Human tumor antigens recognized by T-cells

Systematic analyses of the factors influencing sperm quality in patients with SARS-CoV-2 infection

To figure out how does SARS-CoV-2 affect sperm parameters and what influencing factors affect the recovery of sperm quality after infection? We conducted a prospective cohort study and initially included 122 men with SARS-CoV-2 infection. The longest time to track semen quality after infection is 112 days and 58 eligible patients were included in our study eventually. We subsequently exploited a linear mixed-effects model to statistically analyze their semen parameters at different time points before and after SARS-CoV-2 infection. Semen parameters were significantly reduced after SARS-CoV-2 infection, including total sperm count (211 [147; 347] to 167 [65.0; 258], P < 0.001), sperm concentration (69.0 [38.8; 97.0] to 51.0 [25.5; 71.5], P < 0.001), total sperm motility (57.5 [52.3; 65.0] to 51.0 [38.5; 56.8], P < 0.001), progressive motility (50.0 [46.2; 58.0] to 45.0 [31.5; 52.8], P < 0.001). The parameters displayed the greatest diminution within 30 days after SARS-CoV-2 infection, gradually recovered thereafter, and exhibited no significant difference after 90 days compared with prior to COVID-19 infection. In addition, the patients in the group with a low-grade fever showed a declining tendency in semen parameters, but not to a significant degree, whereas those men with a moderate or high fever produced a significant drop in the same parameters. Semen parameters were significantly reduced after SARS-CoV-2 infection, and fever severity during SARS-CoV-2 infection may constitute the main influencing factor in reducing semen parameters in patients after recovery, but the effect is reversible and the semen parameters gradually return to normal with the realization of a new spermatogenic cycle.

A phenotypic signature that identifies neoantigen-reactive T cells in fresh human lung cancers

A common theme across multiple successful immunotherapies for cancer is the recognition of tumor-specific mutations (neoantigens) by T cells. The rapid discovery of such antigen responses could lead to improved therapies through the adoptive transfer of T cells engineered to express neoantigen-reactive T cell receptors (TCRs). Here, through CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing) and TCR-seq of non-small cell lung cancer (NSCLC) tumor-infiltrating lymphocytes (TILs), we develop a neoantigen-reactive T cell signature based on clonotype frequency and CD39 protein and CXCL13 mRNA expression. Screening of TCRs selected by the signature allows us to identify neoantigen-reactive TCRs with a success rate of 45% for CD8+ and 66% for CD4+ T cells. Because of the small number of samples analyzed (4 patients), generalizability remains to be tested. However, this approach can enable the quick identification of neoantigen-reactive TCRs and expedite the engineering of personalized neoantigen-reactive T cells for therapy.

Immunotherapy in breast cancer: A clinician's perspective

Globally over 2 million women are diagnosed with breast cancer each year despite major advances in detection and treatment of the disease. Breast cancer is comprised of several distinct subtypes and understanding the heterogeneity of the disease has become crucial for treatment planning. Therapeutic strategies span from a hormone therapy-based focus for women with estrogen receptor positive breast cancer to targeting human epidermal growth factor (HER2) by small molecules, antibody-drug-conjugates (ADC) and monoclonal antibodies in those with HER2 overexpression. Other novel treatment strategies for select subgroups of patients include the cyclin-dependent kinase 4/6 (CDK4/6) inhibitors for women with estrogen receptor positive tumors, the poly ADP ribose polymerase (PARP) inhibitors for those with BRCA mutations, and phosphoinositide 3-kinase (PI3K) inhibitors for women with tumors harboring phophatidylinositol-4,5-bisphosphate 3 kinase catalytic subunit alpha (PIK3CA) mutations. In contrast, the treatment for women with triple negative breast cancer has until recently been solely limited to chemotherapy. The profound impact of immunotherapy on cancer treatment in general has created much hope for its potential in breast cancer. This review will focus on the current advances and the research of immunotherapy in breast cancer, particularly on immune checkpoint inhibitors, adoptive cell transfer and cancer vaccines.

Humoral immune responses: Unsung heroes of the war on cancer

Solid cancers progress from primordial lesions through complex interactions between tumor-promoting and anti-tumor immune cell types, ultimately leading to the orchestration of humoral and T cell adaptive immune responses, albeit in an immunosuppressive environment. B cells infiltrating most established tumors have been associated with a dual role: Some studies have associated antibodies produced by tumor-associated B cells with the promotion of regulatory activities on myeloid cells, and also with direct immunosuppression through the production of IL-10, IL-35 or TGF-β. In contrast, recent studies in multiple human malignancies identify B cell responses with delayed malignant progression and coordinated T cell protective responses. This includes the elusive role of Tertiary Lymphoid Structures identified in many human tumors, where the function of B cells remains unknown. Here, we discuss emerging data on the dual role of B cell responses in the pathophysiology of human cancer, providing a perspective on future directions and possible novel interventions to restore the coordinated action of both branches of the adaptive immune response, with the goal of maximizing immunotherapeutic effectiveness.

Cellular immunotherapy: a clinical state-of-the-art of a new paradigm for cancer treatment

Cancer immunotherapy has opened a new chapter in Medical Oncology. Many novel therapies are under clinical testing and some have already been approved and implemented in cancer treatment protocols. In particular, cellular immunotherapies take advantage of the antitumor capabilities of the immune system. From dendritic cell-based vaccines to treatments centered on genetically engineered T cells, this form of personalized cancer therapy has taken the field by storm. They commonly share the ex vivo genetic modification of the patient's immune cells to generate or induce tumor antigen-specific immune responses. The latest clinical trials and translational research have shed light on its clinical effectiveness as well as on the mechanisms behind targeting specific antigens or unique tumor alterations. This review gives an overview of the clinical developments in immune cell-based technologies predominantly for solid tumors and on how the latest discoveries are being incorporated within the standard of care.

Implications of T cell receptor biology on the development of new T cell therapies for cancer

Recently, two chimeric antigen receptor (CAR) T cell therapies were approved based on their remarkable efficacy in patients with hematological malignancies. By contrast, CAR-T cell therapies results in solid tumors have been less promising. To develop the next generation of T cell therapies a better understanding of T cell receptor (TCR) biology and its implication for the design of synthetic receptors is critical. Here, we review current and newly developed forms of T cell therapies and how their utilization of different components of the TCR signaling machinery and their requirement for engagement (or not) of human leukocyte antigen impacts their design, efficacy and applicability as cancer drugs. Notably, we highlight the development of human leukocyte antigen-independent T cell platforms that utilize the full TCR complex as having promise to overcome some of the limitations of existing T cell therapies.

