Development Of Antitumor Vaccines Research Articles

Proteolytically-cleaved Fragments of Cell-surface Proteins from Live Tumor Cells Stimulate Anti-tumor Immune Response In vitro

Antigens expressed on the surface of cancer cells are accessible targets for both humoral and cell-mediated immune responses, and are therefore potential candidates for vaccine development. Treating surface of live human breast adenocarcinoma cells (MCF-7) with trypsin yields a digest that contains 0.7% of total cell protein. Despite this difference, the trypsin digest stimulates in cytotoxicity assays anti-tumor response which kills 10-40% more cancer cells than those stimulated with cells themselves. From these results, we concluded that trypsin digest obtained from live cancer cells contains the essential antigens to induce an immune-mediated anti-tumor effect, and therefore, is candidate for anti-tumor vaccine development.

The Italian Network for Tumor Biotherapy (NIBIT). Sharing Visions, Goals and Efforts at European Level

In the context of the Scientific Week 2008 of the Organisation of the European Cancer Institutes, the Italian Network for Tumor Biotherapy (NIBIT), within its initiatives sponsored by Alleanza Contro il Cancro, the Italian Network of Comprehensive Cancer Centers has contributed to organize the Workshop of the European Networks for bio-immunotherapy of tumors. Representatives from the Nordic Center of Excellence for the Development of Anti-Tumor Vaccines (Sweden), the German Network of Immunotherapy of Tumors (Germany), the Biotherapy Development Association and NIBIT gathered to present their organization and ongoing scientific activities, as well as to identify common strategies and shared efforts to push the field of cancer bio-immunotherapy forward at a European level. This article briefly summarizes the history and objectives of NIBIT, along with the actions so far taken by the Network.

Immunotherapy opportunities in ovarian cancer

Ovarian cancer is responsible for the majority of gynecologic cancer deaths and despite the highest standard of multimodality therapy with surgery and cytotoxic chemotherapy, long-term survival remains low. With compelling evidence that epithelial ovarian cancer is an immunogenic tumor capable of stimulating an antitumor immune response, renewed efforts to develop immune therapies to augment the efficacy of traditional therapies are underway. Current immunotherapies focus on varied modes of antitumor vaccine development, particularly with the use of dendritic cell vaccines, effective methods for adoptive T-cell transfer and combinatorial approaches with immune modulatory therapy subverting natural tolerance mechanisms or boosting effector mechanisms. Additional combinatorial approaches include the use of cytokines and/or chemotherapy with immune therapy.

The oncofetal protein, 5T4, is a suitable target for antibody-guided anti-cancer chemotherapy with calicheamicin

The oncofetal protein, 5T4, is a tumor-associated protein displayed on the cell membrane of various carcinomas. This molecule is a promising target for anti-tumor vaccine development and for targeted therapy with staphylococcus exotoxin. The potential use of 5T4 as a target for antibody-guided chemotherapy has not been demonstrated. We report oncolytic efficacy and selectivity in vitro and in vivo with immuno-conjugates of calicheamicin (CM) and the anti-5T4 antibody, H8. CM is a potent cytotoxic drug that causes double strand breaks in DNA. Conjugates of CM and H8 were constructed with acid-labile as well as acid-stabile linkers. In vitro, when applied to monolayers of 5T4(+) cells, CM-conjugates targeting 5T4 were consistently more toxic than either free drug or a non-binding control CM-conjugate. This difference was less pronounced on 5T4-deficient cells. In vivo, four 5T4-positive subcutaneous tumor models were treated with conjugates. Efficacy was demonstrated by reduction of tumor growth relative to controls treated with drug vehicle. To evidence selectivity, the efficacy of the anti-5T4 conjugates was compared to the efficacy of H8, a mixture of H8 and calicheamicin, calicheamicin alone or calicheamicin conjugated to the anti-CD33 antibody, hP67.6. In addition, the efficacy and selectivity of an acid-labile conjugate of H8 was evaluated in an orthotopic model for 5T4(+) lung cancer. Increased survival following treatment was used as a parameter of efficacy. Calicheamicin conjugates of H8 were effective and selective in all the examined tumor models. Differences in efficacy between the acid-labile and acid-stabile conjugates depended on the investigated tumor model.

