Humoral immune response against melanoma antigens induced by vaccination with cytokine gene-modified autologous tumor cells

The investigation of relevancy between PIAS1 and PIAS2 gene expression and disease severity of multiple sclerosis

Introduction: PIAS1 and PIAS2 (protein inhibitor of activated STAT 1,2) play key roles in the pathogenesis of autoimmune and inflammatory diseases. This study aims to evaluate the gene expression of these factors in multiple sclerosis (MS) patients compared to healthy individuals and correlate them with the severity of MS. Materials and methods: Sixty participants, including 30 patients with MS and 30 healthy controls were studied. The expression of PIAS1 and PIAS2 genes in peripheral blood samples of all participants was measured by real-time PCR. The severity of MS was evaluated using the Expanded Disability Status Scale (EDSS). Finally, we evaluated the correlation between the expression of PIAS1 and PIAS2 genes with disease severity. Results: The expression of PIAS1 gene was increased in patients with MS compared to healthy subjects (P value<.001). Also, there was a significant correlation between the expression of PIAS1 and PIAS2 genes with disease severity according to EDSS. Conclusion: Our study suggests the expression of PIAS1 and PIAS2 genes as a prognostic and diagnostic marker in MS disease.

The revival of cancer vaccines - The eminent need to activate humoral immunity

In light of the increasing number of approved monoclonal antibodies for the treatment of cancer, it seems peculiar that the development of antibody inducing vaccines gets so little attention. In our view there is a tremendous opportunity in the development of cancer vaccines inducing humoral immune responses, involving a couple of major advantages. Firstly, the effectivity of a polyclonal antibody response is expected to exceed the one of monoclonal antibodies. This is supported by preclinical data that show pronounced anti-tumor responses and early clinical trials in which benefit is observed in patients with advanced cancer. Secondly, vaccination strategies are expected to reduce hospital visits, resulting in enhanced quality of life. And last but not least, vaccination strategies are extremely cost effective, alleviating the socioeconomic problems of prohibitively high drug costs. To reach further clinical success, efforts should focus on target identification, optimization of vaccination strategies and adjuvant development.

Autologous versus allogeneic cell-based vaccines?

Devitalized tumor cells either autologous or allogeneic have been used as anti-cancer vaccines with the purpose of facilitating the induction of an immune response able to destroy growing tumor cells since the identification of tumor antigens was deemed not to be necessary, particularly in the autologous system. Such vaccines were tested first in animal models and then in the clinics as unmodified tumor cells or after insertion of genes coding for factors known to increase the immune response against tumors. These vaccines were usually given by subcutaneous injections along with different immunological adjuvants. Such immunization approaches were found to be effective in mice when carried out in a tumor preventive setting but significantly less in the therapeutic context, that is, in the presence of an established tumor. By analyzing several clinical trials of vaccination using either autologous or allogeneic unmodified and gene-modified tumor cells published in the last 10 to 15 years, we conclude for a lack of sufficient evidence for efficacy of this strategy in inducing both a strong immune response and a therapeutic response. A potential variant of this strategy is the direct intratumoral injection of immunostimulatory genes delivered by vectors in vivo. But even this approach failed to provide a statistically significant clinical benefit for the cancer patients.We also point out the inherent drawbacks of the tumor cell-based vaccine strategy that include (a) a limited frequency by which human tumor lines can be obtained from clinical samples, (b) the low number of available cells for vaccination, (c) the release of immune-suppressive factors by tumor cells, and (d) the cost and time necessary for standardization and collecting/expanding a number of cells according to the approved regulatory requirements. Thus, taking into consideration the new developments in cancer vaccines, we believe that tumor cell-based vaccines should be dismissed as anti-cancer vaccines unless a clear benefit could be demonstrated by the few ongoing trials of combination with new immunomodulating reagents (eg, anti-CTLA4, PD-1, chemotherapy).

Identification of Autoantibodies for α and γ-Enolase in Serum from a Patient with Melanoma

Melanoma is one of lethal malignant skin tumors and the sole effective cure for the disease can be achieved by surgical resection of primary tumor and early diagnosis for melanoma is crucial for patients’ prognosis. Detection of novel tumor-related antibodies would aid in the diagnosis of early-stage cancer, in the detection of recurrence and in the development of a more effective immunotherapy. In the middle of the exploration of a candidate of biomarker for melanoma by proteomics-base technique, we encountered the coexistence of autoantibodies for α-enolase and γ-enolase in serum derived from a patient with melanoma, who had received the repeated treatments with alkylating agents and interferon β. Although melanoma is known to be a highly antigenic tumor, it is still unclear why these autoantibodies appeared. To evaluate the usefulness in detecting the circulating α-enolase or γ-enolase autoantibodies in serum from melanoma patients for biomarkers for tumor progression, more studies are needed.

