracellular vesicles to enveloped virus particles. In this review, we will take a closer look at the mechanisms and fields of application for GPI-APs in lipid bilayer membrane engineering and discuss their advantages and disadvantages for biomedicine.

Groth B. Tumour-specific CD4 T cells eradicate melanoma via indirect recognition of tumour-derived antigen

The importance of CD4 T cells in tumour immunity has been increasingly recognised, with recent reports describing robust CD4 T cell-dependent tumour control in mice whose immune-regulatory mechanisms have been disturbed by irradiation, chemotherapy, immunomodulatory therapy and/or constitutive immunodeficiency. Tumour control in such models has been attributed in large part to direct Major Histocompatibility Complex (MHC) class II-dependent CD4 T cell killing of tumour cells. To test whether CD4 T cells can eradicate tumours without directly killing tumour cells, we developed an animal model in which tumour-derived antigen could be presented to T-cell receptor (TCR)-transgenic CD4 T cells by host but not tumour MHC class II molecules. In I-E(+) mice bearing I-E(null) tumours, naive I-E-restricted CD4 T cells proliferated locally in tumour-draining lymph nodes after recognising tumour-derived antigen on migratory dendritic cells. In lymphopaenic but not immunosufficient hosts, CD4 T cells differentiated into polarised T helper type 1 (Th1) cells expressing interferon gamma (IFNγ), tumor necrosis factor alpha (TNFα) and interleukin (IL)-2 but little IL-17, and cleared established tumours. Tumour clearance was enhanced by higher TCR affinity for tumour antigen-MHC class II and was critically dependent on IFNγ, as demonstrated by early tumour escape in animals treated with an IFNγ blocking antibody. Thus, CD4 T cells and IFNγ can control tumour growth without direct T-cell killing of tumour cells, and without requiring additional adaptive immune cells such as CD8 T cells and B cells. Our results support a role for effective CD4 T cell-dependent tumour immunity against MHC class II-negative tumours.

IL-6 down-regulates HLA class II expression and IL-12 production of human dendritic cells to impair activation of antigen-specific CD4(+) T cells

Immunosuppression in tumor microenvironments critically affects the success of cancer immunotherapy. Here, we focused on the role of interleukin (IL)-6/signal transducer and activator of transcription (STAT3) signaling cascade in immune regulation by human dendritic cells (DCs). IL-6-conditioned monocyte-derived DCs (MoDCs) impaired the presenting ability of cancer-related antigens. Interferon (IFN)-γ production attenuated by CD4(+) T cells co-cultured with IL-6-conditioned MoDCs corresponded with decreased DC IL-12p70 production. Human leukocyte antigen (HLA)-DR and CD86 expression was significantly reduced in CD11b(+)CD11c(+) cells obtained from peripheral blood mononuclear cells (PBMCs) of healthy donors by IL-6 treatment and was STAT3 dependent. Arginase-1 (ARG1), lysosomal protease, cathepsin L (CTSL), and cyclooxygenase-2 (COX2) were involved in the reduction of surface HLA-DR expression. Gene expressions of ARG1, CTSL, COX2, and IL6 were higher in tumor-infiltrating CD11b(+)CD11c(+) cells compared with PBMCs isolated from colorectal cancer patients. Expression of surface HLA-DR and CD86 on CD11b(+)CD11c(+) cells was down-regulated, and T cell-stimulating ability was attenuated compared with PBMCs, suggesting that an immunosuppressive phenotype might be induced by IL-6, ARG1, CTSL, and COX2 in tumor sites of colorectal cancer patients. There was a relationship between HLA-DR expression levels in tumor tissues and the size of CD4(+) T and CD8(+) T cell compartments. Our findings indicate that IL-6 causes a dysfunction in human DCs that activates cancer antigen-specific Th cells, suggesting that blocking the IL-6/STAT3 signaling pathway might be a promising strategy to improve cancer immunotherapy.

Metal based nanoparticles as cancer antigen delivery vehicles for macrophage based antitumor vaccine

In the present study, we would like to evaluate the efficacy of modified metal oxide nanoparticles (NPs) as cancer antigen delivery vehicles for macrophage (MФs) based antitumor vaccine. The cobalt oxide nanoparticles (CoO NPs) were promising tools for delivery of antigens to antigen presenting cells and have induced an antitumor immune response. Synthesized CoO NPs were modified by N-phosphonomethyliminodiacetic acid (PMIDA), facilitated the conjugation of lysate antigen, i.e. cancer antigen derived from lysis of cancer cells. The cancer cell lysate antigen conjugated PMIDA-CoO NPs (Ag-PMIDA-CoO NPs) successfully activated macrophage (MФ) evident by the increasing the serum IFN-γ and TNF-α level. Immunization of mice with the Ag-PMIDA-CoO NPs constructed an efficient immunological adjuvant induced anticancer IgG responses, and increased the antibody dependent cellular cytotoxicity (ADCC) response than only lysate antigen treated group to combat the cancer cell. The nanocomplexes enhanced the anticancer CD4(+)T cell response in mice. The result showed that Ag-PMIDA-CoO NPs can stimulate the immune responses over only lysate antigens, which are the most important findings in this study. These NP-mediated Ag deliveries may significantly improve the anticancer immune response by activating MФs and may act as adjuvant and will balance the pro-inflammatory and anti-inflammatory immunoresponse. The crosstalk between the activated MФ with other immune competent cells will be monitored by measuring the cytokines which illustrate the total immunological network setups.

The re-polarisation of M2 and M1 macrophages and its role on cancer outcomes

The anti-tumour and pro-tumour roles of Th1/Th2 immune cells and M1/M2 macrophages have been documented by numerous experimental studies. However, it is still unknown how these immune cells interact with each other to control tumour dynamics. Here, we use a mathematical model for the interactions between mouse melanoma cells, Th2/Th1 cells and M2/M1 macrophages, to investigate the unknown role of the re-polarisation between M1 and M2 macrophages on tumour growth. The results show that tumour growth is associated with a type-II immune response described by large numbers of Th2 and M2 cells. Moreover, we show that (i) the ratio k of the transition rates k12 (for the re-polarisation M1→M2) and k21 (for the re-polarisation M2→M1) is important in reducing tumour population, and (ii) the particular values of these transition rates control the delay in tumour growth and the final tumour size. We also perform a sensitivity analysis to investigate the effect of various model parameters on changes in the tumour cell population, and confirm that the ratio k alone and the ratio of M2 and M1 macrophage populations at earlier times (e.g., day 7) cannot always predict the final tumour size.

