Antitumour activity mediated by CD4+ cytotoxic T lymphocytes against MHC class II-negative mouse hepatocellular carcinoma induced by dendritic cell vaccine and interleukin-12

WT1 Cancer Vaccine in Advanced Pancreatic Cancer: A Systematic Review

Advanced pancreatic cancer is one of the prominent contributors to cancer-related mortality globally. Chemotherapy, especially gemcitabine, is generally used for the treatment of advanced pancreatic cancer. Despite the treatment, the fatality rate for advanced pancreatic cancer is alarmingly high. Thus, the dire need for better treatment alternatives has drawn focus to cancer vaccinations. The Wilms tumor gene (WT1), typically associated with Wilms tumor, is found to be excessively expressed in some cancers, such as pancreatic cancer. This characteristic feature is harvested to develop cancer vaccines against WT1. This review aims to systematically summarize the clinical trials investigating the efficacy and safety of WT1 vaccines in patients with advanced pancreatic cancer. An extensive literature search was conducted on databases Medline, Web of Science, ScienceDirect, and Google Scholar using the keywords "Advanced pancreatic cancer," "Cancer vaccines," "WT1 vaccines," and "Pulsed DC vaccines," and the results were exclusively studied to construct this review. WT1 vaccines work by introducing peptides from the WT1 protein to trigger an immune response involving cytotoxic T lymphocytes via antigen-presenting cells. Upon activation, these lymphocytes induce apoptosis in cancer cells by specifically targeting those with increased WT1 levels. WT1 vaccinations, which are usually given in addition to chemotherapy, have demonstrated clinically positive results and minimal side effects. However, there are several challenges to their widespread use, such as the immunosuppressive nature of tumors and heterogeneity in expression. Despite these limitations, the risk-benefit profile of cancer vaccines is encouraging, especially for the WT1 vaccine in the treatment of advanced pancreatic cancer. Considering the fledgling status of their development, large multicentric, variables-matched, extensive analysis across diverse demographics is considered essential.

Advancements in dendritic cell vaccination: enhancing efficacy and optimizing combinatorial strategies for the treatment of glioblastoma

Glioblastomas (GBM) are highly invasive, malignant primary brain tumors. The overall prognosis is poor, and management of GBMs remains a formidable challenge, necessitating novel therapeutic strategies such as dendritic cell vaccinations (DCVs). While many early clinical trials demonstrate an induction of an antitumoral immune response, outcomes are mixed and dependent on numerous factors that vary between trials. Optimization of DCVs is essential; the selection of GBM-specific antigens and the utilization of 18F-fludeoxyglucose Positron Emission Tomography (FDG-PET) may add significant value and ultimately improve outcomes for patients undergoing treatment for glioblastoma. This review provides an overview of the mechanism of DCV, assesses previous clinical trials, and discusses future strategies for the integration of DCV into glioblastoma treatment protocols. To conclude, the review discusses challenges associated with the use of DCVs and highlights the potential of integrating DCV with standard therapies.

Cytotoxic CD4+ T cells in chronic viral infections and cancer

CD4+ T cells play an important role in immune responses against pathogens and cancer cells. Although their main task is to provide help to other effector immune cells, a growing number of infections and cancer entities have been described in which CD4+ T cells exhibit direct effector functions against infected or transformed cells. The most important cell type in this context are cytotoxic CD4+ T cells (CD4+ CTL). In infectious diseases anti-viral CD4+ CTL are mainly found in chronic viral infections. Here, they often compensate for incomplete or exhausted CD8+ CTL responses. The induction of CD4+ CTL is counter-regulated by Tregs, most likely because they can be dangerous inducers of immunopathology. In viral infections, CD4+ CTL often kill via the Fas/FasL pathway, but they can also facilitate the exocytosis pathway of killing. Thus, they are very important effectors to keep persistent virus in check and guarantee host survival. In contrast to viral infections CD4+ CTL attracted attention as direct anti-tumor effectors in solid cancers only recently. Anti-tumor CD4+ CTL are defined by the expression of cytolytic markers and have been detected within the lymphocyte infiltrates of different human cancers. They kill tumor cells in an antigen-specific MHC class II-restricted manner not only by cytolysis but also by release of IFNγ. Thus, CD4+ CTL are interesting tools for cure approaches in chronic viral infections and cancer, but their potential to induce immunopathology has to be carefully taken into consideration.

MHCII Expression on Peripheral Blood Monocytes in Canine Lymphoma: An Impact of Glucocorticoids

Simple Summary

Loss or decreased expression of human leukocyte antigen—D-related (HLA-DR) on the surface of monocytes is related to the dysfunction of the immune system and was reported in human neoplasia, including lymphoma. Canine lymphoma is frequently presented as a valuable comparative model for studies on human non-Hodgkin’s lymphoma. However, there are no studies on the expression of analogue proteins—MHCII antigens—on monocytes in canine lymphoma. In this study, we have evaluated the changes in the expression of MHCII on monocytes in the blood of dogs with lymphoma before any treatment and in dogs that had previously received glucocorticoids. Glucocorticoids are often used by clinicians as first drugs after diagnosis for immediate health improvement and are known to impact monocyte number. We have shown an increase in the percentage of MHCII− monocytes, regardless of treatment. However, only in dogs that had received glucocorticoids were changes in the proportion of MHCII+ and MHCII− monocytes reflected also by the changes in the number of MHCII− monocytes in the blood, which was significantly higher. Evaluating the changes in canine monocytes might be helpful in the diagnosis of various tumor types, monitoring of the treatment or assessing the immune status of dogs.

Abstract

An increase in the percentage of monocytes with reduced HLA-DR expression and immunosuppressive properties has been reported in numerous human neoplastic diseases, including lymphoma. However, there are no analogous studies on phenotypical variations in the peripheral blood monocytes in dogs with lymphoma. The aim of this study was to determine the difference in the expression of the MHCII molecule on peripheral blood monocytes in dogs with lymphoma before any treatment (NRG) and in dogs that had previously received glucocorticoids (RG) in comparison to healthy dogs. Flow cytometry immunophenotyping of peripheral blood leukocytes was performed using canine-specific or cross-reactive antibodies against CD11b, CD14 and MHCII. In the blood of dogs with lymphoma (NRG and RG), compared to that of healthy ones, the MHCII+ and MHCII− monocytes ratio was changed due to an increase in the percentage of MHCII− monocytes. The number of MHCII− monocytes was significantly higher only in RG dogs compared to healthy ones, which might result from the release of these cells from the blood marginal pool due to the action of glucocorticoids. Our results encourage further studies to assess if changes in MHCII expression affect immune status in dogs with lymphoma.

