TAA polyepitope DNA-based vaccines: a potential tool for cancer therapy.

DNA-based cancer vaccines represent an attractive strategy for inducing immunity to tumor associated antigens (TAAs) in cancer patients. The demonstration that the delivery of a recombinant plasmid encoding epitopes can lead to epitope production, processing, and presentation to CD8+ T-lymphocytes, and the advantage of using a single DNA construct encoding multiple epitopes of one or more TAAs to elicit a broad spectrum of cytotoxic T-lymphocytes has encouraged the development of a variety of strategies aimed at increasing immunogenicity of TAA polyepitope DNA-based vaccines. The polyepitope DNA-based cancer vaccine approach can (a) circumvent the variability of peptide presentation by tumor cells, (b) allow the introduction in the plasmid construct of multiple immunogenic epitopes including heteroclitic epitope versions, and (c) permit to enroll patients with different major histocompatibility complex (MHC) haplotypes. This review will discuss the rationale for using the TAA polyepitope DNA-based vaccination strategy and recent results corroborating the usefulness of DNA encoding polyepitope vaccines as a potential tool for cancer therapy.

Local delivery of recombinant vaccinia virus encoding for neu counteracts growth of mammary tumors more efficiently than systemic delivery in neu transgenic mice.

Recombinant vaccinia virus has been widely employed as a cancer vaccine in several clinical trials. In this study we explored, employing BALB/c mice transgenic for the rat neu oncogene, the ability of the recombinant vaccinia virus neu (rV-neuT) vaccine to inhibit growth of neu+ mammary carcinomas and whether the efficacy of vaccination was dependent on: (a) carcinogenesis stage at which the vaccination was initiated; (b) number of vaccinations and (c) route of delivery (systemic vs. local). BALB-neuT mice were vaccinated one, two and three times by subcutaneous (s.c.) and intramammary gland (im.g.) injection with rV-neuT or V-wt (wild-type vaccinia virus) starting at the stage in which mouse mammary gland displays atypical hyperplasia, carcinoma in situ or invasive carcinoma. We demonstrated that vaccination using rV-neuT was more effective when started at an earlier stage of mammary carcinogenesis and after three vaccinations. The im.g. vaccination was more effective than the s.c. vaccination in inhibiting mammary carcinogenesis, eliciting anti-Neu antibodies, increasing anti-Neu IgG2a/G3 isotypes and inducing antibodies able to trigger mammary tumor cells apoptosis and antibody-dependent cellular cytotoxicity. The better protective ability of rV-neuT im.g. vaccination was associated with its capacity to induce a superior degree of in vivo mammary cancer cells apoptosis. Our research suggests that intratumoral vaccination using recombinant vaccinia virus could be employed to increase the activity of a genetic cancer vaccine. This study may have important implications for the design of cancer vaccine protocols for the treatment of breast cancer and of accessible tumors using recombinant vaccinia virus.

Long-lasting tissue inflammatory processes trigger autoimmune responses to extracellular matrix molecules.

Extracellular matrix (ECM) remodeling is strongly favored by the conditions occurring in the inflammatory microenvironment and can lead to pathogenic reactions directed toward the ECM itself. Several reports have described autoimmune responses to ECM molecules in patients with inflammatory diseases whose pathogenesis is not primarily related to ECM autoimmunity. This review will focus on the molecular interplay that governs ECM remodeling during tissue inflammation and will discuss how chronic inflammation can act as a driving force for the induction of autoimmune responses to ECM components as well as how the elicited autoimmunity can sustain local or induce distant tissue damage.

A polyepitope DNA vaccine targeted to Her-2/ErbB-2 elicits a broad range of human and murine CTL effectors to protect against tumor challenge.

A cDNA vaccine (pVax1/pet-neu) was designed to encode 12 different Her-2/ErbB-2-derived, HLA-A*0201-restricted dominant and high-affinity heteroclitic cryptic epitopes. Vaccination with pVax1/pet-neu triggered multiple and ErbB-2-specific CTL responses in HLA-A*0201 transgenic HHD mice and in HLA-A*0201 healthy donors in vitro. Human and murine CTL specific for each one of the 12 ErbB-2 peptides recognized in vitro both human and murine tumor cells overexpressing endogenous ErbB-2. Furthermore, vaccination of HHD mice with pVax1/pet-neu significantly delayed the in vivo growth of challenged ErbB-2-expressing tumor (EL4/HHD/neu murine thymoma) more actively when compared with vaccination with the empty vector (pVax1) or vehicle alone. These data indicate that the pVax1/pet-neu cDNA vaccine coding for a poly-ErbB-2 epitope is able to generate simultaneous ErbB-2-specific antitumor responses against dominant and cryptic multiple epitopes.