Vaccines versus immunotherapy: overview of approaches in deciding between options

This review compares the optimal use of vaccines vs. other forms of immunotherapy, which includes cytokines, such as IL-2, monoclonal antibodies, such as the 'checkpoint inhibitors', against CTLA-4 and PD-1. The review includes both prophylactic and therapeutic vaccines using a variety of technologies. It is already established that vaccines can be enhanced by other immunotherapies, such as cytokines (IL-2) and there is scope for combining both of these with the 'checkpoint' antibodies. Moreover, both can be enhanced with other modalities, such as radiotherapy, ablative therapy and both high and low dose chemotherapies.

New Strategies in Engineering T-cell Receptor Gene-Modified T cells to More Effectively Target Malignancies

The immune system, T cells in particular, have the ability to target and destroy malignant cells. However, antitumor immune responses induced from the endogenous T-cell repertoire are often insufficient for the eradication of established tumors, as illustrated by the failure of cancer vaccination strategies or checkpoint blockade for most tumors. Genetic modification of T cells to express a defined T-cell receptor (TCR) can provide the means to rapidly generate large numbers of tumor-reactive T cells capable of targeting tumor cells in vivo. However, cell-intrinsic factors as well as immunosuppressive factors in the tumor microenvironment can limit the function of such gene-modified T cells. New strategies currently being developed are refining and enhancing this approach, resulting in cellular therapies that more effectively target tumors and that are less susceptible to tumor immune evasion.

Direct tumor recognition by a human CD4(+) T-cell subset potently mediates tumor growth inhibition and orchestrates anti-tumor immune responses

Tumor antigen-specific CD4(+) T cells generally orchestrate and regulate immune cells to provide immune surveillance against malignancy. However, activation of antigen-specific CD4(+) T cells is restricted at local tumor sites where antigen-presenting cells (APCs) are frequently dysfunctional, which can cause rapid exhaustion of anti-tumor immune responses. Herein, we characterize anti-tumor effects of a unique human CD4(+) helper T-cell subset that directly recognizes the cytoplasmic tumor antigen, NY-ESO-1, presented by MHC class II on cancer cells. Upon direct recognition of cancer cells, tumor-recognizing CD4(+) T cells (TR-CD4) potently induced IFN-γ-dependent growth arrest in cancer cells. In addition, direct recognition of cancer cells triggers TR-CD4 to provide help to NY-ESO-1-specific CD8(+) T cells by enhancing cytotoxic activity, and improving viability and proliferation in the absence of APCs. Notably, the TR-CD4 either alone or in collaboration with CD8(+) T cells significantly inhibited tumor growth in vivo in a xenograft model. Finally, retroviral gene-engineering with T cell receptor (TCR) derived from TR-CD4 produced large numbers of functional TR-CD4. These observations provide mechanistic insights into the role of TR-CD4 in tumor immunity, and suggest that approaches to utilize TR-CD4 will augment anti-tumor immune responses for durable therapeutic efficacy in cancer patients.

Plasma membrane vesicles decorated with glycolipid-anchored antigens and adjuvants via protein transfer as an antigen delivery platform for inhibition of tumor growth

Antigen delivered within particulate materials leads to enhanced antigen-specific immunity compared to soluble administration of antigen. However, current delivery approaches for antigen encapsulated in synthetic particulate materials are limited by the complexity of particle production that affects stability and immunogenicity of the antigen. Herein, we describe a protein delivery system that utilizes plasma membrane vesicles (PMVs) derived from biological materials such as cultured cells or isolated tissues and a simple protein transfer technology. We show that these particulate PMVs can be easily modified within 4 h by a protein transfer process to stably incorporate a glycosylphosphatidylinositol (GPI)-anchored form of the breast cancer antigen HER-2 onto the PMV surface. Immunization of mice with GPI-HER-2-modified-PMVs induced strong HER-2-specific antibody responses and protection from tumor challenge in two different breast cancer models. Further incorporation of the immunostimulatory molecules IL-12 and B7-1 onto the PMVs by protein transfer enhanced tumor protection and induced beneficial Th1 and Th2-type HER-2-specific immune responses. Since protein antigens can be easily converted to GPI-anchored forms, these results demonstrate that isolated plasma membrane vesicles can be modified with desired antigens along with immunostimulatory molecules by protein transfer and used as a vaccine delivery vehicle to elicit potent antigen-specific immunity.

The mechanisms of genetically modified vaccinia viruses for the treatment of cancer

The use of oncolytic viruses for the treatment of cancer is an emerging field of cancer research and therapy. Oncolytic viruses are designed to induce tumor specific immunity while replicating selectively within cancer cells to cause lysis of the tumor cells. While there are several forms of oncolytic viruses, the use of vaccinia viruses for oncolysis may be more beneficial than other forms of oncolytic viruses. For example, vaccinia viruses have been shown to exert their anti-tumor effects through genetic engineering strategies which enhance their therapeutic efficacy. This paper will address some of the most common forms of genetically modified vaccinia viruses and will explore the mechanisms whereby they selectively target, enter and destroy cancer cells. Furthermore, this review will highlight how vaccinia viruses activate host immune responses against cancer cells and will address clinical trials evaluating the tumor-directed and killing efficacy of these viruses against solid tumors.

Myeloid Cells as Targets for Therapy in Solid Tumors

It is well established that cancer development ensues based on reciprocal interactions between genomically altered neoplastic cells and diverse populations of recruited "host" cells co-opted to support malignant progression. Among the host cells recruited into tumor microenvironments, several subtypes of myeloid cells, including macrophages, monocytes, dendritic cells, and granulocytes contribute to tumor development by providing tumor-promoting factors as well as a spectrum of molecules that suppress cytotoxic activities of T lymphocytes. Based on compelling preclinical data revealing that inhibition of critical myeloid-based programs leads to tumor suppression, novel immune-based therapies and approaches are now entering the clinic for evaluation. This review discusses mechanisms underlying protumorigenic programming of myeloid cells and discusses how targeting of these has potential to attenuate solid tumor progression via the induction and of mobilization CD8 cytotoxic T cell immunity.