The Era of Cytotoxic CD4 T Cells

In 1986, Mosmann and Coffman identified 2 functionally distinct subsets of activated CD4 T cells, Th1 and Th2 cells, being key in distinct T cell mediated responses. Over the past three decades, our understanding of CD4 T cell differentiation has expanded and the initial paradigm of a dichotomic CD4 T cell family has been revisited to accommodate a constantly growing number of functionally distinct CD4 T helper and regulatory subpopulations. Of note, CD4 T cells with cytotoxic functions have also been described, initially in viral infections, autoimmune disorders and more recently also in cancer settings. Here, we provide an historical overview on the discovery and characterization of cytotoxic CD4 T cells, followed by a description of their mechanisms of cytotoxicity. We emphasize the relevance of these cells in disease conditions, particularly in cancer, and we provide insights on how to exploit these cells in immunotherapy.

Roles of CD4+ T cells as mediators of antitumor immunity

It has been well established that CD8+ T cells serve as effector cells of the adaptive immune response against tumors, whereas CD4+ T cells either help or suppress the generation of CD8+ cytotoxic T cells. However, in several experimental models as well as in cancer patients, it has been shown that CD4+ T cells can also mediate antitumor immunity either directly by killing tumor cells or indirectly by activating innate immune cells or by reducing tumor angiogenesis. In this review, we discuss the growing evidence of this underappreciated role of CD4+ T cells as mediators of antitumor immunity.

Targeting Immune Cells in the Tumor Microenvironment of HCC: New Opportunities and Challenges

Immune associated cells in the microenvironment have a significant impact on the development and progression of hepatocellular carcinoma (HCC) and have received more and more attention. Different types of immune-associated cells play different roles, including promoting/inhibiting HCC and several different types that are controversial. It is well known that immune escape of HCC has become a difficult problem in tumor therapy. Therefore, in recent years, a large number of studies have focused on the immune microenvironment of HCC, explored many mechanisms worth identifying tumor immunosuppression, and developed a variety of immunotherapy methods as targets, laying the foundation for the final victory in the fight against HCC. This paper reviews recent studies on the immune microenvironment of HCC that are more reliable and important, and provides a more comprehensive view of the investigation of the immune microenvironment of HCC and the development of more immunotherapeutic approaches based on the relevant summaries of different immune cells.

Role of Immune Cells in Patients with Hepatitis B Virus-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) develops almost entirely in the presence of chronic inflammation. Chronic hepatitis B virus (HBV) infection with recurrent immune-mediated liver damage ultimately leads to cirrhosis and HCC. It is widely accepted that HBV infection induces the dysfunction of the innate and adaptive immune responses that engage various immune cells. Natural killer (NK) cells are associated with early antiviral and antitumor properties. On the other hand, inflammatory cells release various cytokines and chemokines that may promote HCC tumorigenesis. Moreover, immunosuppressive cells such as regulatory T cells (Treg) and myeloid-derived suppressive cells play a critical role in hepatocarcinogenesis. HBV-specific CD8+ T cells have been identified as pivotal players in antiviral responses, whilst extremely activated CD8+ T cells induce enormous inflammatory responses, and chronic inflammation can facilitate hepatocarcinogenesis. Controlling and maintaining the balance in the immune system is an important aspect in the management of HBV-related HCC. We conducted a review of the current knowledge on the immunopathogenesis of HBV-induced inflammation and the role of such immune activation in the tumorigenesis of HCC based on the recent studies on innate and adaptive immune cell dysfunction in HBV-related HCC.

The Ancient Chinese Decoction Yu-Ping-Feng Suppresses Orthotopic Lewis Lung Cancer Tumor Growth Through Increasing M1 Macrophage Polarization and CD4+ T Cell Cytotoxicity

Background: The tumor microenvironment (TME) has a deep influence on cancer progression and has become into a new target for cancer treatment. In our previous study, we found that Yu-Ping-Feng (YPF), an ancient Chinese herbal decoction, significantly inhibited the Lewis lung cancer (LLC) tumor growth in a subcutaneous xenograft tumor model, and prolonged the survival of tumor-bearing mice. But the regulation of Yu-Ping-Feng on tumor microenvironment is unknown.

Methods: To access the effect of Yu-Ping-Feng on non-small cell lung cancer, an orthotopic luciferase stably expressed Lewis lung cancer tumor model was established on C57BL/6 mice, and then the survival and the tumor growth were evaluated. To address the tumor microenvironment immune regulation, the percentages of CD4⁺ T cells, CD8⁺ T cells, natural killer cells (NK), regulatory T cells (Treg), macrophages, and myeloid-derived suppressor cells (MDSC) in spleens and tumor tissues, the macrophage polarization and CD4⁺ T cell cytotocixity were analyzed by flow cytometry, biophotonic cell killing activity assay, real-time PCR and western-blot.

Results: Yu-Ping-Feng significantly prolonged orthotopic lung tumor-bearing mouse survival, and increased the percentages of CD4⁺ T cell and M1 macrophages and the cytotoxicity of CD4⁺ T cells. Yu-Ping-Feng significantly enhanced macrophage-mediated lysis of LLC in a concentration-dependent manner, and had no effect on CD4⁺ T cell-mediated lysis of LLC, but significantly increased CD4⁺ T cell-mediated lysis after co-incubated with macrophages. In addition, Yu-Ping-Feng induced M1 macrophage polarization through promoting the phosphorylation of STAT1.

Conclusion: Yu-Ping-Feng induced M1 macrophages polarization, and then activated CD4⁺ T lymphocytes, resulting in killing of LLC cells. Yu-Ping-Feng was a potent regulator of M1 macrophage polarization and might have a promising application in tumor immunotherapy.

Reduction of myeloid-derived suppressor cells reinforces the anti-solid tumor effect of recipient leukocyte infusion in murine neuroblastoma-bearing allogeneic bone marrow chimeras

Allogeneic hematopoietic stem cell transplantation is an emerging treatment option for solid tumors because of its capacity to elicit immune graft-versus-tumor effects. However, these are often limited and associated with GvHD. Adoptive recipient leukocyte infusion (RLI) was shown to enhance anti-tumor responses of allogeneic bone marrow transplantation in murine neuroblastoma (Neuro2A)-bearing chimeras. In contrast to the clinically used donor leukocyte infusion, the RLI anti-tumor effect-elicited by host-versus-graft lymphohematopoietic reactivity-does not cause GvHD; however, the tumor growth-inhibitory effect is incomplete, because overall survival is not prolonged. Here, we studied the anti-solid tumor mechanisms of RLI with the objective to improve its efficacy. Host-versus-graft reactivity following RLI was associated with a systemic cytokine storm, lymph node DC activation, and systemic expansion of host-derived IFN-γ-expressing CD4+ T cells and IFN-γ-and granzyme B-expressing CD8+ T cells, which acquired killing activity against Neuro2A and third-party tumor cells. The tumor showed up-regulation of MHC class I and a transient accumulation of IFN-γ-and granzyme B-expressing CD8+ T cells: the intra-tumor decline in cytotoxic CD8+ T cells coincided with a systemic-and to a lesser extent intra-tumoral-expansion of MDSC. In vivo MDSC depletion with 5-FU significantly improved the local tumor growth-inhibitory effect of RLI as well as overall survival. In conclusion, the RLI-induced alloreactivity gives rise to a host-derived cytotoxic T-cell anti-neuroblastoma response, but also drives an expansion of host-type MDSC that counteracts the anti-tumor effect. This finding identifies MDSC as a novel target to increase the effectiveness of RLI, and possibly other cancer immunotherapies.

