Identification and characterization of a HER-2/neu epitope as a potential target for cancer immunotherapy (original) (raw)
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Immunogenic HER-2/neu peptides as tumor vaccines
Cancer Immunology, Immunotherapy, 2006
During the last decade, a large number of tumor-associated antigens (TAA) have been identified, which can be recognized by T cells. This has led to renewed interest in the use of active immunization as a modality for the treatment of cancer. HER-2/neu is a 185-KDa receptor-like glycoprotein that is overexpressed by a variety of tumors including breast, ovarian, lung, prostate and colorectal carcinomata. Several immunogenic HER-2/neu peptides recognized by cytotoxic T lymphocytes (CTL) or helper T lymphocytes (TH) have been identified thus far. Patients with HER-2/ neu over-expressing cancers exhibit increased frequencies of peripheral blood T cells recognizing immunogenic HER-2/neu peptides. Various protocols for generating T cell-mediated immune responses specific for HER-2/neu peptides have been examined in pre-clinical models or in clinical trials. Vaccination studies in animals utilizing HER-2/neu peptides have been successful in eliminating tumor growth. In humans, however, although immunological responses have been detected against the peptides used for vaccination, no clinical responses have been described. Because HER-2/neu is a self-antigen, functional immune responses against it may be limited through tolerance mechanisms. Therefore, it would be interesting to determine whether abrogation of tolerance to HER-2/neu using appropriate adjuvants and/or peptide analogs may lead to the development of immune responses to HER-2/neu epitopes that can be of rele-vance to cancer immunotherapy. Vaccine preparations containing mixtures of HER-2/neu peptides and peptide from other tumor-related antigens might also enhance efficacy of therapeutic vaccination.
International Journal of Cancer, 2007
The Ii-Key fragment from the MHC class II-associated invariant chain (or Ii protein) has been shown to facilitate direct charging of MHC class II epitopes to the peptide binding groove. The purpose of the present study was to test the potential of a series of Ii-Key/ HER-2/neu(776-790) hybrid peptides to generate increased frequencies of peptide-specific CD4 1 T cells over the native peptide in mice transgenic (Tg) for a chimeric human mouse class II molecule (DR4-IE) (H-2 b ) as well as their antitumor potency. Following in vivo priming, such hybrid peptides induced increased proliferation and frequencies of IFN-c producing CD4 1 T cells in response to either syngeneic dendritic cells pulsed with native peptide, or HLA-DR4 1 human tumor cell lines expressing HER-2/neu. Hybrid peptides were more stable in an off-rate kinetics assay compared to the native peptide. In addition, antigen-specific CD4 1 T cells from hybrid peptide immunized DR4-IE Tg mice synergized with HER-2/neu(435-443)-specific CD8 1 T cells from HLA-A2.1 Tg HHD (H-2 b ) mice in producing antitumor immunity into SCID mice xenografted with the HER-2/neu 1 , HLA-A2.1 1 and HLA-DR4 1 FM3 human melanoma cell line. High proportions of these adoptively transferred HER-2/neu peptide-specific CD4 1 and CD8 1 T cells infiltrated FM3-induced tumors (tumor infiltrating lymphocytes; TIL) in SCID mice. CD8 1 TIL exhibited long-lasting antitumor activity when cotransferred with CD4 1 TIL, inducing regression of FM3 tumors in a group of untreated, tumor-bearing SCID mice, following adoptive transfer. Our data show that Ii-Key modified HER-2/neu(776-790) hybrid peptides are sufficiently potent to provide antigen-specific CD4 1 T H cells with therapeutic antitumor activity. ' 2007 Wiley-Liss, Inc.