Knockdown of T-bet expression in Mart-127-35 -specific T-cell-receptor-engineered human CD4(+) CD25(-) and CD8(+) T cells attenuates effector function

Gene transfer to create tumour epitope-specific cytolytic T cells for adoptive immunotherapy of cancer remains an area of active inquiry. When the Mart-127-35 -specific DMF5 T-cell receptor (TCR) is transferred into peripheral human CD4(+) T cells, the reprogrammed cells exhibit a T helper type 1 (Th1) phenotype with significant multifactorial effector capabilities. The T-bet transcription factor plays an important role in determination of the Th1 differentiation pathway. To gain a deeper understanding of how T-bet controls the outcome of human T-cell reprogramming by gene transfer, we developed a system for examining the effects of short hairpin RNA-mediated T-bet gene knockdown in sorted cell populations uniformly expressing the knockdown construct. In this system, using activated peripheral human CD4(+)  CD25(-) and CD8(+) T cells, T-bet knockdown led to attenuation of the interferon-γ response to both antigen-specific and non-specific TCR stimulation. The interleukin-2 (IL-2) antigen-specific response was not attenuated by T-bet knockdown. Also, in TCR-reprogrammed CD8(+) cells, the cytolytic effector response was attenuated by T-bet knockdown. T-bet knockdown did not cause redirection into a Th2 differentiation pathway, and no increased IL-4, IL-10, or IL-17 response was detected in this system. These results indicate that T-bet expression is required for maintenance of the CD4(+)  CD25(-) and CD8(+) effector phenotypes in TCR-reprogrammed human T cells. They also suggest that the activation protocol necessary for transduction with retrovectors and lentivectors may commit the reprogrammed cells to the Th1 phenotype, which cannot be altered by T-bet knockdown but that there is, nevertheless, a continuous requirement of T-bet expression for interferon-γ gene activation.

CD4 T-cell subsets and tumor immunity: the helpful and the not-so-helpful

Research over the past decade has revealed the increasingly complex biologic features of the CD4(+) T-cell lineage. This T-cell subset, which was originally defined on the basis of helper activity in antibody responses, expresses receptors that recognize peptides that have been processed and presented by specialized antigen-presenting cells. At the core of the adaptive immune response, CD4 T cells display a large degree of plasticity and the ability to differentiate into multiple sublineages in response to developmental and environmental cues. These differentiated sublineages can orchestrate a broad range of effector activities during the initiation, expansion, and memory phase of an immune response. The contribution of CD4 cells to host defense against pathogenic invasion and regulation of autoimmunity is now well established. Emerging evidence suggests that CD4 cells also actively participate in shaping antitumor immunity. Here, we outline the biologic properties of CD4 T-cell subsets with an emphasis on their contribution to the antitumor response.

Influenza virus-like particles engineered by protein transfer with tumor-associated antigens induces protective antitumor immunity

Delivery of antigen in particulate form using either synthetic or natural particles induces stronger immunity than soluble forms of the antigen. Among naturally occurring particles, virus-like particles (VLPs) have been genetically engineered to express tumor-associated antigens (TAAs) and have shown to induce strong TAA-specific immune responses due to their nano-particulate size and ability to bind and activate antigen-presenting cells. In this report, we demonstrate that influenza VLPs can be modified by a protein transfer technology to express TAAs for induction of effective antitumor immune responses. We converted the breast cancer HER-2 antigen to a glycosylphosphatidylinositol (GPI)-anchored form and incorporated GPI-HER-2 onto VLPs by a rapid protein transfer process. Expression levels on VLPs depended on the GPI-HER-2 concentration added during protein transfer. Vaccination of mice with protein transferred GPI-HER-2-VLPs induced a strong Th1 and Th2-type anti-HER-2 antibody response and protected mice against a HER-2-expressing tumor challenge. The Soluble form of GPI-HER-2 induced only a weak Th2 response under similar conditions. These results suggest that influenza VLPs can be enriched with TAAs by protein transfer to develop effective VLP-based subunit vaccines against cancer without chemical or genetic modifications and thus preserve the immune stimulating properties of VLPs for easier production of antigen-specific therapeutic cancer vaccines.

Modeling the specific CD4+ T cell response against a tumor neoantigen

The antitumor activity of CD4(+) T cells is increasingly acknowledged in both humans and mice. The involved mechanisms have been mostly studied using transplanted tumor mouse systems. In these models, many tumor cells die at the time of implantation leading to the release of Ag in an inflammatory context contrasting with the slow and nondestructive growth of early-stage human tumors. In this study, we show that the presentation of a MHC class II-restricted model Ag (male, DBY) released by dying tumor cells may last more than 4 wk. The duration of Ag presentation varies according to the way the cells are killed before implantation. To avoid this artifactual early priming of the host precluding the study of the interactions between the immune system and tumors at the steady state, we generated a cell line expressing the DBY Ag in an inducible manner. Ag expression can be efficiently induced in vivo several days after tumor implantation. We show that the Ag reaches the lymph node and activates naive CD4(+) T cells to proliferate and recirculate. We did not observe de novo induction of tumor-specific regulatory T cells. However, we observed Th1/Th17 effector cells in the tumor draining lymph node and tumors. Thus, when a neoantigen appears in established tumors, the immune system is not ignorant and naive CD4(+) T cells are not tolerized. This opens up the possibility of therapeutic vaccines improving the immune response toward tumor-specific neoantigens.

Metastatic melanoma cells evade immune detection by silencing STAT1

Transcriptional activation of major histocompatibility complex (MHC) I and II molecules by the cytokine, interferon γ (IFN-γ), is a key step in cell-mediated immunity against pathogens and tumors. Recent evidence suggests that suppression of MHC I and II expression on multiple tumor types plays important roles in tumor immunoevasion. One such tumor is malignant melanoma, a leading cause of skin cancer-related deaths. Despite growing awareness of MHC expression defects, the molecular mechanisms by which melanoma cells suppress MHC and escape from immune-mediated elimination remain unknown. Here, we analyze the dysregulation of the Janus kinase (JAK)/STAT pathway and its role in the suppression of MHC II in melanoma cell lines at the radial growth phase (RGP), the vertical growth phase (VGP) and the metastatic phase (MET). While RGP and VGP cells both express MHC II, MET cells lack not only MHC II, but also the critical transcription factors, interferon response factor (IRF) 1 and its upstream activator, signal transducer and activator of transcription 1 (STAT1). Suppression of STAT1 in vitro was also observed in patient tumor samples, suggesting STAT1 silencing as a global mechanism of MHC II suppression and immunoevasion.

Optimizing dendritic cell-based approaches for cancer immunotherapy

Dendritic cells (DC) are professional antigen-presenting cells uniquely suited for cancer immunotherapy. They induce primary immune responses, potentiate the effector functions of previously primed T-lymphocytes, and orchestrate communication between innate and adaptive immunity. The remarkable diversity of cytokine activation regimens, DC maturation states, and antigen-loading strategies employed in current DC-based vaccine design reflect an evolving, but incomplete, understanding of optimal DC immunobiology. In the clinical realm, existing DC-based cancer immunotherapy efforts have yielded encouraging but inconsistent results. Despite recent U.S. Federal and Drug Administration (FDA) approval of DC-based sipuleucel-T for metastatic castration-resistant prostate cancer, clinically effective DC immunotherapy as monotherapy for a majority of tumors remains a distant goal. Recent work has identified strategies that may allow for more potent "next-generation" DC vaccines. Additionally, multimodality approaches incorporating DC-based immunotherapy may improve clinical outcomes.