＜Editors' Choice＞ Meddling with meddlers: curbing regulatory T cells and augmenting antitumor immunity

CD4⁺ regulatory T cells (Tregs) expressing the transcription factor forkhead box P3 (FoxP3) play an important role in self-tolerance and immune homeostasis. Tregs have evolved to protect the host from aberrant immune responses against self-components and collateral damages occurring in the process of defense against invading pathogens by softening immune responses. However, they turned to be a scourge in malignant tumors by not only allowing and promoting tumor growth but also suppressing effective antitumor actions, both inherent (host’s immune surveillance) and extrinsic (anticancer therapy). An increase in the number of Tregs infiltrating into tumor sites and a concomitant decrease in the number of CD8⁺ cytotoxic T lymphocytes are associated with a poor prognosis for various types of cancers, marking Tregs as notorious meddlers with an effective antitumor response. Various cancer immunotherapy approaches are often dampened by meddling Tregs, making them one of the major targets in the treatment of cancer. The recent success of immune checkpoint inhibitors (ICIs) that target immune checkpoint molecules expressed by Tregs or effector T cells implies, that “meddling with meddlers” represents an effective strategy in cancer immunotherapy. However, clinical responses to ICIs are effective and durable only in some patients with cancer, whereas more than half of them do not show significant clinical improvement. This implies that a therapeutic approach based on the use of a single ICI, or targeting Tregs alone, is insufficient, highlighting the need for combinatorial approaches. With regard to antitumor immune stimulation, several approaches, such as vaccination with peptides (or the corresponding DNA) to stimulate antigen-presenting CD8⁺ T cells with tumor-specific neoantigens, cancer/testis antigens, or cancer stem cell antigens, that eventually boost effective cytotoxic antitumor responses are being tested. This review describes the immunosuppressive physiology of Tregs and their meddling with the host’s antitumor immunity; current and prospective approaches to curb Tregs; and approaches to augment antitumor immunity.

Anti-tumor activity of human IgG1 anti-gp75 TA99 mAb against B16F10 melanoma in human FcgammaRI transgenic mice

Patients suffering from advanced melanoma have a very poor prognosis. Despite recent advances in the understanding of oncogenic mechanisms and therapeutic interventions, the median survival of patients with metastatic disease is less than 12 months. Immunotherapy of melanoma has been intensely investigated and holds great promises. Tyrosinase-related protein-1 or gp75 (TYRP-1/gp75) antigen is a melanosomal polypeptide. It is the most abundant glycoprotein synthesized by pigmented melanocytes and melanomas. It is specific for melanocytes and both primary and metastatic melanomas. In mice, administration of the mouse mAb anti-gp75 TA99 prevents outgrowth of B16F10 melanoma metastases. The activity of TA99 is dependent on the presence and activity of the IgG specific, Fc receptors. TA99 cross-reacts with human gp75, and is currently being used for diagnosis of patients. Here, we sequenced mIgG2a TA99 and found that the locus harboring the endogenous light chain of the fusion partner in the TA99 hybridoma cells is not inactivated, resulting in the production of a mixed pool of mAbs that mitigates binding to gp75. Since human IgG1 (hIgG1) is the most frequently used mAb format in clinical studies, we produced a recombinant hIgG1 TA99 molecule. Whereas it is known that hIgG1 can functionally interact with mouse Fc receptors, we found that hIgG1 TA99 did not exhibit in vivo activity against B16F10 melanoma in wild type C57BL/6 mice. However, results obtained in this study demonstrated anti-tumor activity of hIgG1 TA99 in FcγRIIB knockout mice and in human FcγRI transgenic mice. These results emphasize the need for testing hIgG mAb in mice with functional human FcγRs.

Regulatory T cells in cancer immunotherapy

FOXP3(+)CD25(+)CD4(+) regulatory T (Treg) cells, crucial for the maintenance of immunological self-tolerance, are abundant in tumors. Most of them are chemo-attracted to tumor tissues, expanding locally and differentiating into a Treg-cell subpopulation that strongly suppresses the activation and expansion of tumor-antigen-specific effector T cells. Several cancer immunotherapies targeting FOXP3(+)CD4(+) Treg cells, including depletion of Treg cells, are currently being tested in the clinic. In addition, clinical benefit of immune-checkpoint blockade, such as anti-CTLA-4 monoclonal antibody therapy, could be attributed at least in part to depletion of FOXP3(+)CD4(+) Treg cells from tumor tissues. Thus, optimal strategies need to be established for reducing Treg cells or attenuating their suppressive activity in tumor tissues, together with activating and expanding tumor-specific effector T cells.

Intratumoral injection of BCG-CWS-pretreated dendritic cells following tumor cryoablation

Intratumoral administration of dendritic cells (DC) following cryoablation of tumor is one of the personalized cancer immunotherapies which is able to induce immune responses to multiple endogenous tumor antigens, including shared and unique antigens. Here we describe protocols of cryoablation of tumors, generation of cultured DC, pretreatment of DC with a Toll-like receptor (TLR)-stimulating purified component of Bacillus Calmette-Guerin cell wall fraction (BCG-CWS) and highly immunogenic keyhole limpet hemocyanin (KLH) antigen, and combined use of tumor cryoablation and intratumoral administration of BCG-CWS-pretreated DC in both a murine model and cancer patients.

Identification of HLA-A2 or HLA-A24-restricted CTL epitopes for potential HSP105-targeted immunotherapy in colorectal cancer

We previously reported that heat shock protein 105 (HSP105) is overexpressed in a variety of human cancers, including colorectal, pancreatic and esophageal cancer and has proven to be a novel biomarker for the immunohistochemical detection of these cancers. In the present study, we used HLA-transgenic mice (Tgm) and the peripheral blood mononuclear cells (PBMCs) of colorectal cancer patients to identify HLA-A2 and HLA-A24-restricted HSP105 epitopes, as a means of expanding the application of HSP105-based immunotherapy to HLA-A2- or HLA-A24-positive cancer patients. In addition, we investigated by ex vivo IFN-γ ELISPOT assay whether the HSP105-derived peptide of cytotoxic T cells (CTLs) exists in PBMCs of pre-surgical colorectal cancer patients. We found that four peptides, HSP105 A2-7 (RLMNDMTAV), HSP105 A2-12 (KLMSSNSTDL), HSP105 A24-1 (NYGIYKQDL) and HSP105 A24-7 (EYVYEFRDKL), are potential HLA-A2 or HLA-A24-restricted CTL HSP105-derived epitopes. HSP105-specific IFN-γ-secreting T cells were detected in 14 of 21 pre-surgical patients with colorectal cancer in response to stimulation with these four peptides. Our study raises the possibility that these HSP105 peptides are applicable to cancer immunotherapy in patients with HSP105-expressing cancer, particularly colorectal cancer.