Exosomes from heat-stressed tumour cells inhibit tumour growth by converting regulatory T cells to Th17 cells via IL-6

Exosomes derived from heat-stressed tumour cells (HS-TEXs), which contain abundant heat shock protein (HSP) 70, strongly induce antitumour immune responses. HSP70-induced interleukin (IL)-6 promotes IL-17 expression and causes rejection of established prostate tumours. However, it remains unclear whether HS-TEXs exhibit antitumour effects by converting regulatory T cells (T_regs ) into T helper type 17 (Th17) cells. In this study, we found that compared with TEXs, HS-TEXs were more potent in stimulating secretion of IL-6 from dendritic cells. In vitro, IL-6 blocked tumour cell-derived transforming growth factor beta 1-induced T_reg differentiation and promoted Th17 cell differentiation. HS-TEXs exerted strong antitumour effects, converting T_regs into Th17 cells with high efficiency, a process that was entirely dependent upon IL-6. Neutralization of IL-17 completely abolished the antitumour effect of TEXs, but only partially inhibited that of HS-TEXs. In addition, we found higher levels of IL-6 and IL-17 in serum from tumour patients treated with hyperthermia, and an increase in Th17 cells and a decrease in T_regs was detected in peripheral blood mononuclear cells isolated from these patients after hyperthermia. Therefore, our results demonstrate that HS-TEXs possess a powerful capacity to convert immunosuppressive T_regs into Th17 cells via IL-6, which contributes to their potent antitumour effect.

Adoptive cell therapy with CD4+ T helper 1 cells and CD8+ cytotoxic T cells enhances complete rejection of an established tumour, leading to generation of endogenous memory responses to non-targeted tumour epitopes

The results of adoptive T-cell therapies (ACTs) are very encouraging and show clinical evidence that ACT can provide a cure for patients with metastatic disease. However, various response rates and long-term cancer remission have been observed in different ACT trials. The types of T cells, prior treatment with chemotherapy and co-administration of other immune-target therapies have been found to influence the efficacy of ACT. In this study, we investigate the ability of ACT using CD4⁺ T helper 1 (Th1) cells and CD8⁺ cytotoxic T lymphocytes (CTLs) to reject the growth of established B16-ovalbumin (OVA) melanoma. CD8⁺ CTLs were found to be the main effector T cells that mediated tumour regression. However, low tumour-free survival rates were observed in ACT with CD8⁺ CTLs only. Co-transferring CD4⁺ Th1 cells and CD8⁺ CTLs has been observed to induce a synergistic antitumour response, resulting in complete regression in 80% of the tumour-bearing mice. We also examined a prior Dacarbazine (DTIC) and after virus-like particle (VLP)-OVA vaccine treatment to enhance ACT, but no therapeutic benefit was observed during primary B16-OVA tumour growth. Nevertheless, the ACT-mediated antitumour response was able to generate memory responses to both B16-OVA and B16-gp33 tumours. VLP-OVA vaccination following ACT enhances the memory responses to tumours that express a heterogenic population of both B16-OVA and B16-gp33 cells; however, it abolished the memory response to tumours consisting of only gp33-expressing cells. These findings provide important information for designing therapeutic treatments for patients with metastatic disease and cancer relapse to achieve durable cancer remission.

Fighting Viral Infections and Virus-Driven Tumors with Cytotoxic CD4+ T Cells

CD4+ T cells have been and are still largely regarded as the orchestrators of immune responses, being able to differentiate into distinct T helper cell populations based on differentiation signals, transcription factor expression, cytokine secretion, and specific functions. Nonetheless, a growing body of evidence indicates that CD4+ T cells can also exert a direct effector activity, which depends on intrinsic cytotoxic properties acquired and carried out along with the evolution of several pathogenic infections. The relevant role of CD4+ T cell lytic features in the control of such infectious conditions also leads to their exploitation as a new immunotherapeutic approach. This review aims at summarizing currently available data about functional and therapeutic relevance of cytotoxic CD4+ T cells in the context of viral infections and virus-driven tumors.

Circulating CXCR5+CD4+ T cells assist in the survival and growth of primary diffuse large B cell lymphoma cells through interleukin 10 pathway

Diffuse large B cell lymphoma (DLBCL) is a common and aggressive cancer caused by the malignant transformation of B cells. Although it has been established that the follicular helper T (Tfh) cells play a central role in B cell development, little information is available on their involvement in DLBCL pathogenesis. We studied the role of the peripheral Tfh equivalent, the CXCR5⁺ CD4⁺ T cells, in DLBCL. Data showed that compared to CXCR5^- CD4⁺ T cells, CXCR5⁺ CD4⁺ T cells were significantly more effective at promoting the proliferation as well as inhibiting the apoptosis of primary autologous DLBCL tumor cells. Surprisingly, we found that at equal cell numbers, CXCR5⁺ CD4⁺ T cells in DLBCL patients secreted significantly less interleukin (IL)-21 than CXCR5^- CD4⁺ T cells, while the level of IL-10 secretion was significant elevated in the CXCR5⁺ compartment compared to the CXCR5^- compartment. Neutralization of IL-10 in the primary DLBCL-CXCR5⁺ CD4⁺ T cell coculture compromised the CXCR5⁺ CD4⁺ T cell-mediated pro-tumor effects, in a manner that was dependent on the concentration of anti-IL-10 antibodies. The CXCR5⁺ compartment also contained significantly lower frequencies of cytotoxic CD4⁺ T cells than the CXCR5^- compartment. In conclusion, our investigations discovered a previously unknown pro-tumor role of CXCR5-expressing circulating CD4⁺ T cells, which assisted the survival and proliferation of primary DLBCL cells through IL-10.