T cells reactive with HLA-A*0201 peptides from the histone demethylase JARID1B are found in the circulation of breast cancer patients

The nuclear protein PLU-1/JARID1B/KDM5 is widely expressed in breast cancers while showing highly restricted expression in normal adult tissues. To investigate whether JARID1B is a potential target antigen for immunotherapy of breast cancer, we have analyzed the responses of CD8(+) T cells to JARID1B HLA-A*0201 peptides in vitro and used peptide multimers to detect the presence of JARID1B reactive T cells in the circulation of breast cancer patients. Peptides were selected using two web-based algorithms: criteria for inclusion being a high score in both prediction algorithms, and nonhomology with retinoblastoma binding protein-2 (RBP2/JARID1A/KDM5A). A 65-peptide panel was selected and assayed for binding strength by competition assay to obtain the IC(50). The immunogenicity in vitro of these peptides was assessed by T cell stimulation experiments, using autologous dendritic cells as APCs in the first rounds followed by autologous lymphoblasts. Fourteen of the peptides assayed produced cultures having >2% of the CD8(+) cells being IFN-γ(+) after 3-6 rounds of stimulation. An HLA-A*0201 cell line could activate the specific T cells if pulsed with peptide, but endogenous peptide levels were insufficient for activation. Nevertheless, multimer staining of circulating T cells from breast cancer patients showed a significantly higher percentage of multimer positive CD8(+) T cells, as compared to healthy adults for two of three JARID1B epitopes tested. One of these, peptide 73 (QLYALPCVL), was analyzed for memory phenotype, and found to have a significantly higher proportion of central memory T cells than the control group, demonstrating a previous exposure to the peptide.

Metastatic melanomas express inhibitory low affinity fc gamma receptor and escape humoral immunity

Our research, inspired by the pioneering works of Isaac Witz in the 1980s, established that 40% of human metastatic melanomas express ectopically inhibitory Fc gamma receptors (FcγRIIB), while they are detected on less than 5% of primary cutaneous melanoma and not on melanocytes. We demonstrated that these tumoral FcγRIIB act as decoy receptors that bind the Fc portion of antimelanoma IgG, which may prevent Fc recognition by the effector cells of the immune system and allow the metastatic melanoma to escape the humoral/natural immune response. The FcγRIIB is able to inhibit the ADCC (antibody dependent cell cytotoxicity) in vitro. Interestingly, the percentage of melanoma expressing the FcγRIIB is high (70%) in organs like the liver, which is rich in patrolling NK (natural killer) cells that exercise their antitumoral activity by ADCC. We found that this tumoral FcγRIIB is fully functional and that its inhibitory potential can be triggered depending on the specificity of the anti-tumor antibody with which it interacts. Together these observations elucidate how metastatic melanomas interact with and potentially evade humoral immunity and provide direction for the improvement of anti-melanoma monoclonal antibody therapy.

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.

Overview of Tumor Cell–Based Vaccines

Whole-cell tumor vaccines have been investigated for more than 20 years for their efficacy in both preclinical models and in clinical trials in humans. There are clear advantages of whole-cell/polyepitope vaccination over those types of immunotherapy that target specific epitopes. Multiple and unknown antigens may be targeted to both the innate and adaptive immune system, and this may be further augmented by genetic modification of the vaccine cells to provide cytokines and costimulation. In this review, we give an overview of the field including the preclinical and clinical advances using unmodified and modified tumor-cell vaccines.

Proteome serological determination of tumor-associated antigens in melanoma

Proteome serology may complement expression library-based approaches as strategy utilizing the patients' immune responses for the identification pathogenesis factors and potential targets for therapy and markers for diagnosis. Melanoma is a relatively immunogenic tumor and antigens recognized by melanoma-specific T cells have been extensively studied. The specificities of antibody responses to this malignancy have been analyzed to some extent by molecular genetic but not proteomics approaches. We screened sera of 94 melanoma patients for anti-melanoma reactivity and detected seropositivity in two-thirds of the patients with 2–6 antigens per case detected by 1D and an average of 2.3 per case by 2D Western blot analysis. For identification, antigen spots in Western blots were aligned with proteins in 2-DE and analyzed by mass spectrometry. 18 antigens were identified, 17 of which for the first time for melanoma. One of these antigens, galectin-3, has been related to various oncogenic processes including metastasis formation and invasiveness. Similarly, enolase has been found deregulated in different cancers. With at least 2 of 18 identified proteins implicated in oncogenic processes, the work confirms the potential of proteome-based antigen discovery to identify pathologically relevant proteins.