Anti-CCR4 mAb selectively depletes effector-type FoxP3+CD4+ regulatory T cells, evoking antitumor immune responses in humans

CD4(+) Treg cells expressing the transcription factor FOXP3 (forkhead box P3) are abundant in tumor tissues and appear to hinder the induction of effective antitumor immunity. A substantial number of T cells, including Treg cells, in tumor tissues and peripheral blood express C-C chemokine receptor 4 (CCR4). Here we show that CCR4 was specifically expressed by a subset of terminally differentiated and most suppressive CD45RA(-)FOXP3(hi)CD4(+) Treg cells [designated effector Treg (eTreg) cells], but not by CD45RA(+)FOXP3(lo)CD4(+) naive Treg cells, in peripheral blood of healthy individuals and cancer patients. In melanoma tissues, CCR4(+) eTreg cells were predominant among tumor-infiltrating FOXP3(+) T cells and much higher in frequency compared with those in peripheral blood. With peripheral blood lymphocytes from healthy individuals and melanoma patients, ex vivo depletion of CCR4(+) T cells and subsequent in vitro stimulation of the depleted cell population with the cancer/testis antigen NY-ESO-1 efficiently induced NY-ESO-1-specific CD4(+) T cells. Nondepletion failed in the induction. The magnitude of the responses was comparable with total removal of FOXP3(+) Treg cells by CD25(+) T-cell depletion. CCR4(+) T-cell depletion also augmented in vitro induction of NY-ESO-1-specific CD8(+) T cells in melanoma patients. Furthermore, in vivo administration of anti-CCR4 mAb markedly reduced the eTreg-cell fraction and augmented NY-ESO-1-specific CD8(+) T-cell responses in an adult T-cell leukemia-lymphoma patient whose leukemic cells expressed NY-ESO-1. Collectively, these findings indicate that anti-CCR4 mAb treatment is instrumental for evoking and augmenting antitumor immunity in cancer patients by selectively depleting eTreg cells.

Phenotypical analysis, relation to malignancy and prognostic relevance of ICOS+T regulatory and dendritic cells in patients with gliomas

We determined circulating T helper, T regulatory and ICOS+T regulatory as well as DC cell counts in 29 patients with cerebral gliomas. Samples from patients with gliomas vs. healthy controls and from patients with glioblastomas vs. patients with glioma WHO grades I-III contained significantly (p<0.05) decreased numbers of total as well as mature, i.e. myeloid and plasmacytoid DCs. Patients with glioblastomas demonstrated significantly lower values of CD4+ as well as an increased fraction of ICOS+T regulatory/CD4+ cells. Higher CD4+ cell counts (≥225 cells/μl, median) were associated with improved survival in glioblastomas.

Glioma stem cells and immunotherapy for the treatment of malignant gliomas

Stem cell research has led to the discovery of glioma stem cells (GSCs), and because these cells are resistant to chemotherapy and radiotherapy, analysis of their properties has been rapidly pursued for targeted treatment of malignant glioma. Recent studies have also revealed complex crosstalk between GSCs and their specialized environment (niche). Therefore, targeting not only GSCs but also their niche may be a principle for novel therapies of malignant glioma. One possible novel strategy for targeting GSCs and their niches is immunotherapy with different antitumor mechanism(s) from those of conventional therapy. Recent clinical studies of immunotherapy using peptide vaccines and antibodies have shown promising results. This review describes the recent findings related to GSCs and their niches, as well as immunotherapies for glioma, followed by discussion of immunotherapies that target GSCs for the treatment of malignant glioma.

Overcoming regulatory T-cell suppression by a lyophilized preparation of Streptococcus pyogenes

Cancer vaccines have yet to yield clinical benefit, despite the measurable induction of humoral and cellular immune responses. As immunosuppression by CD4(+) CD25(+) regulatory T (Treg) cells has been linked to the failure of cancer immunotherapy, blocking suppression is therefore critical for successful clinical strategies. Here, we addressed whether a lyophilized preparation of Streptococcus pyogenes (OK-432), which stimulates Toll-like receptors, could overcome Treg-cell suppression of CD4(+) T-cell responses in vitro and in vivo. OK-432 significantly enhanced in vitro proliferation of CD4(+) effector T cells by blocking Treg-cell suppression and this blocking effect depended on IL-12 derived from antigen-presenting cells. Direct administration of OK-432 into tumor-associated exudate fluids resulted in a reduction of the frequency and suppressive function of CD4(+) CD25(+) Foxp3(+) Treg cells. Furthermore, when OK-432 was used as an adjuvant of vaccination with HER2 and NY-ESO-1 for esophageal cancer patients, NY-ESO-1-specific CD4(+) T-cell precursors were activated, and NY-ESO-1-specific CD4(+) T cells were detected within the effector/memory T-cell population. CD4(+) T-cell clones from these patients had high-affinity TCRs and recognized naturally processed NY-ESO-1 protein presented by dendritic cells. OK-432 therefore inhibits Treg-cell function and contributes to the activation of high-avidity tumor antigen-specific naive T-cell precursors.

Melanoma as a model tumour for immuno-oncology

Melanoma is one of the most aggressive forms of skin cancer. Furthermore, incidence rates are increasing. Until recently, no agent had been shown to improve survival over supportive care and treatment guidelines recommended that patients with metastatic disease were entered into clinical trials. With so few treatment options available, there was a clear need for new, more effective treatments in this setting. Melanoma serves as a 'model' tumour for understanding immunity to cancer. Melanoma tumour-associated antigens were among the first cancer antigens to be identified and classified, with further studies showing that many of these are also expressed by other tumour types. In addition, melanoma regression has been associated with vitiligo, visibly confirming an active role of the immune system in this type of cancer, and spontaneous regression of primary melanomas has also been observed in some cases. These observations, relating to the activity of the immune system in melanoma, provided strong evidence that this tumour would be amenable to immunotherapy, with immunotherapies such as cytokines, adoptive cell transfer and T-cell modulators shown to be an effective therapeutic approach. Against this background, melanoma has long been at the cutting edge of immuno-oncology research and will likely continue to be used as a model tumour to increase our understanding of immuno-oncology and to inform development in other types of cancer.

