Redirecting mouse T hybridoma against human breast and ovarian carcinomas: in vivo activity against HER-2/neu expressing cancer cells

Immune System Effects on Breast Cancer

Breast cancer is one of the most common cancers in women, with the ability to metastasize to secondary organs, which is the main cause of cancer-related deaths. Understanding how breast tumors progress is essential for developing better treatment strategies against breast cancer. Until recently, it has been considered that breast cancer elicits a small immune response. However, it is now clear that breast tumor progression is either prevented by the action of antitumor immunity or exacerbated by proinflammatory cytokines released mainly by the immune cells. In this comprehensive review we first explain antitumor immunity, then continue with how the tumor suppresses and evades the immune response, and next, outline the role of inflammation in breast tumor initiation and progression. We finally review the current immunotherapeutic and immunoengineering strategies against breast cancer as a promising emerging approach for the discovery and design of immune system-based strategies for breast cancer treatment.

Gene-specific factors determine mitotic expression and bookmarking via alternate regulatory elements

Transcriptional silencing during mitosis is caused by inactivation of critical transcriptional regulators and/or chromatin condensation. Inheritance of gene expression patterns through cell division involves various bookmarking mechanisms. In this report, we have examined the mitotic and post-mitotic expression of the DRA major histocompatibility class II (MHCII) gene in different cell types. During mitosis the constitutively MHCII-expressing B lymphoblastoid cells showed sustained occupancy of the proximal promoter by the cognate enhanceosome and general transcription factors. In contrast, although mitotic epithelial cells were depleted of these proteins irrespectively of their MHCII transcriptional activity, a distal enhancer selectively recruited the PP2A phosphatase via NFY and maintained chromatin accessibility. Based on our data, we propose a novel chromatin anti-condensation role for this element in mitotic bookmarking and timing of post-mitotic transcriptional reactivation.

Re-targeting T-cells against cancer by gene-transfer of tumor-reactive receptors

BACKGROUND

Adoptive transfer of T-lymphocytes is a promising treatment for a variety of malignancies, but is often not feasible due to difficulties in generating T-cells reactive with the targeted antigen from patients. To facilitate rapid generation of cells for therapy, T-cells can be programmed with genes encoding for an antigen-specific T-cell receptor (TCR) or chimeric receptors.

OBJECTIVE

To discuss the molecular design and selected pitfalls of TCR gene modified T-cells and T-cells expressing chimeric receptors, so called T-bodies.

METHODS

A selected review of the recent literature.

CONCLUSION

Clinical trials report so far only limited efficacy of adoptively transferred genetically modified T-cells. However, the recent progress in engineering tumor-reactive T cells is providing a promising basis to further explore this treatment modality.

Cancer immunotherapy

Recent scientific advances have expanded our understanding of the immune system and its response to malignant cells. The clinical goal of tumour immunotherapy is to provide either passive or active immunity against malignancies by harnessing the immune system to target tumours. Monoclonal antibodies, cytokines, cellular immunotherapy, and vaccines have increasingly become successful therapeutic agents for the treatment of solid and haematological cancers in preclinical models, clinical trials, and practice. In this article, we review recent advances in the immunotherapy of cancer, focusing on new strategies and future perspectives as well as on clinical trials attempting to enhance the efficacy of immunotherapeutic modalities and translate this knowledge into effective cancer therapies.

Cytolytic and Cytotoxic Activity of a Human Natural Killer Cell Line Genetically Modified to Specifically Recognize HER-2/neu Overexpressing Tumor Cells

NK92 cells genetically engineered to recognize the HER-2/neu oncoprotein have been previously reported to lyse HER-2/neu positive tumor cell lines through direct cell to cell contact. In the present study we have transduced NK92 cells with a chimeric receptor gene composed of the HER-/neu specific scFv (FRP5) antibody fragment, joined to the peptide CD8 hinge region and the signaling CD3 zeta chain. NK92 cells expressing this chimeric receptor (NK92.HER-2/neu/zeta) specifically recognized and lysed HER-2/neu overexpressing tumor cell lines both in vitro and in preclinical tumor models in vivo. More important we demonstrate that NK92.HER-2/neu/zeta cells constitutively secrete high levels of soluble scFv which mediate strong tumor cytostatic effects by directly binding on cell surface HER-2/neu. Our data uncover an additional mechanism through which NK92.HER-2/neu/zeta cells mediate antitumor effects and further support their use in cell based therapeutics for the treatment of HER-2/neu expressing cancers.

Genetically engineered T cells expressing a HER2-specific chimeric receptor mediate antigen-specific tumor regression

In this report, we developed a chimeric receptor (N29gamma chR) involving the single chain Fv (scFv) derived from N29 monoclonal antibody (mAb) specific for p185HER2 and characterized the therapeutic efficacy of primary T cells engineered to express N29gamma chR in two histologically distinct murine tumor models. Murine breast (MT901) and fibrosarcoma (MCA207) cancer cell lines were engineered to express human HER2 as targets. Administration of N29gamma chR-expressing T cells eliminated 3-day pulmonary micrometastases of MT901/HER2 and MCA207/HER2 but not parental tumor cells. A 5 to 8-fold increased dose of N29gamma T cells was required to mediate regression of advanced 8-day macrometastases. Exogenous administration of interleukin-2 (IL-2) after N29gamma T-cell transfer was dispensable for treatment of 3-day micrometastases, but was required for mediating regression of well-established 8-day macrometastases. Moreover, fractionated CD8 T cells expressing N29gamma chR suppressed HER2-positive tumor cell growth after adoptive transfer independent of CD4(+) cells. These data indicate that genetically modified T cells expressing a HER2-targeting chimeric receptor can mediate antigen-specific regression of preestablished metastatic cancers in a cell dose-dependent fashion. Systemic administration of IL-2 augments the therapeutic efficacy of these genetically engineered T cells in advanced diseases. These results are relevant to the implication of genetically redirected T cells in clinical cancer immunotherapy.