Conditions for the generation of cytotoxic CD4(+) Th cells that enhance CD8(+) CTL-mediated tumor regression

Adoptive cell therapies (ACTs) using tumor-reactive T cells have shown clinical benefit and potential for cancer treatment. While the majority of the current ACT are focused on using CD8⁺ cytotoxic T lymphocytes (CTL), others have shown that the presence of tumor-reactive CD4⁺ T helper (Th) cells can greatly enhance the anti-tumor activity of CD8⁺ CTL. However, difficulties in obtaining adequate numbers of CD4⁺ Th cells through in vitro expansion can limit the application of CD4 Th cells in ACT. This study aims to optimize the culture conditions for mouse CD4 T cells to provide basic information for animal studies of ACT using CD4 T cells. Taking advantage of the antigen-specificity of CD4⁺ Th cells from OT-II transgenic mice, we examined different methodologies for generating antigen-specific CD4⁺ Th1 cells in vitro. We found that cells grown in complete advanced-DMEM/F12 medium supplemented with low-dose IL-2 and IL-7 induced substantial cell expansion. These Th cells were Th1-like, as they expressed multiple Th1-cytokines and exhibited antigen-specific cytotoxicity. In addition co-transfer of these CD4⁺ Th1-like cells with CD8⁺ CTL significantly enhanced tumor regression, leading to complete cure in 80% of mice bearing established B16-OVA. These observations indicate that the CD4⁺ Th1-like cells generated using the method we optimized are functionally active to eliminate their target cells, and can also assist CD8⁺ CTL to enhance tumor regression. The findings of this study provide valuable data for further research into in vitro expansion of CD4⁺ Th1-like cells, with potential applications to cancer treatment involving ACT.

Induction of CD4(+) and CD8(+) anti-tumor effector T cell responses by bacteria mediated tumor therapy

Facultative anaerobic bacteria like E. coli can colonize solid tumors often resulting in tumor growth retardation or even clearance. Little mechanistic knowledge is available for this phenomenon which is however crucial for optimization and further implementation in the clinic. Here, we show that intravenous injections with E. coli TOP10 can induce clearance of CT26 tumors in BALB/c mice. Importantly, re-challenging mice which had cleared tumors showed that clearance was due to a specific immune reaction. Accordingly, lymphopenic mice never showed tumor clearance after infection. Depletion experiments revealed that during induction phase, CD8(+) T cells are the sole effectors responsible for tumor clearance while in the memory phase CD8(+) and CD4(+) T cells were involved. This was confirmed by adoptive transfer. CD4(+) and CD8(+) T cells could reject newly set tumors while CD8(+) T cells could even reject established tumors. Detailed analysis of adoptively transferred CD4(+) T cells during tumor challenge revealed expression of granzyme B, FasL, TNF-α and IFN-γ in such T cells that might be involved in the anti-tumor activity. Our findings should pave the way for further optimization steps of this promising therapy.

Immunotherapy for hepatocellular carcinoma: From basic research to clinical use

Hepatocellular carcinoma (HCC) is a common cancer worldwide with a poor prognosis. Few strategies have been proven efficient in HCC treatment, particularly for those patients not indicated for curative resection or transplantation. Immunotherapy has been developed for decades for cancer control and is attaining more attention as a result of encouraging outcomes of new strategies such as chimeric antigen receptor T cells and immune checkpoint blockade. Right at the front of the new era of immunotherapy, we review the immunotherapy in HCC treatment, from basic research to clinical trials, covering anything from immunomodulators, tumor vaccines and adoptive immunotherapy. The mechanisms, efficacy and safety as well as the approach particulars are unveiled to assist readers to gain a concise but extensive understanding of immunotherapy of HCC.

Vaccination with vascular progenitor cells derived from induced pluripotent stem cells elicits antitumor immunity targeting vascular and tumor cells

Vaccination of BALB/c mice with dendritic cells (DCs) loaded with the lysate of induced vascular progenitor (iVP) cells derived from murine-induced pluripotent stem (iPS) cells significantly suppressed the tumor of CMS-4 fibrosarcomas and prolonged the survival of CMS-4-inoculated mice. This prophylactic antitumor activity was more potent than that of immunization with DCs loaded with iPS cells or CMS-4 tumor cells. Tumors developed slowly in mice vaccinated with DCs loaded with iVP cells (DC/iVP) and exhibited a limited vascular bed. Immunohistochemistry and a tomato-lectin perfusion study demonstrated that the tumors that developed in the iVP-immunized mice showed a marked decrease in tumor vasculature. Immunization with DC/iVP induced a potent suppressive effect on vascular-rich CMS-4 tumors, a weaker effect on BNL tumors with moderate vasculature, and nearly no effect on C26 tumors with poor vasculature. Treatment of DC/iVP-immunized mice with a monoclonal antibody against CD4 or CD8, but not anti-asialo GM1, inhibited the antitumor activity. CD8(+) T cells from DC/iVP-vaccinated mice showed significant cytotoxic activity against murine endothelial cells and CMS-4 cells, whereas CD8(+) T cells from DC/iPS-vaccinated mice did not. DNA microarray analysis showed that the products of 29 vasculature-associated genes shared between genes upregulated by differentiation from iPS cells into iVP cells and genes shared by iVP cells and isolated Flk-1(+) vascular cells in CMS-4 tumor tissue might be possible targets in the immune response. These results suggest that iVP cells from iPS cells could be used as a cancer vaccine targeting tumor vascular cells and tumor cells.

Improving immunotherapy of hepatocellular carcinoma (HCC) using dendritic cells (DC) engineered to express IL-12 in vivo

BACKGROUND

Interleukin 12 (IL-12), one of the most potent Th1-cytokines, has been used to improve dendritic cells (DC)-based immunotherapy of cancer. However, it failed to achieve clinical response in patients with hepatocellular carcinoma (HCC). In this study, improved conditions of immunotherapy with DC engineered to express IL-12 were studied in murine subcutaneous HCC.

METHODS

Tumour-lysate pulsed DC were transduced with IL-12-encoding adenoviruses or cultivated with recombinant (r)IL-12. DC were injected intratumourally, subcutaneously or intravenously at different stages of tumour-development.

RESULTS

Dendritic cell overexpressing IL-12 by adenoviruses showed enhanced expression of costimulatory molecules and stronger priming of HCC-specific effector cells than DC cultured with rIL-12. Intratumoural but not systemic injections of IL-12-DC induced the strongest antitumoural effects reaching complete regressions in 75% of early-staged tumours and in 33% of advanced tumours. Importantly, antitumoural effects could be further enhanced through combination with sorafenib. Analysing the tumour-environment, IL-12-DC increased the levels of Th1-cytokines/chemokines and of CD4(+) -, CD8(+) -T- and NK-cells. Induced immunity was tumour-specific and sustained since all tumour-free animals were protected towards hepatic tumour-cell rechallenge. However, IL-12-DC also enhanced immunosuppressive cytokines, regulatory T cells and even myeloid-derived suppressor cells within the tumours.