Selective expression of inhibitory Fcgamma receptor by metastatic melanoma impairs tumor susceptibility to IgG-dependent cellular response

During melanoma progression, patients develop anti-tumor immunity including the production of anti-tumor antibodies. Although the strategies developed by malignant cells to escape anti-tumor cellular immunity have been extensively investigated, little is known about tumor resistance to humoral immunity. The main effect of IgG antibodies is to activate the immune response by binding to host Fc gamma receptors (FcgammaR) expressed by immune cells. We previously reported in a limited study that some human metastatic melanoma cells ectopically express the FcgammaRIIB1, an inhibitory isoform of FcgammaR. By analyzing a large panel of different types of human primary and metastatic solid tumors, we report herein that expression of FcgammaRIIB is restricted to melanoma and is acquired during tumor progression. We show that FcgammaRIIB expression prevents the lysis of human metastatic melanoma cells by NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) in vitro, independently of the intracytoplasmic region of FcgammaRIIB. Using experimental mouse models, we demonstrate that expression of FcgammaRIIB protects B16F0 melanoma tumors from the ADCC induced by monoclonal and polyclonal anti-tumor IgG in vivo. Thus, our results identify FcgammaRIIB as a marker of human metastatic melanoma that impairs the tumor susceptibility to FcgammaR-dependent innate effector responses.

Effects of IL-7 on memory CD8 T cell homeostasis are influenced by the timing of therapy in mice

IL-7 is integral to the generation and maintenance of CD8(+) T cell memory, and insufficient IL-7 is believed to limit survival and the persistence of memory CD8(+) T cells. Here, we show that during the mouse T cell response to lymphocytic choriomeningitis virus, IL-7 enhanced the number of memory CD8(+) T cells when its administration was restricted to the contraction phase of the response. Likewise, IL-7 administration during the contraction phase of the mouse T cell response to vaccinia virus or a DNA vaccine potentiated antigen-specific CD8(+) memory T cell proliferation and function. Qualitatively, CD8(+) T cells from IL-7-treated mice exhibited superior recall responses and improved viral control. IL-7 treatment during the memory phase stimulated a marked increase in the number of memory CD8(+) T cells, but the effects were transient. IL-7 therapy during contraction of the secondary CD8(+) T cell response also expanded the pool of memory CD8(+) T cells. Collectively, our studies show differential effects of IL-7 on memory CD8(+) T cell homeostasis and underscore the importance of the timing of IL-7 therapy to effectively improve CD8(+) T cell memory and protective immunity. These findings may have implications in the clinical use of IL-7 as an immunotherapeutic agent to bolster vaccine-induced CD8(+) T cell memory.

Low-dose mistletoe lectin-I reduces melanoma growth and spread in a scid mouse xenograft model

This study investigates the effects of mistletoe lectin-I (ML-I) on melanoma growth and spread in vivo. The human melanoma cell line MV3 was xenografted into severe combined immunodeficient mice and vehicle solution or purified ML-I was administered at 30, 150 and 500 ng per kg body weight (20 mice per group) daily. After 19 days, mice were killed, primary tumours (PTs) and lungs were dissected out, and tumour weights, number of lung metastases (LMs), number of tumour-infiltrating dendritic cells (DCs), and apoptosis rates in the melanoma cells and in the DCs were assessed. A 35% reduction of PT weight (P=0.03) and a 55% decrease in number of LMs (P=0.016) were evident for low-dose ML-I (30 ng kg(-1)) treatment but not for higher doses. Mistletoe lectin-I increased apoptosis rates in the melanoma cells of PTs at all doses, while no induction of apoptosis was noted in the LMs. Low-dose ML-I significantly increased the number of DCs infiltrating the PTs (P<0.0001) and protected DCs against apoptosis, while higher doses induced apoptosis in the DCs (P<0.01). Our results demonstrate that low-dose ML-I reduced melanoma growth and number of metastases in vivo, primarily due to immunomodulatory effects.