Synthetic Glycopeptides from the Mucin Family as Potential Tools in Cancer Immunotherapy

Compared to glycoproteins of healthy cells, glycoproteins of tumor cells are often aberrantly glycosylated. Thus, glycopeptide fragments of surface glycoproteins of tumor cells are of interest as tumor-associated antigens for the distinction between normal and tumor cells. Cancer immunotherapy directed at selectively targeting these tumor-associated glycoprotein structure alterations--deficient glycosylation and, thus, exposure of peptide epitopes which are masked in normal cells--is considered a promising approach for the treatment of cancer. For this purpose, glycoproteins from the mucin family are of particular interest. Mucins belong to a class of heavily O-glycosylated, high-molecular weight glycoproteins present on the surface of many epithelial cells. The mucin core protein consists of numerous tandem repeats rich in serine, threonine and proline. In their tumor-associated forms, epithelial mucins carry cryptic saccharide structures such as T(N)-, T-, sialyl-T(N)- and sialyl-T antigens and more complex oligosaccharides (e.g. Lewis(y)). In contrast to glycoproteins isolated from natural sources, synthetic glycopeptides can be obtained in high purity and with exactly defined structure. In this review, methodologies for the synthesis of mucin-type glycopeptides containing complex tumor-associated antigen structures are described. Due to the low immunogenicity often exhibited by synthetic tumor-associated glycopeptide antigens, their conjugation to carrier proteins or suitable T-cell epitopes is essential for the development of anti-tumor vaccines. The results of immunological evaluations of synthetic (glyco)peptides and oligosaccharides are described. Some of these synthetic vaccines show promising activities inducing proliferation of T-cells and cytotoxic T-cell responses.

CpG oligodeoxynucleotides activate dendritic cells in vivo and induce a functional and protective vaccine immunity against a TERT derived modified cryptic MHC class I-restricted epitope

The use of synthetic peptides derived from tumor-associated Ags is attractive for the development of antitumoral vaccines as far as strong adjuvants are found to render them immunogenic. Here, we investigated the possibility to enhance the CD8 response against the human and mouse shared TERT 572Y HLA-A*0201 restricted modified cryptic peptide by using ODN-CpG as adjuvant. Humanized transgenic mice were immunized with the TERT 572Y modified cryptic peptide in the presence of ODN-CpG and compared to mice immunized in IFA. By contrast with IFA, we first showed that, in vivo, ODN-CpG leads to the recruitment of dendritic cells in the lymph nodes draining the injection site. Those cells and especially the CD11c + CD11b − CD8a + lymphoid and the CD11c + B220 + plasmacytoid dendritic cells were activated as shown by up-regulation of CD40 at their cell surface. Immunization against TERT 572Y peptide in the presence of ODN-CpG rather than IFA led to a strong CD8 response and can delayed mortality in an induced tumor model. Study of the CD8 response obtained after antigenic challenge suggested that a functional memory response is induced upon vaccination with ODN-CpG. Thus, MHC class I-restricted epitope in combination of ODN-CpG is a promising and rather simple cancer vaccine formulation.

Candidate epitope identification using peptide property models: application to cancer immunotherapy

Peptides derived from pathogens or tumors are selectively presented by the major histocompatibility complex proteins (MHC) to the T lymphocytes. Antigenic peptide–MHC complexes on the cell surface are specifically recognized by T cells and, in conjunction with co-factor interactions, can activate the T cells to initiate the necessary immune response against the target cells. Peptides that are capable of binding to multiple MHC molecules are potential T cell epitopes for diverse human populations that may be useful in vaccine design. Bioinformatical approaches to predict MHC binding peptides can facilitate the resource-consuming effort of T cell epitope identification. We describe a new method for predicting MHC binding based on peptide property models constructed using biophysical parameters of the constituent amino acids and a training set of known binders. The models can be applied to development of anti-tumor vaccines by scanning proteins over-expressed in cancer cells for peptides that bind to a variety of MHC molecules. The complete algorithm is described and illustrated in the context of identifying candidate T cell epitopes for melanomas and breast cancers. We analyzed MART-1, S-100, MBP, and CD63 for melanoma and p53, MUC1, cyclin B1, HER-2/neu, and CEA for breast cancer. In general, proteins over-expressed in cancer cells may be identified using DNA microarray expression profiling. Comparisons of model predictions with available experimental data were assessed. The candidate epitopes identified by such a computational approach must be evaluated experimentally but the approach can provide an efficient and focused strategy for anti-cancer immunotherapy development.