Induction of multiple CD8+ T cell responses against the inducible Hsp70 employing an Hsp70 oligoepitope peptide.

The inducible heat shock protein Hsp70 has been described as a tumour antigen being frequently overexpressed in tumours of various histologic origins, with a role in tumourigenicity, as a critical event in tumour progression. A strategy to enhance the immune response to an antigen is the identification of multiple epitopes and the induction of a polyspecific response. Applied to tumour vaccination, such a polyspecific response should lead to a more robust antitumour efficacy. The long peptide Hsp70380-402 encompasses three nonamer peptides with a high affinity for HLA-A *0201. In a previous paper, we have shown that two of these nonamer peptides, p391 and p393, can raise CTL to recognize tumour cells overexpressing Hsp70. In the present paper, we demonstrate that the third nonamer peptide, p380, is a new epitope efficient in raising an antitumour immune response. The p380-402 polypeptide was able to induce an immune response against each of the three constituent epitopes both in vivo in HLA-A *0201 transgenic mice and in vitro with human PBMC. This polypeptide therefore constitutes an interesting candidate for the induction of multiple HLA-A *0201-restricted anti-Hsp70 antitumour CTL responses.

High-affinity HLA-A(*)02.01 peptides from parathyroid hormone-related protein generate in vitro and in vivo antitumor CTL response without autoimmune side effects.

Parathyroid hormone-related protein (PTH-rP), a protein produced by prostate carcinoma and other epithelial cancers, is a key agent in the development of bone metastases. We investigated whether the protein follows the self-tolerance paradigm or can be used as a target Ag for anticancer immunotherapy by investigating the immunogenicity of two HLA-A(*)02.01-binding PTH-rP-derived peptides (PTR-2 and -4) with different affinity qualities. PTH-rP peptide-specific CTL lines were generated from the PBMC of two HLA-A(*)02.01(+) healthy individuals, stimulated in vitro with PTH-rP peptide-loaded autologous dendritic cells and IL-2. The peptide-specific CTLs were able to kill PTH-rP(+)HLA-A(*)02.01(+) breast and prostate carcinoma cell lines. The two peptides were also able to elicit a strong antitumor PTH-rP-specific CTL response in HLA-A(*)02.01 (HHD) transgenic mice. The vaccinated mice did not show any sign of side effects due to cell-mediated autoimmunity or toxicity. In this study we describe two immunogenic and toxic-free PTH-rP peptides as valid candidates for the design of peptide-based vaccination strategies against prostate cancer and bone metastases from the most common epithelial malignancies.

Generation of CTL recognizing an HLA-A*0201-restricted epitope shared by MAGE-A1, -A2, -A3, -A4, -A6, -A10, and -A12 tumor antigens: implication in a broad-spectrum tumor immunotherapy.

MAGE-A1, -A2, -A3, -A4, -A6, -A10, and -A12 are expressed in a significant proportion of primary and metastatic tumors of various histological types and are targets of tumor Ag-specific CTL. Individual MAGE-A expression varies from one tumor type to the other but, overall, the large majority of tumors expresses at least one MAGE-A Ag. Therefore, targeting epitopes shared by all MAGE-A Ags would be of interest in immunotherapy against a broad spectrum of cancers. In the present study, we describe a heteroclitic MAGE-A peptide (p248V9) that induces CTL in vivo in HLA-A*0201 transgenic HHD mice and in vitro in healthy donors. These CTL are able to recognize two low HLA-A*0201 affinity peptides differing at their C-terminal position and derived from MAGE-A2, -A3, -A4, -A6, -A10, and -A12 (p248G9) and MAGE-A1 (p248D9). Interestingly, p248V9-specific CTL respond to endogenous MAGE-A1, -A2, -A3, -A4, -A6, -A10, and -A12 in an HLA-A*0201-restricted manner and recognize human HLA-A*0201(+)MAGE-A(+) tumor cells of various histological origin. Therefore, this heteroclitic peptide may be considered as a potent candidate for a broad-spectrum tumor vaccination.

HER-2/neu and hTERT cryptic epitopes as novel targets for broad spectrum tumor immunotherapy.