Cancer Immunology, Immunotherapy, 2006
We have demonstrated that coupling an immunoregulatory segment of the MHC class IIassociated invariant chain (Ii), the Ii-Key peptide, to a promiscuous MHC class II epitope signiWcantly enhances its presentation to CD4+ T cells. Here, a series of homologous Ii-Key/HER-2/neu(776-790) hybrid peptides, varying systematically in the length of the epitope(s)-containing segment, are signiWcantly more potent than the native peptide in assays using T cells from patients with various types of tumors overexpressing HER-2/neu. In particular, priming normal donor and patient PBMCs with Ii-Key hybrid peptides enhances recognition of the native peptide either pulsed onto autologous dendritic cells (DCs) or naturally presented by IFN-treated autologous tumor cells. Moreover, patient-derived CD4+ T cells primed with the hybrid peptides provide a signiWcantly stronger helper eVect to autologous CD8+ T cells speciWc for the HER-2/neu(435-443) CTL epitope, as illustrated by either IFN-ELISPOT assays or speciWc autologous tumor cell lysis. Hybrid peptide-speciWc CD4+ T cells strongly enhanced the antitumor eYcacy of HER-2/neu(435-443) peptide-speciWc CTL in the therapy of xenografted SCID mice inoculated with HER-2/neu overexpressing human tumor cell lines. Our data indicate that the promiscuously presented vaccine peptide HER-2/neu(776-790) is amenable to Ii-Keyenhancing eVects and supports the therapeutic potential of vaccinating patients with HER-2/neu+ tumors with such Ii-Key/HER-2/neu(776-790) hybrid peptides. Keywords Ii-Key hybrid peptides • HER-2/neu peptides • Cancer vaccines • T helper cells • CTL Nectaria N. Sotiriadou and Nikoletta L. Kallinteris have contributed equally to the work.
The Journal of Immunology, 2008
HER-2/neu oncoprotein is overexpressed in a variety of human tumors and is associated with aggressive disease. Immunogenic HER-2/neu CTL epitopes have been used as vaccines for the treatment of HER-2/neu positive malignancies with limited success. By applying prediction algorithms for MHC class I ligands and proteosomal cleavages, in this study, we describe the identification of HER-2/neu decamer LIAHNQVRQV spanning residues 85-94 (HER-2(10 85 )). HER-2(10 85 ) proved to bind with high affinity to HLA-A2.1 and was stable for 4 h in an off-kinetics assay. This peptide was immunogenic in HLA-A2.1 transgenic (HHD) mice inducing peptide-specific CTL, which responded to tumor cell lines of various origin coexpressing human HER-2/neu and HLA-A2.1. This demonstrates that HER-2(10 85 ) is naturally processed from endogenous HER-2/neu. Five of sixteen HER-2/neu ؉ HLA-A2.1 ؉ breast cancer patients analyzed had HER-2(10 85 )-reactive T cells ranging from 0.35-0.70% of CD8 ؉ T cells. Depletion of T regulatory cells from PBMC enabled the rapid expansion of HLA-A2.1/HER-2(10 85 )pentamer ؉ /CD8 ؉ cells (PENT ؉ / CD8 ؉ ), whereas significantly lower numbers of CTL could be generated from unfractionated PBMC. HER-2(10 85 )-specific human CTL recognized the HER-2/neu ؉ HLA-A2.1 ؉ tumor cell line SKBR3.A2, as determined by IFN-␥ intracellular staining and in the high sensitivity CD107␣ degranulation assay. Finally, HER-2(10 85 ) significantly prolonged the survival of HHD mice inoculated with the transplantable ALC.A2.1.HER tumor both in prophylactic and therapeutic settings. These data demonstrate that HER-2(10 85 ) is an immunogenic peptide, capable of eliciting CD8-mediated responses in vitro and in vivo, providing the platform for further exploitation of HER-2(10 85 ) as a possible target for anticancer immunotherapy.