Thymosin α1 and cancer: action on immune effector and tumor target cells

Since it was first identified, thymosin alpha 1 (Tα1) has been characterized to have pleiotropic effects on several pathological conditions, in particular as a modulator of immune response and inflammation. Several properties exerted by Tα1 may be attributable to a direct action on lymphoid cells. Tα1 has been shown to exert an immune modulatory activity on both T cell and natural killer cell maturation and to have an effect on functions of mature lymphocytes, including stimulating cytokine production and cytotoxic T lymphocyte-mediated cytotoxic responses. In previous studies we have shown that Tα1 increases the expression of major histocompatibility complex class I surface molecules in murine and human tumor cell lines and in primary cultures of human macrophages. In the present paper, we describe preliminary data indicating that Tα1 is also capable of increasing the expression of tumor antigens in both experimental and human tumor cell lines. This effect, which is exerted at the level of the target tumor cells, represents an additional factor increasing the antitumor activity of Tα1.

Adoptive transfer of siRNA Cblb-silenced CD8+ T lymphocytes augments tumor vaccine efficacy in a B16 melanoma model

The ubiquitin ligase Cbl-b is an established regulator of T cell immune response thresholds. We recently showed that adoptive cell transfer (ACT) of cblb(-/-) CD8(+) T cells enhances dendritic cell (DC) immunization-mediated anti-tumor effects in immune-competent recipients. However, translation of cblb targeting to clinically applicable concepts requires that inhibition of cblb activity be transient and reversible. Here we provide experimental evidence that inhibition of cblb using chemically synthesized siRNA has such potential. Silencing cblb expression by ex vivo siRNA transfection of polyclonal CD8(+) T cells prior to ACT increased T cell tumor infiltration, significantly delayed tumor outgrowth, and increased survival rates of tumor-bearing mice. As shown by ex vivo recall assays, cblb silencing resulted in significant augmentation of intratumoral T cell cytokine response. ACT of cblb-silenced polyclonal CD8(+) T cells combined with DC-based tumor vaccines predominantly mediated anti-tumor immune responses, whereas no signs of autoimmunity could be detected. Importantly, CBLB silencing in human CD8(+) T cells mirrored the effects observed for cblb-silenced and cblb-deficient murine T cells. Our data validate the concept of enhanced anti-tumor immunity by repetitive ACT of ex vivo cblb siRNA-silenced hyper-reactive CD8(+) T cells as add-on adjuvant therapy to augment the efficacy of existing cancer immunotherapy regimens in clinical practice.

Glioma antigen

Because several antigenic peptides of human tumors that are recognized by T-lymphocytes have been identified, immune responses against cancer can now be artificially manipulated. Furthermore, since T-lymphocytes have been found to play an important role in the rejection of tumors by the host and also to have antigen-specific proliferative potentials and memory mechanisms, T-lymphocytes are thought to play a central role in cancer vaccination. Although multidisciplinary therapies have been attempted for the treatment of gliomas, the results remain unsatisfactory. For the development of new therapies against gliomas, it is required to identify tumor antigens as targets for specific immunotherapy. In this chapter, recent progress in research on glioma antigens is described.

Intracellular Tumor-Associated Antigens Represent Effective Targets for Passive Immunotherapy

Monoclonal antibody (mAb) therapy against tumor antigens expressed on the tumor surface is associated with clinical benefit. However, many tumor antigens are intracellular molecules that generally would not be considered suitable targets for mAb therapy. In this study, we provide evidence challenging this view through an investigation of the efficacy of mAb directed against NY-ESO-1, a widely expressed immunogen in human tumors that is expressed intracellularly rather than on the surface of cells. On their own, NY-ESO-1 mAb could neither augment antigen-specific CD8+ T-cell induction nor cause tumor eradication. To facilitate mAb access to intracellular target molecules, we combined anti-NY-ESO-1 mAb with anticancer drugs to accentuate the release of intracellular NY-ESO-1 from dying tumor cells. Strikingly, combination therapy induced a strong antitumor effect that was accompanied by the development of NY-ESO-1–specific effector/memory CD8+ T cells that were not elicited by single treatments alone. The combinatorial effect was also associated with upregulation of maturation markers on dendritic cells, consistent with the organization of an effective antitumor T-cell response. Administration of Fc-depleted F(ab) mAb or combination treatment in Fcγ receptor–deficient host mice abolished the therapeutic effect. Together, our findings show that intracellular tumor antigens can be captured by mAbs and engaged in an efficient induction of CD8+ T-cell responses, greatly expanding the possible use of mAb for passive cancer immunotherapy. Cancer Res; 72(7); 1672–82. ©2012 AACR.

Immune microenvironments in solid tumors: new targets for therapy

Leukocytes and their soluble mediators play important regulatory roles in all aspects of solid tumor development. While immunotherapeutic strategies have conceptually held clinical promise, with the exception of a small percentage of patients, they have failed to demonstrate effective, consistent, and durable anti-cancer responses. Several subtypes of leukocytes that commonly infiltrate solid tumors harbor immunosuppressive activity and undoubtedly restrict the effectiveness of these strategies. Several of these same immune cells also foster tumor development by expression of potent protumor mediators. Given recent evidence revealing that immune-based mechanisms regulate the response to conventional cytotoxic therapy, it seems reasonable to speculate that tumor progression could be effectively diminished by combining cytotoxic strategies with therapies that blunt protumor immune-based effectors and/or neutralize those that instead impede development of desired anti-tumor immunity, thus providing synergistic effects between traditional cytotoxic and immune-modulatory approaches.

IL-21 can supplement suboptimal Lck-independent MAPK activation in a STAT-3-dependent manner in human CD8(+) T cells

Although both MHC class II/CD8α double-knockout and CD8β null mice show a defect in the development of MHC class I-restricted CD8(+) T cells in the thymus, they possess low numbers of high-avidity peripheral CTL with limited clonality and are able to contain acute and chronic infections. These in vivo data suggest that the CD8 coreceptor is not absolutely necessary for the generation of Ag-specific CTL. Lack of CD8 association causes partial TCR signaling because of the absence of CD8/Lck recruitment to the proximity of the MHC/TCR complex, resulting in suboptimal MAPK activation. Therefore, there should exist a signaling mechanism that can supplement partial TCR activation caused by the lack of CD8 association. In this human study, we have shown that CD8-independent stimulation of Ag-specific CTL previously primed in the presence of CD8 coligation, either in vivo or in vitro, induced severely impaired in vitro proliferation. When naive CD8(+) T cells were primed in the absence of CD8 binding and subsequently restimulated in the presence of CD8 coligation, the proliferation of Ag-specific CTL was also severely hampered. However, when CD8-independent T cell priming and restimulation were supplemented with IL-21, Ag-specific CD8(+) CTL expanded in two of six individuals tested. We found that IL-21 rescued partial MAPK activation in a STAT3- but not STAT1-dependent manner. These results suggest that CD8 coligation is critical for the expansion of postthymic peripheral Ag-specific CTL in humans. However, STAT3-mediated IL-21 signaling can supplement partial TCR signaling caused by the lack of CD8 association.