Artificially synthesized helper/killer-hybrid epitope long peptide (H/K-HELP): preparation and immunological analysis of vaccine efficacy

To elucidate the immunologic mechanisms of artificially synthesized helper/killer-hybrid epitope long peptide (H/K-HELP), which indicated a great vaccine efficacy in human cancers, we prepared ovalbumin (OVA)-H/K-HELP by conjugating killer and helper epitopes of OVA-model tumor antigen via a glycine-linker. Vaccination of C57BL/6 mice with OVA-H/K-HELP (30 amino acids) but not with short peptides mixture of class I-binding peptide (8 amino-acids) and class II-binding peptide (17 amino-acids) combined with adjuvant CpG-ODN (cytosine-phosphorothioate-guanine oligodeoxynucleotides), induced higher numbers of OVA-tetramer-positive CTL with concomitant activation of IFN-γ-producing CD4(+) Th1 cells. However, replacement of glycine-linker of OVA-H/K-HELP with other peptide-linker caused a significant decrease of vaccine efficacy of OVA-H/K-HELP. In combination with adjuvant CpG-ODN, OVA-H/KHELP exhibited greater vaccine efficacy compared with short peptides vaccine, in both preventive and therapeutic vaccine models against OVA-expressing EG-7 tumor. The elevated vaccine efficacy of OVAH/K-HELP might be derived from the following mechanisms: (i) selective presentation by only professional dendritic cells (DC) in vaccinated draining lymph node (dLN); (ii) a long-term sustained antigen presentation exerted by DC to stimulate both CTL and Th1 cells; (iii) formation of three cells interaction among DC, Th and CTL. In comparative study, H/K-HELP indicated stronger therapeutic vaccine efficacy compared with that of extended class I synthetic long peptide, indicating that both the length of peptide and the presence of Th epitope peptide were crucial aspects for preparing artificially synthesized H/K-HELP vaccine.

Skewed T-helper (Th)1/2- and Th17/T regulatory‑cell balances in patients with renal cell carcinoma

The characterization of CD4⁺ T-cell subsets reflects the immune status and is important in the maintenance of tumorigenesis and homeostasis. To identify changes in the balance of T helper (Th)1, Th2, Th17 and regulatory T cells (Treg) in individuals with renal cell carcinoma (RCC), the present study investigated a total of 131 patients with RCC and 36 healthy volunteers. The number of CD4⁺ T-bet⁺ cells, CD4⁺ GATA binding protein 3⁺ cells, CD4⁺ RAR-related orphan receptor γt⁺ cells, CD4⁺ CD25^hi CD127^lo CD45RA⁻ cells and CD4⁺ CD25^hi CD127^lo CD45RA⁺ cells, defined as Th1, Th2, Th17, activated and naïve Treg cells, respectively, were detected in the peripheral blood using flow cytometric analysis. In addition, tumor-infiltrating forkhead box P3 (Foxp3)⁺ cells were examined using immunohistochemistry. Compared with healthy volunteers, a significant decrease in the peripheral percentages of Th1, activated and naïve Treg cells was observed in patients with RCC, while those of the Th2 and Th17 cells were increased. In particular, as the tumor stage and grade progressed, the levels of Th1, activated and naïve Treg cells in the peripheral blood decreased; however, the levels of Th2 and Th17 cells increased. Furthermore, the number of tumor-infiltrating Foxp3⁺ cells increased with increasing tumor stage. These results demonstrated that the balance of Th1 and Th2 cells was skewed towards the Th2 profile and the balance of Th17 and Treg cells was skewed towards the Th17 profile in the peripheral blood of patients with renal cell carcinoma (RCC) and Treg cells were recruited to the tumor sites. Therefore, dysfunctional host anti-tumor immunity was observed in patients with RCC, with a skewed Th1/Th2 and Th17/Treg balance.

Anti-metastatic study of liposome-encapsulated all trans retinoic acid (ATRA) in B16F10 melanoma cells-implanted C57BL/6 mice

B16F10 cells-induced C57BL/6 mice were divided into several groups and the free all trans retinoic acid (ATRA) and liposome-encapsulated ATRA were given for 21 days. The encapsulated ATRA treatment lowered the oxidative stress and lipid profile near to the normal level in the drug-treated mice. Encapsulated ATRA treatment showed substantial decrease in serum cytokines and increase in lifespan when compared with free ATRA treatment. These results imply that the liposome-encapsulated ATRA may help to achieve a higher level of ATRA in comparison with free ATRA treatment and helps to enhance anticancer drug delivery in liposome-encapsulated ATRA treatment.

Identification of novel helper epitope peptides of Survivin cancer-associated antigen applicable to developing helper/killer-hybrid epitope long peptide cancer vaccine

We identified novel helper epitope peptides of Survivin cancer antigen, which are presented to both HLA-DRB1*01:01 and DQB1*06:01. The helper epitope also contained three distinct Survivin-killer epitopes presented to HLA-A*02:01 and A*24:02. This 19 amino-acids epitope peptide (SU18) induced weak responses of Survivin-specific CD4(+) and CD8(+) T cells though it contained both helper and killer epitopes. To enhance the vaccine efficacy, we synthesized a long peptide by conjugating SU18 peptide and another DR53-restricted helper epitope peptide (SU22; 12 amino-acids) using glycine-linker. We designated this artificial 40 amino-acids long peptide containing two helper and three killer epitopes as Survivin-helper/killer-hybrid epitope long peptide (Survivin-H/K-HELP). Survivin-H/K-HELP allowed superior activation of IFN-γ-producing CD4(+) Th1 cells and CD8(+) Tc1 cells compared with the mixture of its component peptides (SU18 and SU22) in the presence of OK-432-treated monocyte-derived DC (Mo-DC). Survivin-H/K-HELP-pulsed Mo-DC pretreated with OK-432 also exhibited sustained antigen-presentation capability of stimulating Survivin-specific Th1 cells compared with Mo-DC pulsed with a mixture of SU18 and SU22 short peptides. Moreover, we demonstrated that Survivin-H/K-HELP induced a complete response in a breast cancer patient with the induction of cellular and humoral immune responses. Thus, we believe that an artificially synthesized Survivin-H/K-HELP will become an innovative cancer vaccine.