Tolerance to tumor-nonmutated self proteins represents a major obstacle for successful cancer immunotherapy. Since this tolerance primarily concerns dominant epitopes, we hypothesized that targeting cryptic epitopes that have a low affinity for HLA could be an efficient strategy to breach the tolerance to tumor Ags. Using the P1Y heteroclitic peptide approach, we identified low affinity cryptic HLA-A*0201-restricted epitopes derived from two widely expressed tumor Ags, HER-2/neu and hTERT. The P1Y variants of four HER-2/neu (neu(391), neu(402), neu(466), neu(650))- and two hTERT (hTERT(572) and hTERT(988))-derived low affinity peptides exhibited strong affinity for HLA-A*0201 and stimulated specific CTL from healthy donor PBMCs. These CTL specifically recognized HER-2/neu- and hTERT-expressing tumor cells of various histological origins. In vivo studies showed that HLA-A*0201 transgenic HHD mice vaccinated with the P1Y variant peptides generated CTL that specifically lysed Ag-expressing tumor cells, thus recognizing the cognate endogenous Ags. These results suggest that heteroclitic variants of low affinity, cryptic epitopes of widely expressed tumor Ags may serve as valid tools for tumor immunotherapy.

ALK as a novel lymphoma-associated tumor antigen: identification of 2 HLA-A2.1-restricted CD8+ T-cell epitopes.

Oncogenic anaplastic lymphoma kinase (ALK) fusion proteins (NPM/ALK and associated variants) are expressed in about 60% of anaplastic large cell lymphomas (ALCLs) but are absent in normal tissues. In this study, we investigated whether ALK, which is expressed at high levels in lymphoma cells, could be a target for antigen-specific cell-mediated immunotherapy. A panel of ALK-derived peptides was tested for their binding affinity to HLA-A*0201 molecules. Binding peptides were assessed for their capacity to elicit a specific immune response mediated by cytotoxic T lymphocytes (CTLs) both in vivo, in HLA-A*0201 transgenic mice, and in vitro in the peripheral blood lymphocytes (PBLs) from healthy donors. Two HLA-A*0201-restricted CTL epitopes, p280-89 (SLAMLDLLHV) and p375-86 (GVLLWEIFSL), both located in the ALK kinase domain were identified. The p280-89- and p375-86-induced peptide-specific CTL lines were able to specifically release interferon-gamma (IFN-gamma) on stimulation with ALK peptide-pulsed autologous Epstein-Barr virus-transformed B cells (LCLs) or T2 cells. Anti-ALK CTLs lysed HLA-matched ALCL and neuroblastoma cell lines endogenously expressing ALK proteins. CTL activity was inhibited by anti-HLA-A2 monoclonal antibody CR11.351, consistent with a class I-restricted mechanism of cytotoxicity. These results show the existence of functional anti-ALK CTL precursors within the peripheral T-cell repertoire of healthy donors, clearly indicating ALK as a tumor antigen and ALK-derived peptides, p280-89 and p375-86, as suitable epitopes for the development of vaccination strategies.

Tumor-associated antigen human chorionic gonadotropin beta contains numerous antigenic determinants recognized by in vitro-induced CD8+ and CD4+ T lymphocytes.

The beta subunit of human chorionic gonadotropin (hCG beta) is markedly overexpressed by neoplastic cells of differing histological origin including those present in colon, breast, prostate and bladder tumors. We have previously shown that some patients with hCG beta-producing urothelial tumors have circulating T cells that proliferate in response to hCG beta. To make a comprehensive study of hCG beta as a potential target for cancer immunotherapy, we investigated whether hCG beta peptides could induce CD4+ or CD8+ T-cell responses in vitro. By stimulating peripheral blood mononuclear cells (PBMCs) from three donors with mixtures of overlapping 16-mer synthetic peptides analogous to portions of either the hCG beta 20-71 or the hCG beta 102-129 region, we established six CD4+ T-cell lines that proliferated specifically in response to five distinct determinants located within these two hCG beta regions. Three antigenic determinants (hCG beta 52-67, 106-121 and 114-125) were presented by HLA-DR molecules, while the two other antigenic determinants (hCG beta 48-63 and 56-67) were presented by HLA-DQ molecules. Interestingly, one T-cell line specific for peptide hCG beta 106-121 recognized hCG beta peptides comprising, at position 117, either an alanine or an aspartic acid residue, with the latter residue being present within the protein expressed by some tumor cells. In addition, three other hCG beta-derived peptides that exhibited HLA-A*0201 binding ability were able to stimulate CD8+ cytotoxic T cells from two HLA-A*0201 donors. These three immunogenic peptides corresponded to regions hCG beta 40-48, hCG beta 44-52 and hCG beta 75-84. Our results indicate that the tumor-associated antigen hCG beta possesses numerous antigenic determinants liable to stimulate CD4+ and CD8+ T lymphocytes, and might thus be an effective target antigen for the immunotherapy of hCG beta-producing tumors.