Cancer immunotherapy comes of age

Cancer immunotherapy comprises a variety of treatment approaches, incorporating the tremendous specificity of the adaptive immune system (T cells and antibodies) as well as the diverse and potent cytotoxic weaponry of both adaptive and innate immunity. Immunotherapy strategies include antitumor monoclonal antibodies, cancer vaccines, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate immune cells or block immune inhibitory pathways (so-called immune checkpoints). Although clear clinical efficacy has been demonstrated with antitumor antibodies since the late 1990s, other immunotherapies had not been shown to be effective until recently, when a spate of successes established the broad potential of this therapeutic modality. These successes are based on fundamental scientific advances demonstrating the toleragenic nature of cancer and the pivotal role of the tumor immune microenvironment in suppressing antitumor immunity. New therapies based on a sophisticated knowledge of immune-suppressive cells, soluble factors, and signaling pathways are designed to break tolerance and reactivate antitumor immunity to induce potent, long-lasting responses. Preclinical models indicate the importance of a complex integrated immune response in eliminating established tumors and validate the exploration of combinatorial treatment regimens, which are anticipated to be far more effective than monotherapies. Unlike conventional cancer therapies, most immunotherapies are active and dynamic, capable of inducing immune memory to propagate a successful rebalancing of the equilibrium between tumor and host.

Regulatory T cells in colorectal cancer: from biology to prognostic relevance

Regulatory T cells (Tregs) were initially described as "suppressive" lymphocytes in the 1980s. However, it took almost 20 years until the concept of Treg-mediated immune control in its present form was finally established. Tregs are obligatory for self-tolerance and defects within their population lead to severe autoimmune disorders. On the other hand Tregs may promote tolerance for tumor antigens and even hamper efforts to overcome it. Intratumoral and systemic accumulation of Tregs has been observed in various types of cancer and is often linked to worse disease course and outcome. Increase of circulating Tregs, as well as their presence in mesenteric lymph nodes and tumor tissue of patients with colorectal cancer de facto suggests a strong involvement of Tregs in the antitumor control. This review will focus on the Treg biology in view of colorectal cancer, means of Treg accumulation and the controversies regarding their prognostic significance. In addition, a concise overview will be given on how Tregs and their function can be targeted in cancer patients in order to bolster an inherent immune response and/or increase the efficacy of immunotherapeutic approaches.

Serum anti-BPAG1 auto-antibody is a novel marker for human melanoma

Malignant melanoma is one of the most aggressive types of tumor. Because malignant melanoma is difficult to treat once it has metastasized, early detection and treatment are essential. The search for reliable biomarkers of early-stage melanoma, therefore, has received much attention. By using a novel method of screening tumor antigens and their auto-antibodies, we identified bullous pemphigoid antigen 1 (BPAG1) as a melanoma antigen recognized by its auto-antibody. BPAG1 is an auto-antigen in the skin disease bullous pemphigoid (BP) and anti-BPAG1 auto-antibodies are detectable in sera from BP patients and are used for BP diagnosis. However, BPAG1 has been viewed as predominantly a keratinocyte-associated protein and a relationship between BPAG1 expression and melanoma has not been previously reported. In the present study, we show that bpag1 is expressed in the mouse F10 melanoma cell line in vitro and F10 melanoma tumors in vivo and that BPAG1 is expressed in human melanoma cell lines (A375 and G361) and normal human melanocytes. Moreover, the levels of anti-BPAG1 auto-antibodies in the sera of melanoma patients were significantly higher than in the sera of healthy volunteers (p<0.01). Furthermore, anti-BPAG1 auto-antibodies were detected in melanoma patients at both early and advanced stages of disease. Here, we report anti-BPAG1 auto-antibodies as a promising marker for the diagnosis of melanoma, and we discuss the significance of the detection of such auto-antibodies in cancer biology and patients.

Serologic markers of effective tumor immunity against chronic lymphocytic leukemia include nonmutated B-cell antigens

Patients with chronic lymphocytic leukemia (CLL) who relapse after allogeneic transplant may achieve durable remission following donor lymphocyte infusion (DLI), showing the potency of donor-derived immunity in eradicating tumors. We sought to elucidate the antigenic basis of the effective graft-versus-leukemia (GvL) responses associated with DLI for the treatment of CLL by analyzing the specificity of plasma antibody responses developing in two DLI-treated patients who achieved long-term remission without graft-versus-host disease. By probing high-density protein microarrays with patient plasma, we discovered 35 predominantly intracellular antigens that elicited high-titer antibody reactivity greater in post-DLI than in pre-DLI plasma. Three antigens-C6orf130, MDS032, and ZFYVE19-were identified by both patients. Along with additional candidate antigens DAPK3, SERBP1, and OGFOD1, these proteins showed higher transcript and protein expression in B cells and CLL cells compared with normal peripheral blood mononuclear cells. DAPK3 and the shared antigens do not represent minor histocompatibility antigens, as their sequences are identical in both donor and tumor. Although ZFYVE19, DAPK3, and OGFOD1 elicited minimal antibody reactivity in 12 normal subjects and 12 chemotherapy-treated CLL patients, 5 of 12 CLL patients with clinical GvL responses were serologically reactive to these antigens. Moreover, antibody reactivity against these antigens was temporally correlated with clinical disease regression. These B-cell antigens represent promising biomarkers of effective anti-CLL immunity.

Profiling humoral immune responses to P. falciparum infection with protein microarrays

A complete description of the serological response following exposure of humans to complex pathogens is lacking and approaches suitable for accomplishing this are limited. Here we report, using malaria as a model, a method which elucidates the profile of antibodies that develop after natural or experimental infection or after vaccination with attenuated organisms, and which identifies immunoreactive antigens of interest for vaccine development or other applications. Expression vectors encoding 250 Plasmodium falciparum (Pf) proteins were generated by PCR/recombination cloning; the proteins were individually expressed with >90% efficiency in Escherichia coli cell-free in vitro transcription and translation reactions, and printed directly without purification onto microarray slides. The protein microarrays were probed with human sera from one of four groups which differed in immune status: sterile immunity or no immunity against experimental challenge following vaccination with radiation-attenuated Pf sporozoites, partial immunity acquired by natural exposure, and no previous exposure to Pf. Overall, 72 highly reactive Pf antigens were identified. Proteomic features associated with immunoreactivity were identified. Importantly, antibody profiles were distinct for each donor group. Information obtained from such analyses will facilitate identifying antigens for vaccine development, dissecting the molecular basis of immunity, monitoring the outcome of whole-organism vaccine trials, and identifying immune correlates of protection.