How Do CD4(+) T Cells Detect and Eliminate Tumor Cells That Either Lack or Express MHC Class II Molecules?

CD4⁺ T cells contribute to tumor eradication, even in the absence of CD8⁺ T cells. Cytotoxic CD4⁺ T cells can directly kill MHC class II positive tumor cells. More surprisingly, CD4⁺ T cells can indirectly eliminate tumor cells that lack MHC class II expression. Here, we review the mechanisms of direct and indirect CD4⁺ T cell-mediated elimination of tumor cells. An emphasis is put on T cell receptor (TCR) transgenic models, where anti-tumor responses of naïve CD4⁺ T cells of defined specificity can be tracked. Some generalizations can tentatively be made. For both MHCII^POS and MHCII^NEG tumors, presentation of tumor-specific antigen by host antigen-presenting cells (APCs) appears to be required for CD4⁺ T cell priming. This has been extensively studied in a myeloma model (MOPC315), where host APCs in tumor-draining lymph nodes are primed with secreted tumor antigen. Upon antigen recognition, naïve CD4⁺ T cells differentiate into Th1 cells and migrate to the tumor. At the tumor site, the mechanisms for elimination of MHCII^POS and MHCII^NEG tumor cells differ. In a TCR-transgenic B16 melanoma model, MHCII^POS melanoma cells are directly killed by cytotoxic CD4⁺ T cells in a perforin/granzyme B-dependent manner. By contrast, MHCII^NEG myeloma cells are killed by IFN-γ stimulated M1-like macrophages. In summary, while the priming phase of CD4⁺ T cells appears similar for MHCII^POS and MHCII^NEG tumors, the killing mechanisms are different. Unresolved issues and directions for future research are addressed.

FbaA- and M protein-based multi-epitope vaccine elicits strong protective immune responses against group A streptococcus in mouse model

We report the construction of a recombinant multivalent vaccine against group A streptococcus (GAS), designated F7M5. It contains seven predominant epitopes of FbaA identified by phage display technology, five non-tissue cross-reactive M protein fragments expressed on four selected serotypes prevalent in China, a Trojan antigen (TA) and a poly-alanine DR epitope (PADRE). BALB/c mice were immunized subcutaneously with F7M5 formulated with Freund's adjuvant, using recombinant FbaA and M protein in parallel as control. Using enzyme-linked immunosorbent assay (ELISA), mouse immune sera were assayed for IgG titers, IgG subclasses, and binding of F7M5 with M1GAS. Results indicated that the multivalent vaccine was highly immunogenic and elicited a balanced IgG1/IgG2a response. We also tested the reactivity of F7M5 to antistreptolysin O (ASO) antibodies in sera of GAS-infected patients and found a 95.8% positive rate, indicating that the epitopes of the vaccine were widely expressed in the prevalent serotypes of GAS. More importantly, the F7M5 vaccine elicited strong protective immune responses against lethal-dose challenge with a survival rate of 90%, but induced no cross-reactions or pathological lesions in mouse model, suggesting that F7M5 can be further developed as an effective and safe anti-GAS vaccine.

Identification of a meiosis-specific protein, MEIOB, as a novel cancer/testis antigen and its augmented expression in demethylated cancer cells

Cancer/testis (CT) antigens, which are expressed in various cancer cells but not in normal cells except germline cells of the testis, have been used as targets for cancer vaccine therapy. 5-Aza-2'-deoxycytidine (DAC), a potent inhibitor of genomic and promoter-specific DNA methylation, inhibits DNA methyltransferase activity and is reported to induce the expression of certain CT antigens by the demethylation of promoter CpG islands of the treated cells. Here, using DAC-treated cancer cells, we searched for novel attractive target molecules that would be useful for cancer immunotherapy and found a meiosis-specific protein, meiosis specific with OB domains (MEIOB), to be a novel CT antigen. Indeed, the MEIOB gene is expressed only in the testis and not in other normal tissues. The mRNA expression of MEIOB was greatly enhanced in several lung cancer cell lines after the treatment with DAC. Furthermore, we identified a variety of helper epitopes of the MEIOB antigen, which were recognized by MEIOB antigen-specific T cells in a HLA-restriction manner. Finally, we demonstrated that IFN-γ production of MEIOB peptide-specific helper T cells in response to HLA-matched cancer cells was greatly augmented by treatment with DAC and IFN-γ. Taken together, these findings show DAC to be a promising tool for finding novel CT antigens and for developing a future novel combination cancer vaccine chemotherapy.

TCR-Engineered T Cells Meet New Challenges to Treat Solid Tumors: Choice of Antigen, T Cell Fitness, and Sensitization of Tumor Milieu

Adoptive transfer of T cells gene-engineered with antigen-specific T cell receptors (TCRs) has proven its feasibility and therapeutic potential in the treatment of malignant tumors. To ensure further clinical development of TCR gene therapy, it is necessary to target immunogenic epitopes that are related to oncogenesis and selectively expressed by tumor tissue, and implement strategies that result in optimal T cell fitness. In addition, in particular for the treatment of solid tumors, it is equally necessary to include strategies that counteract the immune-suppressive nature of the tumor micro-environment. Here, we will provide an overview of the current status of TCR gene therapy, and redefine the following three challenges of improvement: “choice of target antigen”; “fitness of T cells”; and “sensitization of tumor milieu.” We will categorize and discuss potential strategies to address each of these challenges, and argue that advancement of clinical TCR gene therapy critically depends on developments toward each of the three challenges.

Programmed death 1 and B and T lymphocyte attenuator immunoreceptors and their association with malignant T-lymphoproliferative disorders: brief review

Malignant T-cell lymphoproliferative diseases are relatively rare. T cells are activated through the T-cell receptor with the aid of costimulating molecules that can be either excitatory or inhibitory. Such pathways have been also implicated in mechanisms of malignant T-cell lymphoproliferative diseases' persistence and relapse by circumventing immune responses. To date, three major immunoinhibitory molecules have been recognized, namely programmed cell death-1 (PD-1), B and T lymphocyte attenuator (BTLA) and cytotoxic T lymphocyte antigen 4 (CTLA-4). Although CTLA-4 is considered the 'gatekeeper' of immune tolerance, PD-1 negatively regulates immune responses broadly, whereas BTLA activation has been shown to inhibit CD8+ cancer-specific T cells. Both PD-1 and BTLA downregulate proximal T-cell receptor signalling cascade and are involved in immune evasion of leukaemias and lymphomas, even after allogeneic stem cell transplantation. These immunoregulatory molecules can have seemingly a synergistic effect on weakening the immune response of patients with haematological malignancies, and their manipulation represents a very active field of preclinical as well as clinical interest.