Role of IL-13 in regulation of anti-tumor immunity and tumor growth.

Major mediators of anti-tumor immunity are CD4(+) T(h)1 cells and CD8(+) cytotoxic T lymphocytes (CTLs). In tumor-bearing animals, the T(h)1- and CTL-mediated anti-tumor immunity is down-regulated in multiple ways. Better understanding of negative regulatory pathways of tumor immunity is crucial for the development of anti-tumor vaccines and immunotherapies. Since immune deviation toward T(h)2 suppresses T(h)1 development, it has been thought that induction affecting a T(h)2 immune response is one of the mechanisms that down-regulate effective tumor immune responses. Recent studies using T(h)2-deficient signal transducer and activator (Stat6) KO mice demonstrated that this hypothesis was the case. IL-13 is one of the T(h)2 cytokines that has very similar features to IL-4 through sharing some receptor components and Stat6 signal transduction. It has been thought that IL-13 is not as critical for immune deviation as IL-4 since it cannot directly act on T cells. However, recent studies of IL-13 reveal that this cytokine plays a critical role in many aspects of immune regulation. Studies from our lab and others indicate that IL-13 is central to a novel immunoregulatory pathway in which NKT cells suppress tumor immunosurveillance. Here we will describe biological properties and functions of IL-13, its role in the negative regulation of anti-tumor immunity, and effects of IL-13 on tumor cells themselves.

Synthetic Glycopeptides for the Development of Antitumor Vaccines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Insertion of interleukin-2 ( IL-2) and interleukin-12 ( IL-12) genes into vaccinia virus results in effective anti-tumor responses without toxicity

Identification of novel tumor-associated antigens (TAA) capable of eliciting T-cell responses has renewed interest in the development of anti-tumor vaccines. The insertion of genes encoding specific TAA into a vaccinia virus (rVV) is one approach to vaccination since large amounts of foreign DNA can be stably integrated into the poxvirus genome. Recent reports have documented an increased therapeutic effectiveness of poxvirus-based vaccines when additional treatment with cytokines, such as interleukin-2 (IL-2) or interleukin-12 (IL-12) were used, but the combination of these cytokines as adjuvants for a rVV encoding TAA have not been previously reported. The combination of IL-2 and IL-12 at single regimen systemic doses was toxic and sometimes fatal, manifesting largely as segmental epithelial apoptosis of the large bowel. To explore the local delivery of both cytokines to the site of vaccination, the genes encoding IL-2 and IL-12 were inserted into vaccinia virus along with a model tumor antigen gene. This construct contained five heterologous genes: LacZ (the model antigen), gpt (reporter gene), IL-2, and the two IL-12 subunit genes ( p35 and p40). Treatment with this recombinant virus resulted in a reduced number of pulmonary metastases, improved survival, and minimal toxicity in a murine tumor model. The use of vaccinia virus for the insertion of other heterologous gene combinations may provide a powerful and less toxic approach for novel vaccination strategies in the treatment and prevention of cancer.

A novel approach for modifying tumor cell-derived plasma membrane vesicles to contain encapsulated IL-2 and engrafted costimulatory molecules for use in tumor immunotherapy.

The genetic modification of tumor cells and delivery of cytokines have been proposed as useful strategies in the development of anti-tumor vaccines; however, a number of factors limit their use in clinical settings. To facilitate vaccine development, we explored the possibility of modifying plasma membrane vesicles (PMV) by using a novel chelator lipid, nitrilotriacetic acid ditetradecylamine (NTA-DTDA). Our analyses by flow cytometry show that NTA-DTDA can be incorporated into PMV prepared from murine P815 mastocytoma and that the incorporated NTA-DTDA permits anchoring or "engraftment" onto the vesicle surface of hexahistidine-tagged proteins such as recombinant forms of the costimulatory molecules B7.1 and CD40. The engrafted PMV also can incorporate and deliver the immunostimulatory cytokine Interleukin-2 (IL-2). Our results show that modified PMV derived from P815 cells bind the murine T cell clone D10 in a receptor-ligand dependent manner, inducing cell adhesion and promoting cell survival in vitro. The modified PMV can bind syngeneic T cells, stimulating T cell proliferation and cytotoxic T cell responses. Moreover, when used as vaccines in syngeneic animals, the modified vesicles induce significant protection against challenge with the native P815 tumor. The results indicate that PMV modified by engraftment of recombinant forms of B7.1 and CD40 and incorporation of IL-2 can be used to modulate immune responses, which provides a novel approach for the development of anti-tumor vaccines and cancer immunotherapies.