HER-2/neu Cancer Vaccines: Present Status and Future Prospects
International Journal of Peptide Research and Therapeutics, 2006
Immunotherapeutic approaches to cancer should focus on novel undertakings that modulate immune responses by synergistic enhancement of anti-tumor immunological parameters. Cancer vaccines should preferably be composed of multiple defined tumor antigen specific Band T-cell epitopes. The main focus of this article is to briefly review the present status of Her-2/neu vaccine strategies and to describe the innovative strategies developed in my laboratory for a vaccine against HER-2/neu (ErbB-2) with emphasis on the humoral arm of the immune response. Elucidating the underlining mechanisms of anti-tumor effects elicited by peptide vaccines against a self-protein is a requirement for developing an immunotherapeutic strategy that might be effective in human cancer vaccines. Our approach entails the identification of biologically relevant epitopes, establishing relevant in vitro assays for monitoring vaccine efficacy, devising strategies to engineer conformationally dependent sequences, developing highly immunogenic vaccines for an outbred population and delivering the immunogen/vaccine in a safe and efficacious vehicle, utilizing transgenic animal models for assessing tumor development, and developing challenge models using transplantable tumors to study efficacy of vaccine constructs. We have developed a multi-HER-2/neu B-cell epitope approach and shown in preclinical studies that immunization with a combination of two B-cell epitope was more effective in preventing mammary tumors than a single epitope. We have translated that work to the clinic (OSU 0105) in an FDA approved, NCI sponsored ''Phase 1 Active Immunotherapy trial with Chimeric and Multi-epitope based peptide vaccine targeting HER-2 oncoprotein and nor-MDP adjuvant in patients with metastatic and/or recurrent solid tumors'' at the James Cancer Hospital at the Ohio State University. The correlation between overexpression of HER-2/neu and up-regulation of VEGF has been demonstrated in breast cancer patients. Thus, blocking angiogenesis is an attractive strategy to inhibit tumor growth, invasion, and metastasis. The hypothesis that combination of anti-angiogenic therapy and tumor immunotherapy of cancer may be synergistic is an important future goal. In this review, I will discuss insights into our preclinical studies that might aid in the design of the next generation of cancer vaccines and become an integrated component of prophylactic/preventive and therapeutic approach.
Cancer Immunology Immunotherapy, 2002
HER-2/neu peptides recognized in the context of HLA-DR molecules by CD4+ Th lymphocytes on antigen-presenting cells have been identified. In this report, we demonstrate for the first time that HER-2/neu helper epitopes are also expressed on the surface of metastatic breast, colorectal and pancreatic carcinomas. Peripheral blood mononuclear cells from an HLA-DR4 healthy donor were used to induce HER-2/neu peptide-specific CD4+ T cell clones by in vitro immunization with HER-2/neu peptide (884–899)-pulsed autologous dendritic cells (DCs). Strong proliferation and significant levels of IFN-γ were induced by the CD4+ T cell clones in response to specific stimulation with autologous DCs loaded with HER-2(884–899). Furthermore, these clones also recognized HER-2/neu+ tumor cell lines, and tumor cells from breast, colorectal and pancreatic adenocarcinomas induced to express HLA-DR4, but also the HLA-DR4+ melanoma cell line FM3 transfected to express HER-2/neu. The recognition of tumor cells was strongly inhibited by an anti-HLA-DR mAb. Taken altogether, we provide novel information for the role of HER-2(884–899) as a naturally processed epitope expressed by breast, colorectal and pancreatic carcinomas and the capacity of HER-2/neu protein to follow the endogenous class II processing pathway. Our results suggest that HER-2(884–899) might be attractive for broadly applicable vaccines and may prove useful for adoptive immunotherapy designed for breast, colorectal and pancreatic carcinomas.