Local immune response predicts survival in patients with thick (t4) melanomas

BACKGROUND

Tumor infiltrating lymphocytes (TIL) and histological regression in primary melanoma are generally considered indicators of the local immune response but their roles as prognostic factors have been variably reported. We examined the prognostic role of these variables in patients with high risk (T4) primary melanomas in a large series of patients with long-term follow-up.

METHODS

From a prospectively maintained cohort of patients diagnosed between 1971 and 2004, 161 patients were retrospectively identified with primary thick melanomas (>4 mm), no clinical evidence of regional nodal disease (RND) at diagnosis and complete histopathologic data. Univariate and multivariate Cox regression models were performed to identify clinical and histopathologic predictors of disease-specific survival (DSS) and to identify subgroups with differential survival.

RESULTS

Factors significantly associated with decreased DSS by univariate analysis included male gender, age ≥ 60 years, axial anatomic location, presence of ulceration, RND, absence of TIL, and presence of regression. In the final multivariate model, TIL and regression, as interacting variables, and RND status remained significantly associated with DSS. In the presence of TIL, concomitant regression was associated with significantly worse survival (p ≤ 0.0001). In the absence of TIL, there was no effect of regression on survival (p = 0.324).

CONCLUSIONS

Primary TIL and regression status and RND status are independently associated with melanoma-specific survival in patients with T4 melanomas; presence of TIL in the primary melanoma with concomitant radial growth phase regression is associated with a poor prognosis and may reflect an ineffective local regional immune response.

Immunomodulatory effect of Stichopus japonicus acid mucopolysaccharide on experimental hepatocellular carcinoma in rats

Stichopus japonicus acid mucopolysaccharide (SJAMP) is an important biologically active compound that can be extracted from the body wall of the sea cucumber. The present study investigated the anti-tumor and immunomodulatory effects of SJAMP in an experimental hepatocellular carcinoma (HCC) model in rats. Three doses of SJAMP (17.5 mg/kg, 35 mg/kg, and 70 mg/kg administered 5 days/week via oral gavage) were given to rats with diethylnitrosamine (DEN)-induced HCC. SJAMP treatment significantly inhibited DEN-induced HCC by reducing both the number and mean volume of nodules, decreasing serum a-fetoprotein (AFP) levels and proliferating cell nuclear antigen (PCNA) expression in liver, and increasing p21 expression. Furthermore, SJAMP decreased the serum levels of ALT, AST, GGT and TNF-α and increased serum IL-2. SJAMP administration also improved indices of spleen and thymus function and improved both macrophage phagocytosis and NK cell-mediated tumoricidal activity. Moreover, CD3+ and CD4+ T lymphocyte levels recovered significantly and the CD4+/CD8+ T cell ratio normalized in a dose-dependent manner. In conclusion, SJAMP effectively inhibited the growth of HCC through the stimulation of immune organs and tissue proliferation, leading to the enhancement of cellular immunity pathways in rats.

Synergy between CD8 T cells and Th1 or Th2 polarised CD4 T cells for adoptive immunotherapy of brain tumours

The feasibility of cancer immunotherapy mediated by T lymphocytes is now a clinical reality. Indeed, many tumour associated antigens have been identified for cytotoxic CD8 T cells, which are believed to be key mediators of tumour rejection. However, for aggressive malignancies in specialised anatomic sites such as the brain, a limiting factor is suboptimal tumour infiltration by CD8 T cells. Here we take advantage of recent advances in T cell biology to differentially polarise CD4 T cells in order to explore their capacity to enhance immunotherapy. We used an adoptive cell therapy approach to work with clonal T cell populations of defined specificity. Th1 CD4 T cells preferentially homed to and accumulated within intracranial tumours compared with Th2 CD4 T cells. Moreover, tumour-antigen specific Th1 CD4 T cells enhanced CD8 T cell recruitment and function within the brain tumour bed. Survival of mice bearing intracranial tumours was significantly prolonged when CD4 and CD8 T cells were co-transferred. These results should encourage further definition of tumour antigens recognised by CD4 T cells, and exploitation of both CD4 and CD8 T cell subsets to optimise T cell therapy of cancer.

Dendritic cell-based vaccines: barriers and opportunities

Dendritic cells (DCs) have several characteristics that make them an ideal vehicle for tumor vaccines, and with the first US FDA-approved DC-based vaccine in use for the treatment of prostate cancer, this technology has become a promising new therapeutic option. However, DC-based vaccines face several barriers that have limited their effectiveness in clinical trials. A major barrier includes the activation state of the DC. Both DC lineage and maturation signals must be selected to optimize the antitumor response and overcome immunosuppressive effects of the tumor microenvironment. Another barrier to successful vaccination is the selection of target antigens that will activate both CD8(+) and CD4(+) T cells in a potent, immune-specific manner. Finally, tumor progression and immune dysfunction limit vaccine efficacy in advanced stages, which may make DC-based vaccines more efficacious in treating early-stage disease. This review underscores the scientific basis and advances in the development of DC-based vaccines, focuses on current barriers to success and highlights new research opportunities to address these obstacles.

Immune system targeting by biodegradable nanoparticles for cancer vaccines

The concept of therapeutic cancer vaccines is based on the activation of the immune system against tumor cells after the presentation of tumor antigens. Nanoparticles (NPs) have shown great potential as delivery systems for cancer vaccines as they potentiate the co-delivery of tumor-associated antigens and adjuvants to dendritic cells (DCs), insuring effective activation of the immune system against tumor cells. In this review, the immunological mechanisms behind cancer vaccines, including the role of DCs in the stimulation of T lymphocytes and the use of Toll-like receptor (TLR) ligands as adjuvants will be discussed. An overview of each of the three essential components of a therapeutic cancer vaccine - antigen, adjuvant and delivery system - will be provided with special emphasis on the potential of particulate delivery systems for cancer vaccines, in particular those made of biodegradable aliphatic polyesters, such as poly(lactic-co-glycolic acid) (PLGA) and poly-ε-caprolactone (PCL). Some of the factors that can influence NP uptake by DCs, including size, surface charge, surface functionalization and route of administration, will also be considered.

CCR3, CCR4, CCR5, and CXCR3 expression in peripheral blood CD4+ lymphocytes in gastric cancer patients

Background:

CD4+(TH1, and TH2) cell groups in the point of view of chemokine receptor expression were considered in blood of stomach cancer patients.

Materials and Methods:

The percentage of blood CD4+ T cells expressing chemokine receptors (before and after gastrectomy) was determined by flow cytometry (Becton Dickinson, USA) using the following chemokine receptor antibodies: anti-CCR5, anti-CXCR3, anti-CCR3 and anti-CCR4.