Allovectin-7 therapy in metastatic melanoma

BACKGROUND

Patients with metastatic melanoma are immunosuppressed by the growing tumor. Allovectin-7 therapy is a form of active immunotherapy that aims at immunization of the host with substances designed to elicit an immune reaction that will eliminate or slow down the growth and spread of the cancer.

OBJECTIVE

to describe the rationale for immunotherapy with Allovectin-7 and assess its safety profile and efficacy based on the results of completed melanoma clinical trials.

METHODS

we reviewed both the published medical literature and the results of trials pending publication.

RESULTS/CONCLUSION

Allovectin-7 is a safe and active immunotherapeutic agent. It induces local and systemic durable responses in patients with metastatic melanoma.

T regulatory type 1 cells in squamous cell carcinoma of the head and neck: mechanisms of suppression and expansion in advanced disease

PURPOSE

Regulatory T cells play a major role in tumor escape from immunosurveillance. T regulatory cells type 1 (Tr1), a subset of regulatory T cells present in the tumor and peripheral circulation of patients with head and neck squamous cell carcinoma (HNSCC), mediate immune suppression and might contribute to tumor progression.

EXPERIMENTAL DESIGN

CD4+CD25-T cells were isolated from peripheral blood mononuclear cells (PBMC) or tumor-infiltrating lymphocytes (TIL) of 26 HNSCC patients and 10 normal controls. The Tr1 cell phenotype was determined before and after culture in the presence of interleukin (IL)-2, IL-10, and IL-15, each at 10 to 20 IU/mL. Suppression was measured in carboxyfluorescein diacetate succinimidyl ester-based proliferation assays with or without neutralizing anti-IL-10 or anti-transforming growth factor-beta1 (TGF-beta1) monoclonal antibodies in Transwell systems. ELISA was used to define the Tr1 cytokine profile.

RESULTS

Tr1 cells originate from CD4(+)CD25(-) precursors present in TIL and PBMC of HNSCC patients. Cytokine-driven ex vivo expansion of Tr1 precursors yielded CD4+CD25-Foxp3lowCD132+IL-10+TGF-beta1+ populations that mediated higher suppression than Tr1 cells of normal controls (P < 0.0001). Tr1 cells suppressed proliferation of autologous responders via IL-10 and TGF-beta1 secretion. Expression of these cytokines was higher in TIL-derived than PBMC-derived Tr1 cells (P < 0.0001). The Tr1 cell frequency and suppressor function were significantly higher in patients presenting with advanced than early disease stages and in patients "cured" by oncologic therapies than in those with active disease.

CONCLUSIONS

In HNSCC, Tr1 cell generation is promoted at the tumor site. Tr1 cells use TGF-beta and IL-10 to mediate suppression. They expand during disease progression and also following cancer therapy in patients with no evident disease.

Lung epithelial NF-kappaB and Stat1 signaling in response to CD8+ T cell antigen recognition

CD8+ T cell recognition of viral antigens presented by lung epithelial cells is important in the clearance of respiratory viral infection but may cause considerable injury to the lung. We have shown that a critical event of this type of injury is the activation of target epithelial cells and expression of chemokines by these cells. In this study, epithelial gene expression and transcription factor activation triggered by specific CD8+ T cell antigen recognition was examined in vitro and in vivo. T cell recognition triggers expression profiles of tumor necrosis factor-alpha (TNF-alpha)-dependent and interferon-gamma (IFN-gamma)-dependent genes in epithelial target cells. Consistent with these profiles, transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) were activated in lung epithelial cells of wild-type (WT) mice but not TNF receptor 1 (TNFR1)-deficient mice after CD8+ T cell recognition in vivo. In contrast, Stat1 activation and Stat1-dependent genes, such as IFN regulatory factor-1 (IRF-1) and guanylate-binding protein-2 (GBP-2), were induced to a similar extent in epithelial cells of both WT and TNFR1-deficient mice, indicating that this pathway is insufficient to induce pulmonary immunopathology in the absence of NF-kappaB-dependent transcriptional activation. Antibody neutralization of TNF-alpha abrogated epithelial monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) production in vitro as well as pulmonary immunopathology in vivo, confirming the primary importance of this cytokine in CD8+ T cell-mediated immunopathology.

Enhancement of immunologic tumor regression by intratumoral administration of dendritic cells in combination with cryoablative tumor pretreatment and Bacillus Calmette-Guerin cell wall skeleton stimulation

PURPOSE

We developed an effective immunotherapy, which could induce antitumor immune responses against shared and unique tumor antigens expressed in autologous tumors.

EXPERIMENTAL DESIGN

Intratumoral administration of dendritic cells is one of the individualized immunotherapies; however, the antitumor activity is relatively weak. In this study, we attempted to enhance the antitumor efficacy of the i.t. dendritic cell administration by combining dendritic cells stimulated with Bacillus Calmette-Guerin cell wall skeleton (BCG-CWS) additionally with cryoablative pretreatment of tumors and analyzed the therapeutic mechanisms.

RESULTS

These two modifications (cryoablation of tumors and BCG-CWS stimulation of dendritic cells) significantly increases the antitumor effect on both the treated tumor and the untreated tumor, which was distant at the opposite side, in a bilateral s.c. murine CT26 colon cancer model. Further analysis of the augmented antitumor effects revealed that the cryoablative pretreatment enhances the uptake of tumor antigens by the introduced dendritic cells, resulting in the induction of tumor-specific CD8(+) T cells responsible for the in vivo tumor regression of both treated and remote untreated tumors. This novel combination i.t. dendritic cell immunotherapy was effective against well-established large tumors. The antitumor efficacy was further enhanced by depletion of CD4(+)CD25(+)FoxP3(+) regulatory T cells.

CONCLUSIONS

This novel dendritic cell immunotherapy with i.t. administration of BCG-CWS-treated dendritic cells following tumor cryoablation could be used for the therapy of cancer patients with multiple metastases.