Immunotherapy directed against α-fetoprotein results in autoimmune liver disease during liver regeneration in mice

Background & Aims: Priming immune responses against α-fetoprotein (AFP) highly expressed in the majority of hepatocellular carcinomas results in significant antitumoral T-cell responses. Liver regeneration in humans and mice, however, is also associated with increased AFP expression. Therefore, we evaluated the risk of AFP-directed immunotherapeutic approaches to induce autoimmunity against the regenerating liver. Methods: Mice were immunized with DNA encoding mouse AFP. For induction of liver regeneration, partial hepatectomy was performed and mice were monitored by serial histopathologic examinations and measurements of serum ALT activities (U/L), and by determination of the kinetics of AFP-specific T-cell responses. Results: Livers of AFP immune mice without partial hepatectomy were characterized by minor lymphocytic infiltrations without transaminase elevations. By contrast, a significant hepatocyte damage was observed in regenerating liver that correlated well with the number of AFP-specific CD8+ T cells, the activity of liver regeneration, and the level of AFP synthesis. Autoimmune liver damage was mediated by CD4+ T cell–dependent CD8+ cytotoxic T lymphocytes. Conclusions: These results show that priming of T-cell responses against shared tumor-specific self antigens may be accompanied by induction of autoimmunity dependent on the level of expression of the self antigen and have important implications for the development of antitumoral vaccines targeted against antigens that are not strictly tumor-specific.GASTROENTEROLOGY 2001;121:931-939

Towards the Development of Antitumor Vaccines: A Synthetic Conjugate of a Tumor-Associated MUC1 Glycopeptide Antigen and a Tetanus Toxin Epitope.

Proliferation of cytotoxic T-cells, a prerequisite for the development of antitumor vaccines, was induced by 1, but not by its partial structures A and B. The conjugate 1 containing a tumor-associated Sialyl-TN -MUC-1 glycopeptide antigen A and a T-cell epitope B of tetanus toxin was synthesized by fragment condensation on a solid phase.

Glycosphingolipid antigens and cancer therapy.

Specific types of glycosphingolipid (GSL), which are chemically detectable in normal cells, are more highly expressed in tumors. The high level of expression on the surfaces of tumor cells causes an antibody response to these GSLs, which can therefore be described as tumor-associated antigens. Some of these GSLs have been shown to be adhesion molecules involved in tumor cell metastasis, and to be modulators of signal transduction controlling tumor cell growth and motility. Tumor-associated GSL antigens have been used in the development of antitumor vaccines. GSLs and sphingolipids involved in adhesion and signaling are therefore targets for cancer therapy.

Curing metastases? Gene and peptide therapy.

Major histocompatibility complex (MHC) molecules are peptide receptors. Their function is to collect peptides inside the cell and transport them to the cell surface, where the complex of peptide and MHC molecule may be recognized by T lymphocytes (Rammensee et al. 1993). In normal cells MHC-associated peptides are derived from normal, self proteins. During their differentiation, T cells become tolerant — by elimination or inactivation (anergy) — to complexes of self MHC and self peptides (Von Boehmer 1992). Thus when new peptides derived from infectious agents or changed self proteins occur later, these can be recognized by T cells (Zinkernagel and Dohenty 1974). However, overexpressed, aberrantly expressed, and even normal self proteins can induce T cell responses under conditions which revert anergy (Nanda and Sercarz 1995). Since the specific immune response is regulated by T cells, the trimolecular complex of T cell receptor (TCR), MHC molecule, and peptides serves as a control switch for the immune system. Control of tumor growth and tumor dissemination by the immune system, particularly by the cellular immune system, is the basis for development of antitumor vaccines (Foley 1953; Prehn and Main 1957; Klein et al. 1960; Old et al. 1962). The role MHC molecules and their associated peptides play in tumor contol is important for development of targeted antigen-specific vaccines for cancer therapy.KeywordsMajor Histocompatibility ComplexHuman Leukocyte AntigenMajor Histocompatibility Complex ClassHuman Leukocyte Antigen ClassMajor Histocompatibility Complex MoleculeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.