CONCLUSIONS

Induced IL-12-overexpression by adenoviral vectors can effectively immunostimulate DC. Intratumoural but not systemic injection of activated IL-12-DC was crucial for effective tumour regression. The mechanism of this approach seems to be the induction of a sufficient Th1 tumour-environment allowing the recruitment of effector cells rather than the inhibition of tumour immunosuppression. Thus, improved immunotherapy with IL-12-DC represents a promising approach towards HCC.

Impairment of CD4+ cytotoxic T cells predicts poor survival and high recurrence rates in patients with hepatocellular carcinoma

The role of CD4(+) cytotoxic T cells (CTLs) in hepatocellular carcinoma (HCC) remains obscure. This study characterized CD4(+) CTLs in HCC patients and further elucidated the associations between CD4(+) CTLs and HCC disease progression. In all, 547 HCC patients, 44 chronic hepatitis B (CHB) patients, 86 liver cirrhosis (LC) patients, and 88 healthy individuals were enrolled in the study. CD4(+) CTLs were defined by flow cytometry, immunohistochemistry, and lytic granule exocytosis assays. A multivariate analysis of prognostic factors for overall survival was performed using the Cox proportional hazards model. Circulating and liver-infiltrating CD4(+) CTLs were found to be significantly increased in HCC patients during early stage disease, but decreased in progressive stages of HCC. This loss of CD4(+) CTLs was significantly correlated with high mortality rates and reduced survival time of HCC patients. In addition, the proliferation, degranulation, and production of granzyme A, granzyme B, and perforin of CD4(+) CTLs were inhibited by the increased forkhead/winged helix transcription factor (FoxP3(+) ) regulatory T cells in these HCC patients. Further analysis showed that both circulating and tumor-infiltrating CD4(+) CTLs were independent predictors of disease-free survival and overall survival after the resection of the HCC.

CONCLUSION

The progressive deficit in CD4(+) CTLs induced by increased FoxP3(+) regulatory T cells was correlated with poor survival and high recurrence rates in HCC patients. These data suggest that CD4(+) CTLs may represent both a potential prognostic marker and a therapeutic target for the treatment of HCC.

Tumor-specific CD4+ T cells develop cytotoxic activity and eliminate virus-induced tumor cells in the absence of regulatory T cells

The important role of tumor-specific cytotoxic CD8⁺ T cells is well defined in the immune control of the tumors, but the role of effector CD4⁺ T cells is poorly understood. In the current research, we have used a murine retrovirus-induced tumor cell line of C57BL/6 mouse origin, namely FBL-3 cells, as a model to study basic mechanisms of immunological control and escape during tumor formation. This study shows that tumor-specific CD4⁺ T cells are able to protect against virus-induced tumor cells. We show here that there is an expansion of tumor-specific CD4⁺ T cells producing cytokines and cytotoxic molecule granzyme B (GzmB) in the early phase of tumor growth. Importantly, we demonstrate that in vivo depletion of regulatory T cells (Tregs) and CD8⁺ T cells in FBL-3-bearing DEREG transgenic mice augments IL-2 and GzmB production by CD4⁺ T cells and increases FV-specific CD4⁺ T-cell effector and cytotoxic responses leading to the complete tumor regression. Therefore, the capacity to reject tumor acquired by tumor-reactive CD4⁺ T cells largely depends on the direct suppressive activity of Tregs. We suggest that a cytotoxic CD4⁺ T-cell immune response may be induced to enhance resistance against oncovirus-associated tumors.

CD4 T cell dependent tumor immunity stimulated by dendritic cell based vaccine

CD8 CTLs have been accountable for the major effector cells responsible for the rejection of tumor cells. And CD40 signaling and IL-12 have been shown to be the essential pathways involved in the activation process. Immunizing mice with dendritic cells transduced with an adenovirus expressing the human melanoma antigen gp 100, an immunization strategy of xenoimmunization, stimulated potent tumor protection dependent on effective CD4 T cells in the absence of CD8 T cells. Further studies revealed that neither CD40 signaling nor IL-12 was indispensable for the activation of dendritic and CD4 T cells in this model. Stimulation of effective antitumor immunity targeting the self-antigen did not elicit autoimmunity. The implications of this study were discussed.

Expansion of interferon-gamma-producing multifunctional CD4+ T-cells and dysfunctional CD8+ T-cells by glypican-3 peptide library in hepatocellular carcinoma patients

Glypican-3 is a promising target for immunotherapy for hepatocellular carcinoma, but limited data exist regarding its immunogenicity in patients with diverse HLA types, immunogenicity for CD4(+) T-cells, and the impact of inhibitory co-stimulation on glypican-3-specific T-cells. Using a 15mer overlapping peptide library for glypican-3, PBMC from patients with HCC were assessed ex vivo and after short-term in vitro expansion for tumor antigen-specific T-cell responses with and without blockade of PD-1/PD-L1 and CTLA-4 signaling. Glypican-3-specific T-cells were undetectable ex vivo, but primarily IFNγ(+)TNFα(+) CD4(+) T-cells expanded with short-term in vitro stimulation in 10/19 (52%) patients. Glypican-3-specific CD8(+) T-cells predominantly produced TNFα, but did not secrete IFNγ nor degranulate. CTLA-4 and PD-1 blockade minimally impacted the cytokine secretion and proliferation of glypican-3-specific T-cells. These data suggest that CD8(+) T-cell-directed tumor vaccines in HCC may have limited potential for efficacy unless optimal co-stimulation conditions can be identified but CD4(+)-directed vaccines merit consideration.

Dramatic efficacy improvement of a DC-based vaccine against AML by CD25 T cell depletion allowing the induction of a long-lasting T cell response

Dendritic cell (DC)-based vaccination is a promising approach to enhance anti-tumor immunity that could be considered for acute myeloid leukemia (AML) patients with high-risk of relapse. Our purpose was to study the efficiency and to optimize the immunogenicity of a DC-based vaccine in a preclinical AML murine model. In this report, C57BL6 mice were vaccinated with DC pulsed with peptides eluted (EP) from the syngeneic C1498 myelomonocytic leukemic cell line in a prophylactic setting. In this model, a natural antileukemic immunity mediated by NK cells was observed in the control unloaded DC-vaccinated group. On the other hand, we showed that the cytotoxic antileukemic immune response induced by vaccination with eluted peptides pulsed-DC (DC/EP), in vitro and in vivo, was mainly mediated by CD4(+) T cells. Treatment with anti-CD25 antibody to deplete CD4(+) CD25(+) regulatory T cells before DC-vaccination dramatically improved the antileukemic immune response induced by immunization, and allowed the development of long-lasting immune responses that were tumor protective after a re-challenge with leukemic cells. Our results suggest that this approach could be successful against weakly immunogenic tumors such as AML, and could be translated in human.