Identification of HLA-A2- or HLA-A24-restricted CTL epitopes possibly useful for glypican-3-specific immunotherapy of hepatocellular carcinoma

PURPOSE AND EXPERIMENTAL DESIGN

We previously reported that glypican-3 (GPC3) was overexpressed, specifically in hepatocellular carcinoma (HCC) and melanoma in humans, and it was useful as a novel tumor marker. We also reported that the preimmunization of BALB/c mice with dendritic cells pulsed with the H-2K(d)-restricted mouse GPC3(298-306) (EYILSLEEL) peptide prevented the growth of tumor-expressing mouse GPC3. Because of similarities in the peptide binding motifs between H-2K(d) and HLA-A24 (A*2402), the GPC3(298-306) peptide therefore seemed to be useful for the immunotherapy of HLA-A24+ patients with HCC and melanoma. In this report, we investigated whether the GPC3(298-306) peptide could induce GPC3-reactive CTLs from the peripheral blood mononuclear cells (PBMC) of HLA-A24 (A*2402)+ HCC patients. In addition, we used HLA-A2.1 (HHD) transgenic mice to identify the HLA-A2 (A*0201)-restricted GPC3 epitopes to expand the applications of GPC3-based immunotherapy to the HLA-A2+ HCC patients.

RESULTS

We found that the GPC3(144-152) (FVGEFFTDV) peptide could induce peptide-reactive CTLs in HLA-A2.1 (HHD) transgenic mice without inducing autoimmunity. In five out of eight HLA-A2+ GPC3+ HCC patients, the GPC3(144-152) peptide-reactive CTLs were generated from PBMCs by in vitro stimulation with the peptide and the GPC3(298-306) peptide-reactive CTLs were also generated from PBMCs in four of six HLA-A24+ GPC3+ HCC patients. The inoculation of these CTLs reduced the human HCC tumor mass implanted into nonobese diabetic/severe combined immunodeficiency mice.

CONCLUSION

Our study raises the possibility that these GPC3 peptides may therefore be applicable to cancer immunotherapy for a large number of HCC patients.

Tumor antigen expression in melanoma varies according to antigen and stage

PURPOSE

Melanoma cells express antigens that can induce T-cell and antibody responses. Obtaining a detailed understanding of antigen expression in primary and metastatic melanoma is essential if these molecules are to be useful targets for immunotherapy of melanoma.

EXPERIMENTAL DESIGN

Malignant melanomas (n = 586) from 426 patients were typed for antigen expression. Multiple samples were available from 86 individuals, enabling analysis of antigen expression patterns over time. Paraffin-embedded samples were tested by immunohistochemistry for the presence of the differentiation antigens: gp100, Melan-A, tyrosinase, and the "cancer/testis" antigens MAGE-A1, MAGE-A4, and NY-ESO-1.

RESULTS

Samples were primary tumors (n = 251), lymph node metastases (n = 174), s.c. metastases (n = 71), and distant metastases (n = 90). The differentiation antigens were strongly expressed in 93% to 95% of tumors regardless of stage. In contrast, the frequency of cancer/testis antigen expression in primary tumors for MAGE-A1, MAGE-A4, and NY-ESO-1 was lower (20%, 9%, and 45%, respectively). MAGE-A1 and MAGE-A4 were acquired with advancing disease (to 51% and 44% in distant metastases, respectively) but not NY-ESO-1, which remained positive in 45%. MAGE-A1 expression was twice as prevalent in ulcerated primaries as in nonulcerated primaries (30% versus 15%; P = 0.006) and in thicker as opposed to thin melanomas (26% versus 10%; P = 0.1).

CONCLUSIONS

This large series describes patterns of antigen expression in melanoma and their evolution over time. This will help inform decisions about selection of patients and target antigens for melanoma immunotherapy clinical trials.

Possible involvement of allogeneic antigens recognised by donor-derived CD4 cytotoxic T cells in selective GVL effects after stem cell transplantation of patients with haematological malignancy

Cytotoxic T lymphocyte (CTL) lines specific for allogeneic antigens were generated by in vitro stimulation of donor-derived peripheral blood mononuclear cells obtained from patients who received human leucocyte antigen (HLA)-matched allogeneic haematopoietic stem cell transplantation (HSCT). One of the allogeneic antigen-specific CD4+ CTL lines, CTL-A, generated from a patient with T cell acute lymphoblastic leukaemia, recognised HLA-DPB1*0501-positive Epstein-Barr virus-immortalised human B cell line (EBV-B cells), phytohaemagglutinin blasts and leukaemia cells, but not interferon-gamma (IFN-gamma) treated HLA-DPB1*0501-positive fibroblasts, indicating that this CD4+ T-cell line recognised a minor histocompatibility antigen (mHa) that is preferentially expressed in haematopoietic cells in an HLA-DPB1*0501-restricted manner. The other CD4+ CTL line, CTL-B, generated from a patient with chronic myeloid leukaemia, recognised mismatched HLA-DQB1*0303 on EBV-B cells and phytohaemagglutinin (PHA) blasts. Interestingly, this CTL line did not recognise IFN-gamma-treated recipient's skin fibroblasts, as HLA-DQ was merely upregulated even after IFN-gamma stimulation in non-haematopoietic cells including fibroblasts, endothelial cells and hepatocytes. These results suggest that these CD4 positive CTLs, specific for mismatch HLA-DQ and mHa that are preferentially expressed on haematopoietic cells, may play an important role in induction of selective graft-versus-leukaemia effect without development of graft-versus-host disease after allogeneic HSCT.

Qualitative difference between the cytotoxic T lymphocyte responses to melanocyte antigens in melanoma and vitiligo

Vitiligo is a skin disorder characterized by depigmented macules secondary to melanocyte loss. An unusual facet is its relation to melanoma: cytotoxic T lymphocytes directed to melanocyte antigens are found in both conditions and imply a breakdown of tolerance, yet the resulting immune reaction is the opposite. The mechanisms at the basis of these opposite effects are not known. Here, we performed a direct comparison of whole melanocyte-specific T cell populations in the two diseases. We demonstrate that neither precursor frequencies of Melan-A/MART-1-specific T lymphocytes nor their status of activation differ significantly. However, by using a tetramer-based T cell receptor down-regulation assay, we documented a higher affinity of vitiligo T cells. We calculated that the peptide concentration required for 50% of maximal receptor down-regulation differed by 6.5-fold between the two diseases. Moreover, only vitiligo T cells were capable of efficient receptor down-regulation and IFN-gamma production in response to HLA-matched melanoma cells, suggesting that this difference in receptor affinity is physiologically relevant. The differences in receptor affinity and tumor reactivity were confirmed by analyzing Melan-A/MART-1-specific clones established from the two diseases. Our results suggest that the quality, and not the quantity, of the melanocyte-specific cytotoxic responses differs between the two pathologies.