Identification of selectively expressed genes and antigens in CTCL

The knowledge of tumor-associated antigens is required for most types of immunotherapy and can substantially facilitate diagnosis. To identify potential tumor-associated genes expressed in cutaneous T-cell lymphoma (CTCL), we used three complementary strategies: antigens which elicit a humoral immune response in CTCL patients were detected by serological analysis of a recombinant cDNA expression library. cDNAs differentially expressed in CTCL but not peripheral blood monocytes were identified by comparative cDNA hybridization and suppression subtractive hybridization. We identified 43 genes selectively expressed by CTCL cells, that have not yet been described in the context of CTCL development, but most of which had been reported to be associated with cancer. Expression analysis by database mining and subsequently RT-PCR on selected clones confirmed their selective expression in CTCL tissues. Serological tests showed that 15 clones were recognized by sera of CTCL patients but not of healthy donors. Analysis of serological tests for 11 clones using serum antibody detection array (SADA) and 100 sera of controls and CTCL patients each revealed up to 5% reactive sera in the tumor group. The expression pattern of the detected clones and their immunogenicity demonstrates that they might be relevant for the understanding of CTCL and suggests particularly three clones, HD-CL-41 (DRAK2), HD-CL-49 (nudC) and HD-CL-12 (ZNF195) for further analysis with respect to their prognostic and therapeutic value for CTCL.

Fc gamma receptors and cancer

FcgammaRs are a family of heterogeneous molecules that play opposite roles in immune response and control the effector functions of IgG antibodies. In many cancers, IgG antibodies are produced that recognize cancer cells, form immune complexes and therefore, activate FcgammaR. The therapeutic efficacy of monoclonal IgG antibodies against hematopoietic and epithelial tumors also argue for an important role of IgG antibodies in anti-tumor defenses. Since the 1980s, a series of lines of evidence in experimental models and in humans strongly suggest that FcgammaR are involved in the therapeutic activity of monoclonal IgG antibodies by activating the cytotoxic activity of FcgammaR-positive cells such as NK cells, monocytes, macrophages and neutrophils and by increasing antigen presentation by dendritic cells. Since many cell types co-express activating and inhibitory FcgammaR, the FcgammaR-dependent effector functions of IgG anti-tumor antibodies are counterbalanced by the inhibitory FcgammaRIIB. In addition, some tumor cells express FcgammaR either constitutively, such as B cell lymphomas or ectopically, such as 40% of human metastatic melanoma. The tumor FcgammaR isoform is preferentially FcgammaRIIB, which is functional at least in human metastatic melanoma. This review summarizes these data and discusses how FcgammaRIIB expression may influence the anti-tumor immune reaction and how beneficial or deleterious this expression could be for the efficiency of therapeutics based on monoclonal anti-tumor antibodies.

An unconventional antigen translated by a novel internal ribosome entry site elicits antitumor humoral immune reactions

Self-tumor Ags that elicit antitumor immune responses in responses to IFN-alpha stimulation remain poorly defined. We screened a human testis cDNA library with sera from three polycythemia vera patients who responded to IFN-alpha and identified a novel Ag, MPD6. MPD6 belongs to the group of cryptic Ags without conventional genomic structure and is encoded by a cryptic open reading frame located in the 3'-untranslated region of myotrophin mRNA. MPD6 elicits IgG Ab responses in a subset of polycythemia vera patients, as well as patients with chronic myelogenous leukemia and prostate cancer, suggesting that it is broadly immunogenic. The expression of myotrophin-MPD6 transcripts was up-regulated in some tumor cells, but only slightly increased in K562 cells in response to IFN-alpha treatment. By using bicistronic reporter constructs, we showed that the translation of MPD6 was mediated by a novel internal ribosome entry site (IRES) upstream of the MPD6 reading frame. Furthermore, the MPD6-IRES-mediated translation, but not myotrophin-MPD6 transcription, was significantly up-regulated in response to IFN-alpha stimulation. These findings demonstrate that a novel IRES-mediated mechanism may be responsible for the translation of unconventional self-Ag MPD6 in responsive to IFN-alpha stimulation. The eliciting antitumor immune response against unconventional Ag MPD6 in patients with myeloproliferative diseases suggests MPD6 as a potential target of novel immunotherapy.

Serological analysis of human renal cell carcinoma

Serological analysis of cDNA expression libraries (SEREX) has proven to be a useful technique in the quest to elucidate the repertoire of immunogenic gene products in human cancer. We have applied the SEREX method to human renal cell carcinoma (RCC) in order to identify associated immunogenic gene products. cDNA expression libraries were prepared from a RCC tumor, a RCC cell line and human testis. The 3 libraries were screened with sera from 35 RCC patients and 15 healthy controls. Approximately 4.5 x 10(6) phage plaques were screened resulting in 234 positive clones, which corresponded to 74 different gene products. The seroreactivity toward 49 of these antigens was assessed. Seroreactivity to 21 (43%) of the antigens was similar in RCC patients and healthy controls, 9 antigens (18%) elicited antibodies more frequently and 19 antigens (39%) solely in RCC patients. In the reverse setting, reactivity of RCC patients' sera was tested against a panel of 44 previously identified "tumor-associated" antigens via the SADA (serum antibody detection array) method; 6 antigens reacted with RCC patients' and healthy donors' sera, 8 were reactive only with RCC patients' sera. From the 27 antigens identified by SEREX and SADA, which did not react with sera from healthy controls, 10 antigens reacted with a significant proportion of RCC patients' sera and 77% of RCC patients' sera reacted at least with one of these antigens. Sera from patients with non-malignant renal diseases or an autoimmune disease did not react with these 10 antigens.