A phase 1/2 study of autologous neuroblastoma tumor cells genetically modified to secrete IL-2 in patients with high-risk neuroblastoma

Autologous neuroblastoma (NB) tumor cells modified to secrete interleukin (IL)-2 (auto-IL-2) can be safely given to patients with advanced neuroblastoma and generate antitumor immune responses. As the benefits of tumor immunization may be greater in patients with minimal residual disease and thus rely on surrogate markers such as immune responses to measure effect, we studied the frequency of immune changes associated with vaccination. Thirteen patients (8 in first remission and 5 after treatment for recurrent NB) received 5 to 8 subcutaneous injections of auto-IL-2 at 0.3 x 10 cells/kg. The vaccine was well tolerated. Injection site biopsies revealed increased cellularity caused by infiltration of CD4 and CD8 lymphocytes, eosinophils, and dendritic cells. Enzyme-linked immunosorbent spot assays for interferon-gamma and IL-5 demonstrated that vaccination produced a rise in circulating CD4 and CD8 T cells responsive to stimulation by autologous tumor cells. Median event-free survival was 22 months for patients in first remission and 3 months for all others. Four patients treated in first remission remain alive and 3 without disease recurrence.

Effect of gonadectomy on HCC development in HBV transgenic mice

BACKGROUND AND AIMS

Epidemiological data demonstrate that HCC is prevalent in men compared to women. Herein, we examined the effect of gonadectomy in a murine model that spontaneously develops HCC.

ANIMALS AND METHODS

Thirty-two male and 26 female HBV transgenic mice [Tg (Alb-1 HBV) Bri 44] underwent surgical castration or sham operation. At the 18th month, serum samples were collected and all mice were sacrificed. Liver weight and volume were evaluated, each liver was cut into 1.5-mm-thick consecutive slices and nodules were examined on freshly isolated tissue. Consecutive histological sections obtained from each liver slice were evaluated to confirm the diagnosis of HCC.

RESULTS

Sham-operated females showed a significantly lower neoplastic growth compared to sham-operated males. This difference disappeared when females underwent gonadectomy. In males, neoplastic growth was not influenced by gonadectomy. Testosterone and estradiol levels were profoundly modified by gonadectomy in both males and females. The testosterone/estradiol ratio in gonadectomized females increased 4.5-fold compared to that in sham-operated females, becoming more similar to the ratio observed in castrated and sham-operated male mice.

CONCLUSIONS

HCC growth in our experimental model was not simply influenced by the levels of testosterone or estradiol, taken singularly, but depended on their ratio.

In vivo effects of cytokines on pancreatic beta-cells in models of type I diabetes dependent on CD4(+) T lymphocytes

CD4(+) T cells can actively kill beta-cells in type I diabetes as well as help CD8(+) T cells become cytolytic. Cytokines have the potential to kill beta-cells, or upregulate Fas on beta-cells, and increase their susceptibility to FasL. We investigated the direct effects of cytokines on beta-cells in perforin-deficient non-obese diabetic (NOD) mice and NOD4.1 TCR transgenic mice, two models in which CD8(+) T cells play a less dominant role. Inhibiting the effects of cytokines by the overexpression of suppressor of cytokine signalling-1 (SOCS1) in beta-cells did not reduce diabetes or insulitis in perforin-deficient NOD, NOD4.1 or interleukin (IL)-1 receptor-deficient NOD4.1 mice. SOCS1 overexpression prevented Fas upregulation on NOD4.1 beta-cells, but did not prevent islet destruction because SOCS1 transgenic islets were killed when grafted into NOD4.1.scid mice. Likewise, Fas-deficient NOD.lpr islets were destroyed in NOD4.1 mice. Although blocking the effects of interferon (IFN)gamma on beta-cells did not affect diabetes in NOD4.1 mice, global deficiency of IFNgammaR2 reduced diabetes and insulitis, suggesting that IFNgamma is involved in CD4(+) T-cell activation or migration. Our data show that beta-cells under attack by CD4(+) T cells are not destroyed by the effects of cytokines including IFNgamma and IL-1 or Fas-dependent cytotoxicity.

Advances in tumour immunotherapy

The clinical goal of tumour immunotherapy is to provide either active or passive immunity against malignancies by harnessing the immune system to target tumours. Although vaccination is an effective strategy to prevent infectious disease, it is less effective in the therapeutic setting for cancer treatment, which might be related to the low immunogenicity of tumour antigens and the reduced immunocompetence of cancer patients. Recent advances in technology have led to the development of passive immunotherapy approaches that utilize the unique specificity of antibodies and T cell receptors to target selected antigens on tumour cells. These approaches are likely to benefit patients and alter the way that clinicians treat malignant disease. In this article we review recent advances in the immunotherapy of cancer, focusing on new strategies to enhance the efficacy of passive immunotherapy with monoclonal antibodies and antigen-specific T cells.

The co-translocation of ERp57 and calreticulin determines the immunogenicity of cell death

The exposure of calreticulin (CRT) on the plasma membrane can precede anthracycline-induced apoptosis and is required for cell death to be perceived as immunogenic. Mass spectroscopy, immunofluorescence and immunoprecipitation experiments revealed that CRT co-translocates to the surface with another endoplasmic reticulum-sessile protein, the disulfide isomerase ERp57. The knockout and knockdown of CRT or ERp57 inhibited the anthracycline-induced translocation of ERp57 or CRT, respectively. CRT point mutants that fail to interact with ERp57 were unable to restore ERp57 translocation upon transfection into crt(-/-) cells, underscoring that a direct interaction between CRT and ERp57 is strictly required for their co-translocation to the surface. ERp57(low) tumor cells generated by retroviral introduction of an ERp57-specific shRNA exhibited a normal apoptotic response to anthracyclines in vitro, yet were resistant to anthracycline treatment in vivo. Moreover, ERp57(low) cancer cells (which failed to expose CRT) treated with anthracyclines were unable to elicit an anti-tumor response in conditions in which control cells were highly immunogenic. The failure of ERp57(low) cells to elicit immune responses and to respond to chemotherapy could be overcome by exogenous supply of recombinant CRT protein. These results indicate that tumors that possess an intrinsic defect in the CRT-translocating machinery become resistant to anthracycline chemotherapy due to their incapacity to elicit an anti-cancer immune response.