Cancer Immunology, …, 2007
We have demonstrated that coupling an immunoregulatory segment of the MHC class IIassociated invariant chain (Ii), the Ii-Key peptide, to a promiscuous MHC class II epitope signiWcantly enhances its presentation to CD4+ T cells. Here, a series of homologous Ii-Key/HER-2/neu(776-790) hybrid peptides, varying systematically in the length of the epitope(s)-containing segment, are signiWcantly more potent than the native peptide in assays using T cells from patients with various types of tumors overexpressing HER-2/neu. In particular, priming normal donor and patient PBMCs with Ii-Key hybrid peptides enhances recognition of the native peptide either pulsed onto autologous dendritic cells (DCs) or naturally presented by IFN-treated autologous tumor cells. Moreover, patient-derived CD4+ T cells primed with the hybrid peptides provide a signiWcantly stronger helper eVect to autologous CD8+ T cells speciWc for the HER-2/neu(435-443) CTL epitope, as illustrated by either IFN-ELISPOT assays or speciWc autologous tumor cell lysis. Hybrid peptide-speciWc CD4+ T cells strongly enhanced the antitumor eYcacy of HER-2/neu(435-443) peptide-speciWc CTL in the therapy of xenografted SCID mice inoculated with HER-2/neu overexpressing human tumor cell lines. Our data indicate that the promiscuously presented vaccine peptide HER-2/neu(776-790) is amenable to Ii-Keyenhancing eVects and supports the therapeutic potential of vaccinating patients with HER-2/neu+ tumors with such Ii-Key/HER-2/neu(776-790) hybrid peptides. Keywords Ii-Key hybrid peptides • HER-2/neu peptides • Cancer vaccines • T helper cells • CTL Nectaria N. Sotiriadou and Nikoletta L. Kallinteris have contributed equally to the work.
Immunobiology of HER-2/ neu oncoprotein and its potential application in cancer immunotherapy
Cancer Immunology, Immunotherapy, 2004
HER-2/neu (also known as HER2 or c-erb-B2) is a 185-kDa protein receptor with tyrosine kinase activity and extensive homology to the epidermal growth factor (EGF) receptor. HER-2/neu is expressed in many epithelial tumors and known to be overexpressed in approximately 20-25% of all ovarian and breast cancers, 35-45% of all pancreatic adenocarcinomas, and up to 90% of colorectal carcinomas. HER-2/neu overexpression represents a marker of poor prognosis. HER-2/ neu-positive tumor cells are potentially good targets for tumor-reactive cytotoxic T lymphocytes which have been utilized in immunotherapeutic trials. In addition, the ''humanized'' monoclonal antibody Herceptin has been tested in several clinical trials and proved to be an effective adjuvant therapy for HER-2/neu-positive breast and ovarian cancers. Vaccinations aiming at generating T-cell responses are being examined in both experimental and clinical trials. Natural immunity at the level of T and B cells has been observed in patients with HER-2/neu-positive tumors confirming the immunogenicity of HER-2/neu and encouraging vaccination trials with HER-2 protein-derived subunits or synthetic peptides. This review summarizes recent data from patients with various types of HER-2/neu-overexpressing cancers carrying different HLA alleles and exhibiting preexistent immunity to HER-2/neu-derived synthetic peptides. It also discusses potential advantages of the various vaccination approaches to immunotherapy targeting the HER-2/neu molecule.
Antitumor vaccination with HER-2-derived recombinant antigens
International Journal of Cancer, 2002
Certain types of malignant tumors overexpress HER-2, a transmembrane glycoprotein of the class I receptor tyrosine kinase erbB family. To develop an effective HER-2 vaccine for the selective immunotherapy of these malignancies, we have genetically engineered fusion proteins containing portions of extra-and intracellular HER-2 domains. Activated dendritic cells (DC) cocultured with these novel antigens (Ag) could induce potent responses of Ag-specific T-cell lines in vitro and a protection against HER-2-expressing tumor in vivo. The protective capabilities of HER-2-derived fusion proteins correlated with the efficiency of their presentation to Ag-specific T-cell hybridomas. The most effective Ag contained GM-CSF, the presence of which facilitated their internalization by antigen-presenting cells (APC) in a receptor-mediated manner.