Results:

The means of CD4⁺ CCR5⁺ expressing cells was 1.23% ± 0.90, 0.83% ± 0.34 and 1.34% ± 0.74 in control, pre- and post-operation groups, respectively. CD4⁺ CXCR3⁺ expressing cells were 19.09% ± 8.4, 16.95% ± 5.71 and 25.08% ± 9.31, respectively. Similar pattern was seen for CD4⁺ CCR3⁺ and CD4⁺ CCR4⁺ expressing cells. Pearson correlation analysis shows no relationship between CCR3 and CCR4 expressions on TCD4 cells (r = 0.211, P = 0.126). The complex expression TH1 (CD4⁺ CXCR3⁺ CCR5⁺) receptors determined 1.14% ± 0.54 for control group, 0.86% ± 0.49 for pre-T and 1.57% ± 0.67 for post-T group. Moreover, the TH2 (CD4⁺ CCR3⁺ CCR4⁺) expression was 1.60% ± 1.05 for control group, 1.57% ± 0.83 for pre-T and 1.27% ± 0.66 for post-treatment group. Pearson correlation analysis shows that only the CCR3 and CCR5 expression was statistically correlated (r = 0.321, P = 0.018).

Conclusion:

Due to low expression of CCR5 in TH1 and CCR3 in TH2 cells, it seems that utility of these is extremely limited for clinical evaluation, but not scientific purpose. Moreover, considering the CXCR3 for TH1 cells and CCR4 expression for TH2 cells, due to considerable expression, may be practical.

The key role of IL-6-arginase cascade for inducing dendritic cell-dependent CD4(+) T cell dysfunction in tumor-bearing mice

Evaluation of immune dysfunction during the tumor-bearing state is a critical issue in combating cancer. In this study, we initially found that IL-6, one of the cachectic factors, suppressed CD4(+) T cell-mediated immunity through downregulation of MHC class II by enhanced arginase activity of dendritic cells (DC) in tumor-bearing mice. We demonstrated that administration of Ab against IL-6R (anti-IL-6R mAb) greatly enhanced T cell responses and inhibited the growth of tumor in vivo. We also found that IL-6 upregulated the expression of arginase-1 and arginase activity of DC in vitro. Tumor-infiltrating CD11c(+) DC exhibited upregulated mRNA expression of arginase-1 but reduced expression of MHC class II in parallel with the increase in serum IL-6 levels at the late stage in tumor-bearing hosts. However, the administration of anti-IL-6R mAb into tumor-bearing mice inhibited both the downmodulation of MHC class II and the upregulation of arginase-1 mRNA levels in DC. Furthermore, we noted that N(ω)-hydroxy-L-arginine or L-arginine, an arginase-1 inhibitor, blocked the reduction in MHC class II levels on CD11c(+) DC during the tumor-bearing state. Finally, we demonstrated that the administration of N(ω)-hydroxy-L-arginine at the peritumor site significantly enhanced CD4(+) T cell responses and inhibited tumor growth. Thus, IL-6-mediated arginase activation and the subsequent reduction in MHC class II expression on DC appeared to be critical mechanisms for inducing dysfunction of the immune system in the tumor-bearing state. Blockade of the IL-6-arginase cascade is a promising tool to overcome the dysfunction of antitumor immunity in tumor-bearing hosts.

[The regulation of antitumor immune responses by helper T cells--From the bench research to the discovery of H/K-HELP cancer vaccine]

During past decades, cancer vaccine therapy has been focused on only the activation of CTL, but its therapeutic effect was not successful though long SD was induced. The failure of cancer vaccine is derived from (i) the existence of a strong tumor escape mechanisms and (ii) the ignorance of helper T cell activation. We have proposed that Th1-dominant immunity played a critical role for overcoming immunosuppressive tumor-escape mechanisms to induce tumor-specific CTL, which are essential for the complete cure of tumor and prevention of tumor recurrence. To apply these basic findings, we started a clinical trial of a novel cancer vaccine/cell therapy (Th1 cell therapy) using H/K-HELP of MAGE-A4 or Survivin cancer antigen. In phase I study, H/K-HELP consisted of both killer and helper epitopes and Th1 adjuvants (OK-432 and Montanide) were subcutaneously administered into cancer patients 4 times at 2 wks intervals. Both MAGE-A4-H/K-HELP and Survivin-H/K-HELP cancer vaccine induced cancer-specific Th1 and Tc1 immune responses and cancer-specific C-fixing antibodies (IgG1 and IgG3) in cancer patients. Moreover, Survivin-H/K-HELP vaccination induced a complete regression of chemo and radio-resistant lateral deep cervical node recurrence of triple-negative breast cancer. H/K-HELP vaccination with Th1 adjuvants or its combination with Th1 cells will become a promising cancer vaccine/cell therapy of human cancer.

Heat shock protein 90-mediated peptide-selective presentation of cytosolic tumor antigen for direct recognition of tumors by CD4(+) T cells

Tumor Ag-specific CD4(+) T cells play important functions in tumor immunosurveillance, and in certain cases they can directly recognize HLA class II-expressing tumor cells. However, the underlying mechanism of intracellular Ag presentation to CD4(+) T cells by tumor cells has not yet been well characterized. We analyzed two naturally occurring human CD4(+) T cell lines specific for different peptides from cytosolic tumor Ag NY-ESO-1. Whereas both lines had the same HLA restriction and a similar ability to recognize exogenous NY-ESO-1 protein, only one CD4(+) T cell line recognized NY-ESO-1(+) HLA class II-expressing melanoma cells. Modulation of Ag processing in melanoma cells using specific molecular inhibitors and small interfering RNA revealed a previously undescribed peptide-selective Ag-presentation pathway by HLA class II(+) melanoma cells. The presentation required both proteasome and endosomal protease-dependent processing mechanisms, as well as cytosolic heat shock protein 90-mediated chaperoning. Such tumor-specific pathway of endogenous HLA class II Ag presentation is expected to play an important role in immunosurveillance or immunosuppression mediated by various subsets of CD4(+) T cells at the tumor local site. Furthermore, targeted activation of tumor-recognizing CD4(+) T cells by vaccination or adoptive transfer could be a suitable strategy for enhancing the efficacy of tumor immunotherapy.