CD40ligand-expressing dendritic cells induce regression of hepatocellular carcinoma by activating innate and acquired immunity in vivo

Dendritic cells (DCs) are professional antigen-presenting cells able to prime T-cells against tumor-associated antigens (TAA), but their potential to induce hepatocellular carcinoma (HCC) regression is still limited. CD40/CD40L interaction is essential for DC activation and induction of antigen-specific T-cells. In this study, transduction of TAA-pulsed DC with a CD40L-encoding adenovirus (Ad-CD40L) was used to improve the immune response induced by DC toward HCC. Bone marrow-derived DC from C3H/HeNcrl mice were cultured with granulocyte-macrophage colony-stimulating factor and interleukin-4. On day 6, tumor-lysate pulsed DCs were infected with adenoviruses. HCCs were induced by inoculation of mice with Hepa129-cells subcutaneously. When tumor-volume was 100 to 400 mm(3), DCs were injected intratumorally, subcutaneously, or intravenously. Ad-CD40L transduction exerted CD40/CD40L interactions between DCs, increasing DC immunostimulation with up-regulation of CD80/CD86- and interleukin-12 (IL-12) expression. Intratumoral injection of CD40L-DC was superior to intravenous or subcutaneous treatments, yielding tumor elimination in almost 70% of mice. Moreover, all tumor-free animals were protected against hepatic tumor cell rechallenge. In a preventive setting, subcutaneous injection of CD40L-expressing DCs protected 50% of mice for more than 3 months toward tumor cell challenge. The induced immune response seemed to be dependent on cross-priming with Th1-lymphocytes in the lymph nodes, because transduced DCs were redetected in lymphoid tissues. In addition, immunohistochemistry of tumors indicated a significant tumor infiltration with CD4+, CD8+ T cells and natural killer (NK) cells. Tumor-infiltrating lymphocytes were tumor-specific, as shown in interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot and T-cell proliferation assays.

CONCLUSION

Transduction of DCs with Ad-CD40L increases significantly the stimulatory capacity of DCs. Intratumoral injection of DCs activates both acquired and innate immunity, inducing complete regression of established tumors and long-term immunity against tumor recurrence. This approach improves the antitumoral potential of DCs.

Allogeneic MHC gene transfer enhances an effective antitumor immunity in the early period of autologous hematopoietic stem cell transplantation

PURPOSE

In autologous hematopoietic stem cell transplantation (HSCT), lymphopenia-induced homeostatic proliferation of T cells is driven by the recognition of self-antigens, and there is an opportunity to skew the T-cell repertoire during the T-cell recovery by engaging tumor-associated antigens, leading to a break of tolerance against tumors. However, the homeostatic proliferation-driven antitumor responses seem to decline rapidly in association with tumor growth. We hypothesized that a tumor-specific immune response induced by an immune gene therapy could enhance and sustain homeostatic proliferation-induced antitumor immunity.

EXPERIMENTAL DESIGN

The antitumor effect of allogeneic MHC (alloMHC) gene transfer was examined at the early phase of the immune reconstitution after syngeneic HSCT.

RESULTS

Syngeneic HSCT showed significant tumor growth inhibition of syngeneic colon cancer cells within a period of 30 days; however, the tumor then resumed rapid growth and the survival of the mice was not prolonged. In contrast, when the alloMHC plasmid was intratumorally injected at the early phase after syngeneic HSCT, the established tumors were markedly regressed and the survival of recipient mice was prolonged without significant toxicities, whereas no survival advantage was recognized in recipient mice injected with a control plasmid. This tumor suppression was evident even in the other tumors that were not injected with the alloMHC plasmid. The antitumor response was characterized by the development of tumor-specific T cell- and natural killer cell-mediated cytotoxicities.

CONCLUSION

The results suggest the efficacy and safety of integrating intratumoral alloMHC gene transfer with an autologous HSCT for the treatment of solid cancers.

CD4+ T-cell-dependent tumour rejection in an immune-privileged environment requires macrophages

Although intraocular tumours reside in an immune-privileged site, they can circumvent immune privilege and undergo rejection. Ocular tumour rejection typically follows one of two pathways. One pathway involves CD4+ T cells, delayed-type hypersensitivity (DTH), and culmination in ischemic necrosis of the tumour and phthisis (atrophy) of the eye. The second pathway is DTH-independent and does not inflict collateral injury to ocular tissues, and the eye is preserved. In this study, we used a well-characterized tumour, Ad5E1, to investigate the role of CD4+ T cells in the non-phthisical form of intraocular tumour rejection. It has been previously documented that CD4+ T cells and interferon (IFN)-gamma are necessary for rejection of these tumours in the eye. In this study, we demonstrate that CD4+ T cells can circumvent immune privilege and infiltrate intraocular Ad5E1 tumours. Following tumour rejection, CD4+ T cells from tumour rejector mice could be adoptively transferred to severe combined immunodeficiency (SCID) mice and protect them from intraocular Ad5E1 tumour growth. Tumour-specific CD4+ T cells produced IFN-gamma in response to Ad5E1 tumour antigens. Macrophages also contributed to rejection, as they were present in intraocular Ad5E1 tumours, and local depletion of macrophages resulted in progressive tumour growth. Ocular macrophages contributed to Ad5E1 tumour rejection, as Ad5E1 tumour rejection did not occur in macrophage-depleted SCID mice reconstituted with rejector CD4+ T cells. This demonstrates that macrophage and CD4+ T-cell co-operation is needed for non-phthisical rejection of intraocular tumours.

Mechanism of antitumor effect on mouse hepatocellular carcinoma by intratumoral injection of OK-432, a streptococcal preparation

Intratumoral (i.t.) injection of OK-432, a streptococcal preparation, into implanted tumors of mouse hepatocellular carcinoma (MIH-2) showed antitumor effect including tumor eradication. Intraperitoneal administration of same dose OK-432 did not exhibit tumor suppressive effect. In vitro cytotoxic test suggested that direct cytotoxic effect of OK-432 was not associated with antitumor activity by i.t.-OK-432 treatment. It was also found that Toll-like receptor 4 signaling was not involved in i.t.-OK-432 treatment. Three mice out of five, which had shown tumor eradication by i.t.-OK-432 treatment did not reject re-challenge of MIH-2 cells. Splenocytes from i.t.-OK-432 treated mice did not produce IFN-gamma by stimulation with MIH-2 cells in vitro, but produced abundant IFN-gamma by stimulation with OK-432. Immunofluorescence microscopy demonstrated that CD4+T cells, but not CD8+T cells, infiltrated to i.t.-OK-432 treated tumor tissue produced IFN-gamma. Tumor-infiltrating CD4+T cells from i.t.-OK-432 treated tumor tissue produced IFN-gamma by in vitro stimulation with OK-432 higher than those from untreated tumor tissue. IFN-gamma directly induced apoptosis of MIH-2 cells in vitro. Collectively, i.t.-OK-432 treatment induced priming of CD4+T cells to antigenecity of OK-432, and repetitive i.t.-OK-432 treatment induced IFN-gamma production from OK-432-sensitized CD4+T cells in tumor site, leading to apoptosis of MIH-2 cells susceptible to IFN-gamma.