Combining adoptive cellular and immunocytokine therapies to improve treatment of B-lineage malignancy

Currently, the lineage-specific cell-surface molecules CD19 and CD20 present on many B-cell malignancies are targets for both antibody- and cell-based therapies. Coupling these two treatment modalities is predicted to improve the antitumor effect, particularly for tumors resistant to single-agent biotherapies. This can be shown using an immunocytokine, composed of a CD20-specific monoclonal antibody fused to biologically active interleukin 2 (IL-2), combined with ex vivo expanded human umbilical cord blood-derived CD8(+) T cells, that have been genetically modified to be CD19 specific, for adoptive transfer after allogeneic hematopoietic stem-cell transplantation. We show that a benefit of targeted delivery of recombinant IL-2 by the immunocytokine to the CD19(+)CD20(+) tumor microenvironment is improved in vivo persistence of the CD19-specific T cells, and this results in an augmented cell-mediated antitumor effect. Phase I trials are under way using anti-CD20-IL-2 immunocytokine and CD19-specific T cells as monotherapies, and our results warrant clinical trials using combination of these two immunotherapies.

Targeting of tumor cells by lymphocytes engineered to express chimeric receptor genes

Adoptive cellular immunotherapy of cancer has been limited to date mostly due to the poor immunogenicity of tumor cells, the immunocompromised status of cancer patients in advanced stages of their disease, and difficulties in raising sufficient numbers of autologous tumor-specific T lymphocytes. On the other hand, the slow tumor penetration and short half-life of exogenously administered tumor-specific monoclonal antibodies have provided major obstacles for an effective destruction of tumor cells by the humoral effector arm of the immune system. Attempts to improve the efficacy of adoptive cellular cancer immunotherapy have led to the development of novel strategies that combine advantages of T cell-based (i.e., efficient tumor penetration, cytokine release and cytotoxicity) and antibody-based (high specificity for tumor-associated antigens) immunotherapy by grafting cytotoxic T lymphocytes (CTLs) with chimeric receptors composed of antibody fragments (which recognize tumor-cell antigens) and a cellular activation motif. Antigen recognition is therefore not restricted by major histocompatibility genes, as the physiological T-cell receptor, but rather is directed to native cell surface structures. Since the requirements of major histocompatibility complex (MHC) restriction in the interaction of effector cells with target cells are bypassed, the tumor cell-binding of CTLs grafted with chimeric receptors is not affected by down-regulation of HLA class I antigens and by defects in the antigen-processing machinery. Ligand binding by the chimeric receptor triggers phosphorylation of immunoglobulin tyrosine activation motifs (ITAMs) in the cytoplasmic region of the molecule and this activates a signaling cascade that is required for the induction of cytotoxicity, cytokine secretion and proliferation. Here, the authors discuss the potential of lymphocytes grafted with chimeric antigen receptors in the immunotherapy of malignant disease.

Gene transfer approaches in cancer immunotherapy

The idea of enhancing or establishing effective immune response against endogenously developed tumor cells is not novel. More than a hundred years ago, bacterial components were used to develop antitumor immune response. Later, when a number of immune system-effecting cytokines had been discovered, they were used for systemic treatment of cancer patients. However, systemic treatment often resulted in even negative outcome. Recent developments of genetic approaches of cell modifications allowed developing of modern techniques of targeted tumor cell elimination. In the present paper, we review modern trends of the antitumor response enhancement based on immunoregulatory gene transfer into different cell types both in vivo and in vitro. Almost all these approaches are based on the activation of the adaptive arm of the immune system in response to tumor cells. However, recent studies indicate that the innate arm of the immune system, as well as adaptive arm, is involved in tumor suppression. The innate immune system uses nonrearranging germline receptors, which could trigger cellular effector responses that are conditional (or instructive) to the subsequent adaptive immune response. Last years' viewpoints on 'self' and 'non-self' recognition and primary induction of the immune response have changed. The key role of lymphocytes is pathogen recognition and, following immune response induction, switched on the central role of dendritic cells in 'non-self' recognition and induction of both innate and adaptive responses. Moreover, innate response is supposed to be an essential starting point in induction of successful and effective acquired response. Most cancer vaccines do not have 'non-self' marks presentation due to their endogenous origin, thus lacking their effectiveness in the induction of the specific long-lasting immune response. Taking this point into consideration, we can conclude that to make cancer vaccine more effective we have to present tumor antigens, together with the molecules that can potentially activate downstream 'non-self' recognition events not in parallel, but as a consequence of tumor antigen processing and presentation.

Immunobiology of HER-2/neu oncoprotein and its potential application in cancer immunotherapy

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.