The sentinel within: exploiting the immune system for cancer biomarkers

The release of proteins from tumors triggers an immune response in cancer patients. These tumor antigens arise from several mechanisms including tumor-specific alterations in protein expression, mutation, folding, degradation, or intracellular localization. Responses to most tumor antigens are rarely observed in healthy individuals, making the response itself a biomarker that betrays the presence of underlying cancer. Antibody immune responses show promise as clinical biomarkers because antibodies have long half-lives in serum, are easy to measure, and are stable in blood samples. However, our understanding of the specificity and the impact of the immune response in early stages of cancer is limited. The immune response to cancer, whether endogenous or driven by vaccines, involves highly specific T lymphocytes (which target tumor-derived peptides bound to self-MHC proteins) and B lymphocytes (which generate antibodies to tumor-derived proteins). T cell target antigens have been identified either by expression cloning from tumor cDNA libraries, or by prediction based on patterns of antigen expression ("reverse immunology"). B cell targets have been similarly identified using the antibodies in patient sera to screen cDNA libraries derived from tumor cell lines. This review focuses on the application of recent advances in proteomics for the identification of tumor antigens. These advances are opening the door for targeted vaccine development, and for using immune response signatures as biomarkers for cancer diagnosis and monitoring.

Cancer/testis antigens and gametogenesis: a review and "brain-storming" session

Genes expressed both in normal testis and in malignancies (Cancer/ Testis associated genes - CTA) have become the most extensively studied antigen group in the field of tumour immunology. Despite this, many fundamentally important questions remain unanswered: what is the connection between germ-cell specific genes and tumours? Is the expression of these genes yet another proof for the importance of genome destabilisation in the process of tumorigenesis?, or maybe activation of these genes is not quite random but instead related to some programme giving tumours a survival advantage?This review collates most of the recent information available about CTAs expression, function, and regulation. The data suggests a programme related to ontogenesis, mostly to gametogenesis. In the "brain-storming" part, facts in conflict with the hypothesis of random CTA gene activation are discussed. We propose a programme borrowed from organisms phylogenetically much older than humans, which existed before the differentiation of sexes. It is a programme that has served as a life cycle with prominent ploidy changes, and from which, as we know, the germ-cell ploidy cycle - meiosis - has evolved. Further work may show whether this hypothesis can lead to a novel anti-tumour strategy.

Analysis of the autoantibody repertoire in Burkitt's lymphoma patients: frequent response against the transcription factor ATF-2

In the last few years, serological identification of tumour-associated antigens (TAAs) by recombinant cDNA expression cloning (SEREX) has enabled the mapping of humoral immune responses against TAAs in various types of cancer. The present paper describes the application of SEREX to Burkitt's lymphoma (BL), a malignancy not previously characterized by SEREX. By using a cDNA library from a BL cell line that does not express IgG, technical difficulties related to background immunoglobulin clones were overcome. Screening with sera from three BL patients revealed immunoreactivity against seven different gene products, six of which represent known human genes. Five proteins had previously been characterized by SEREX in other malignancies or identified as targets of autoantibodies in autoimmune disease. Seroreactivity against ATF-2, a member of the AP-1 transcription factor family, was validated by enzyme-linked immunosorbent assay (ELISA) and Western blot analysis using recombinant ATF-2 protein. Autoantibody responses against ATF-2 were detected by ELISA in 6 of 8 BL patients, compared with 6 of 13 patients with T-cell non-Hodgkin's lymphoma (T-NHL), 5 of 23 patients with follicular lymphoma and 2 of 27 diffuse large B-cell lymphoma patients. In contrast, reactivity was found in only 1 of 50 healthy volunteers. Next, we showed by immunohistochemistry that the activated form of ATF2 (ATF-2pp) was highly expressed in six different BL samples. We conclude that the SEREX approach with a B-cell cDNA source is applicable in NHL. Furthermore, we identified genes with possible involvement in the pathogenesis of BL using this technique.