Telomerase Activity in Tumor and Remnant Liver as Predictor of Recurrence and Survival in Hepatocellular Carcinoma after Resection

BACKGROUND AND AIM

Results after curative liver resection in hepatocellular carcinoma are unsatisfactory with regard to high postoperative intrahepatic recurrence and liver failure. This study evaluates telomerase activity in liver with and without tumor as a predictor of recurrence and survival.

MATERIALS AND METHODS

Liver tissue with and without tumor from 53 hepatocellular carcinoma patients receiving curative resection during the period of 1998-2000 was used for detecting telomerase activity by PCR-ELISA. Clinicopathological data were compared to identify predictors of recurrence and survival.

RESULTS

Telomerase activity was detected in 98% of liver tissue with tumor and 70% liver tissue without. Telomerase activity in cancerous liver correlated significantly with HCV infection (P = 0.012) and cirrhotic change in liver parenchyma (P = 0.006). Telomerase activity in non-cancerous liver correlated with high serum AFP level (P = 0.002). The telomerase activity of liver tissue with and without tumor is significant higher in patients with recurrence than in those without recurrence, 413.7 +/- 100.5 versus 110.8 +/- 32.7, P = 0.006, and 34.7 +/- 14.2 versus 4.2 +/- 1.4, P = 0.039. Recurrence could be predicted by abnormally high tumor telomerase activity (P = 0.026) or by advanced TNM stage (P = 0.001). TNM stage or high serum ALT level could predict multinodular intrahepatic recurrence (P = 0.028 and P = 0.030). High serum AFP combined with high telomerase activity in liver without tumor had a significant ability to predict poor survival (OR: 11.19, CI: 1.95-64.12, P = 0.007).

CONCLUSION

Tumor telomerase is an independent predictor of recurrence. Simultaneous high remnant liver telomerase and high serum AFP is a strong negative predictor of survival.

Interferon-gamma produced by interleukin-12-activated tumor infiltrating CD8+T cells directly induces apoptosis of mouse hepatocellular carcinoma

BACKGROUND/AIMS

Interleukin-12 (IL-12), a cytokine with antitumor activity, was examined for the suppressive effect on hepatocellular carcinoma (HCC) in mouse model, and its mechanism of antitumor activity was analyzed.

METHODS

Mice implanted with MIH-2 HCC cells were treated with recombinant mouse IL-12 (500 ng/mouse). Involvement of CD4(+), CD8(+), NK cells and interferon (IFN)-gamma on tumor suppression by IL-12 was examined by treatment of mice with each antibody. Interferon-gamma (IFN-gamma) production by tumor infiltrating cells was analyzed by immunofluorescence microscopy and flow cytometric analysis. Signal transduction for apoptosis induction was examined by immunoblot analysis.

RESULTS

The growth of implanted MIH-2 tumors was significantly suppressed by IL-12 and the suppression was inhibited by depletion of CD8(+)T cells. IL-12 treatment caused numerous IFN-gamma-producing CD8(+)T cells to infiltrate into MIH-2 tumors. Antitumor activity of IL-12 was blocked by treating mice with anti-IFN-gamma mAb. CD8(+)T cells from IL-12-treated mice attached to MIH-2 cells and produced IFN-gamma in vitro. Cell attachment might be associated with intercellular adhesion molecule-1 induced by IFN-gamma. In vitro treatment with IFN-gamma induced apoptosis of MIH-2 cells via a mitochondria-dependent pathway.

CONCLUSIONS

IL-12 suppressed HCC growth in mouse model. IFN-gamma produced by IL-12-activated tumor-infiltrating CD8(+)T cells directly induced apoptosis of HCC cells.

Glucocorticoid-induced TNF receptor family related gene activation overcomes tolerance/ignorance to melanoma differentiation antigens and enhances antitumor immunity

Glucocorticoid-induced TNF receptor family related protein (GITR) is present on many different cell types. Previous studies have shown that in vivo administration of an anti-GITR agonist mAb (DTA-1) inhibits regulatory T cells (Treg)-dependent suppression and enhances T cell responses. In this study, we show that administration of DTA-1 induces >85% tumor rejection in mice challenged with B16 melanoma. Rejection requires CD4+, CD8+, and NK1.1+ cells and is dependent on IFN-gamma and Fas ligand and independent of perforin. Depletion of Treg via anti-CD25 treatment does not induce B16 rejection, whereas 100% of the mice depleted of CD25+ cells and treated with DTA-1 reject tumors, indicating a predominant role of GITR on effector T cell costimulation rather than on Treg modulation. T cells isolated from DTA-1-treated mice challenged with B16 are specific against B16 and several melanoma differentiation Ags. These mice develop memory against B16, and a small proportion of them develop mild hypopigmentation. Consistent with previous studies showing that GITR stimulation increases Treg proliferation in vitro, we found in our model that GITR stimulation expanded the absolute number of FoxP3+ cells in vivo. Thus, we conclude that overall, GITR stimulation overcomes self-tolerance/ignorance and enhances T cell-mediated antitumor activity with minimal autoimmunity.

Cancer immunotherapy using dendritic/tumour-fusion vaccine induces elevation of serum anti-nuclear antibody with better clinical responses

Dendritic cell (DC) vaccines might induce both anti-tumour immunity and autoimmunity. In this report, we demonstrate elevated levels of anti-nuclear antibody (ANA) in the sera of patients with cancer who had received immunotherapy with a dendritic/tumour-fusion vaccine. Twenty-two patients were treated with DC vaccine of fusion cells composed of autologous DCs and tumour cells (DC/tumour-fusion vaccine), which was generated by treating each cell type with polyethylene glycol. Nine of the 22 patients were treated with both the DC/tumour-fusion vaccine and systemic administration of recombinant human interleukin (rhIL)-12. Serum levels of ANA were examined with an enzyme-linked immunosorbent assay kit. One patient with gastric carcinoma (patient 1, DC/tumour-fusion vaccine alone), one patient with breast cancer (patient 2, DC/tumour-fusion vaccine alone) and one patient with ovarian cancer (patient 3, DC/tumour-fusion vaccine + rhIL-12) showed significant elevations of serum ANA levels during treatment. In patient 1 malignant ascitic effusion resolved and serum levels of tumour markers decreased. Patients 2 and 3 remained in good physical condition during treatment for 24 and 9 months, respectively. Immunoblot analysis indicated antibody responses to autologous tumour cells after vaccination in patient 2. None of the treated patients showed clinical symptoms suggesting autoimmune disease. Patients with elevated serum levels of ANA had significantly longer treatment periods than those without it. Elevated serum levels of ANA after DC/tumour-fusion cell vaccine might be associated with anti-tumour immune response induced by the vaccination.