Melanocyte-specific, cytotoxic T cell responses in vitiligo: the effective variant of melanoma immunity?

Vitiligo is a relatively common progressive depigmentary condition that is believed to be due to the autoimmune-mediated loss of epidermal melanocytes. An interesting aspect of vitiligo is its relation to melanoma: cytotoxic T lymphocytes directed to self-antigens shared by normal melanocytes and melanoma cells are found in both conditions and might prove important in melanocyte destruction, yet the resulting immune reactions are completely different. From this standpoint, the selective destruction of pigment cells that occurs in cases of vitiligo is the therapeutic goal sought in melanoma research. In the present article, we will address these issues by reviewing current literature on the subject as well as by posing some speculations.

Quantitation and visualization of tumor-specific T cells in the secondary lymphoid organs during and after tumor elimination by PET

Increased understanding in the area of trafficking behavior of adoptively transferred tumor-specific T cells could help develop better therapeutic protocols. We utilized the DUC18/CMS5 tumor model system in conjunction with a microPET scanner to study the DUC18 T cell distribution pattern in spleens and lymph nodes in live mice. Anti-Thy1.2 antibodies conjugated to 1,4,7,10-tetraazacyclododecane-N,N',N'',N''-tetraacetic acid (DOTA) and radiolabeled with (64)Cu were administered to three groups of BALB-Thy1.1 mice on days 4, 7, or 14 post-DUC18 T cell transfer. We were able to detect the transferred cells in all the major lymph nodes, spleens, and in tumors. Our findings suggest that tumor-specific T cells do not all preferentially localize to the tumors but they also home to all the major lymphoid organs; additionally the number of DUC18 T cells remains relatively constant during and after tumor elimination within each lymphoid organ.

Immunological detection of altered signaling molecules involved in melanoma development

To understand immune responses to human cancer and develop more effective immunotherapy, human tumor antigens has been isolated using various immunological methods with tumor reactive T cells or antibodies obtained from patients with melanoma. During the process of tumor antigen isolation, various molecules with genetic alterations or over-expression in tumor cells, which may be involved in proliferation, differentiation, or survival of various cancer cells, were identified. In melanoma, abnormal molecules with mutations including beta -catenin, CDK4, and BRAF, and molecules with increased expression including Survivin, were immunologically detected. Therefore, immunological isolation of human tumor antigens contributes to the identification of important molecules including altered signaling molecules involved in melanoma formation.

Immunotherapy and chemotherapy--a practical partnership

This article discusses how recent data have altered the way we understand how dying tumour cells, particularly those killed by chemotherapy, engage with antitumour immune responses. These data have significant implications for the development of new protocols combining chemotherapy with immunotherapy, indicating an exciting potential for therapeutic synergy with general applicability to many cancer types.

Novel melanoma antigen, FCRL/FREB, identified by cDNA profile comparison using DNA chip are immunogenic in multiple melanoma patients

We applied a strategy that utilized a combination of systematic gene expression analysis with various tissues and immunological detection with sera from melanoma patients to identify melanoma antigens expressed preferentially in melanoma and melanocytes. We selected 101 genes by comparing cDNA profiles obtained by GeneChip analysis of a highly pigmented melanoma cell line, SKmel23, primary cultured melanocytes, HUVECs cultured endothelial cells, keratinocytes, liver and stomach. After the additional selection with criterion of high registered frequency of each cDNA in melanocyte-related cDNA libraries in the NCBI database, 15 genes including 12 known melanocyte specific genes were identified. One of the remaining 3 genes, FCRL/FREB, encoding a member of the Fc receptor family that was previously reported to express in germinal center B cells, was found to express preferentially in melanocytes and melanoma tissues by RT-PCR and Northern blot analysis. The FCRL/FREB protein was detected in the cytoplasm of melanoma cells by staining with the murine polyclonal antibody and by transfection with GFP-fused FCRL/FREB cDNA. The bacterial recombinant protein was recognized by serum IgG antibody obtained from some patients with melanoma. These results suggest that FCRL/FREB may function in melanocytes and melanoma and may be useful for development of diagnostic methods for various pigment disorders and immunotherapy of melanoma.

A listing of human tumor antigens recognized by T cells: March 2004 update

The technological advances occurred in the last few years have led to a great increase in the number of tumor associated antigens (TAA) that are currently available for clinical applications. In this review we provide a comprehensive list of human tumor antigens as reported in the literature updated at February 2004. The list includes all T cell-defined epitopes, while excluding analogs or artificially modified epitopes, as well as virus-encoded and antibodies-recognized antigens. TAAs are listed in alphabetical order along with the epitope sequence and the HLA allele which restricts recognition by T cells. Data on the tissue distribution of each antigen are also provided together with an extensive bibliography that allows a rapid search for any additional information may be needed on each single antigen or epitope. Overall, the updated list is a database tool for clinicians, scientists and students who have an interest in the field of tumor immunology and immunotherapy.

Development of HVJ Envelope Vector and Its Application to Gene Therapy

To create a highly efficient vector system that is minimally invasive, we initially developed liposomes that contained fusion proteins from the hemagglutinating virus of Japan (HVJ; Sendai virus). These HVJ-liposomes delivered genes and drugs to cultured cells and tissues. To simplify the vector system and develop more efficient vectors, the next approach was to convert viruses to non-viral vectors. Based on this concept, we recently developed the HVJ envelope vector. HVJ with robust fusion activity was inactivated, and exogenous DNA was incorporated into the viral envelope by detergent treatment and centrifugation. The resulting HVJ envelope vector introduced plasmid DNA efficiently and rapidly into both cultured cells in vitro and organs in vivo. Furthermore, proteins, synthetic oligonucleotides, and drugs have also been effectively introduced into cells using the HVJ envelope vector. The HVJ envelope vector is a promising tool for both ex vivo and in vivo gene therapy experiments. Hearing impairment in rats was prevented and treated by hepatocyte growth factor gene transfer to cerebrospinal fluid using HVJ envelope vector. For cancer treatment, tumor-associated antigen genes were delivered efficiently to mouse dendritic cells to evoke an anti-cancer immune response. HVJ envelope vector fused dendritic cells and tumor cells and simultaneously delivered cytokine genes, such as IL-12, to the hybrid cells. This strategy successfully prevented and treated cancers in mice by stimulating the presentation of tumor antigens and the maturation of T cells. For human gene therapy, a pilot plant to commercially produce clinical grade HVJ envelope vector has been established.