Therapeutic effects of autologous tumor-derived nanovesicles on melanoma growth and metastasis

Cancer vaccines with optimal tumor-associated antigens show promise for anti-tumor immunotherapy. Recently, nano-sized vesicles, such as exosomes derived from tumors, were suggested as potential antigen candidates, although the total yield of exosomes is not sufficient for clinical applications. In the present study, we developed a new vaccine strategy based on nano-sized vesicles derived from primary autologous tumors. Through homogenization and sonication of tumor tissues, we achieved high yields of vesicle-bound antigens. These nanovesicles were enriched with antigenic membrane targets but lacked nuclear autoantigens. Furthermore, these nanovesicles together with adjuvant activated dendritic cells in vitro, and induced effective anti-tumor immune responses in both primary and metastatic melanoma mouse models. Therefore, autologous tumor-derived nanovesicles may represent a novel source of antigens with high-level immunogenicity for use in acellular vaccines without compromising safety. Our strategy is cost-effective and can be applied to patient-specific cancer therapeutic vaccination.

Using monoclonal antibodies to stimulate antitumor cellular immunity

Monoclonal antibodies (mAbs) have an established role in current cancer therapy with seven approved for the treatment of a wide variety of tumors. The approved mAbs directly target tumor cells; however, it is becoming increasingly clear that as well as their direct effects, these mAbs can present antigens to the immune system. This stimulates long-lasting T-cell immunity, which may correlate with long-term survival. A more direct approach is to use mAbs to target antigens directly to antigen-presenting cells. One approach, ImmunoBody, which has just entered the clinic, stimulates antitumor immunity using mAbs genetically engineered to express tumor-specific T-cell epitopes. T cells not only respond via their T-cell receptors recognizing T-cell epitopes presented on MHC but are also influenced by stimulation of a wide variety of costimulatory molecules. mAbs targeting these molecules can also influence antitumor immunity. The main protagonist in this class of mAbs is ipilimumab, which has recently been shown to improve survival at 2 years in 23% of advanced melanoma patients. Combinations of mAbs targeting tumor antigens to activated antigen-presenting cells and mAbs targeting costimulatory receptors may provide effective therapy for a broad range of tumors.

Cytotoxic chemotherapy and CD4+ effector T cells: an emerging alliance for durable antitumor effects

Standard cytotoxic chemotherapy can initially achieve high response rates, but relapses often occur in patients and represent a severe clinical problem. As increasing numbers of chemotherapeutic agents are found to have immunostimulatory effects, there is a growing interest to combine chemotherapy and immunotherapy for synergistic antitumor effects and improved clinical benefits. Findings from recent studies suggest that highly activated, polyfunctional CD4+ effector T cells have tremendous potential in strengthening and sustaining the overall host antitumor immunity in the postchemotherapy window. This review focuses on the latest progresses regarding the impact of chemotherapy on CD4+ T-cell phenotype and function and discusses the prospect of exploiting CD4+ T cells to control tumor progression and prevent relapse after chemotherapy.

Treatment with targeted vesicular stomatitis virus generates therapeutic multifunctional anti-tumor memory CD4 T cells

A generally applicable, easy-to-use method of focusing a patient's immune system to eradicate or prevent cancer has been elusive. We are attempting to develop a targeted virus to accomplish these aims. We previously created a recombinant replicating Vesicular Stomatitis Virus that preferentially infected Her2/neu expressing breast cancer cells and showed therapeutic efficacy in an implanted Balb/c mouse tumor model. The current work shows that this therapy generated therapeutic anti-tumor CD4 T-cells against multiple tumor antigens. CD4 T-cells transferred directly from cured donor mice could eradicate established tumors in host mice. T-cells were transferred directly from donor mice and were not stimulated ex vivo. Both tumors that expressed Her2/neu and those that did not were cured by transferred T-cells. Analysis of cytokines secreted by anti-tumor memory CD4 T-cells displayed a multifunctional pattern with high levels of IFNγ, IL-4 and IL-17. Anti-tumor memory CD4 T-cells traveled to the mesenteric lymph nodes and were activated there. Treatment with targeted rrVSV is a potent immune adjuvant that generates therapeutic, multifunctional anti-tumor memory CD4 T-cells that recognize multiple tumor antigens. Immunity elicited by viral therapy is independent of host major histocompatibility complex (MHC) or knowledge of tumor antigens. Virus-induced tumor immunity could have great benefit in the prevention and treatment of tumor metastases.

First clinical trial of cancer vaccine therapy with artificially synthesized helper/ killer-hybrid epitope long peptide of MAGE-A4 cancer antigen

A patient with pulmonary metastasis of colon cancer was treated with artificially synthesized helper/killer-hybrid epitope long peptide (H/K-HELP) of MAGE-A4 cancer antigen. The patient was vaccinated with MAGE-A4-H/K-HELP combined with OK432 and Montanide ISA-51. There were no severe side-effects except for a skin reaction at the injection site. MAGE-A4-H/K-HELP induced MAGE-A4-specific Th1 and Tc1 immune responses and the production of MAGE-A4-specific complement-fixing IgG antibodies. Tumor growth and carcinoembryonic antigen tumor marker were significantly decreased in the final diagnosis. This is the first report that artificially synthesized MAGE-A4-H/K-HELP induces Th1-dependent cellular and humoral immune responses in a human cancer patient.

Identification of innate IL-5-producing cells and their role in lung eosinophil regulation and antitumor immunity

IL-5 is involved in a number of immune responses such as helminth infection and allergy. IL-5 also plays roles in innate immunity by maintaining B-1 B cells and mucosal IgA production. However, the identity of IL-5-producing cells has not been unambiguously characterized. In this report, we describe the generation of an IL-5 reporter mouse and identify IL-5-producing non-T lymphoid cells that reside in the intestine, peritoneal cavity, and lungs in naive mice. They share many characteristics with natural helper cells, nuocytes, and Ih2 cells, including surface Ags and responsiveness to cytokines. However, these phenotypes do not completely overlap with any particular one of these cell types. Innate non-T IL-5-producing cells localized most abundantly in the lung and proliferated and upregulated IL-5 production in response to IL-25 and IL-33. IL-33 was more effective than IL-25. These cells contribute to maintaining sufficient numbers of lung eosinophils and are important for eosinophil recruitment mediated by IL-25 and IL-33. Given that eosinophils are shown to possess antitumor activity, we studied lung tumor metastasis and showed that innate IL-5-producing cells were increased in response to tumor invasion, and their regulation of eosinophils is critical to suppress tumor metastasis. Genetic blockade or neutralization of IL-5 impaired eosinophil recruitment into the lung and resulted in increased tumor metastasis. Conversely, exogenous IL-5 treatment resulted in suppressed tumor metastasis and augmented eosinophil infiltration. These newly identified innate IL-5-producing cells thus play a role in tumor surveillance through lung eosinophils and may contribute to development of novel immunotherapies for cancer.