Eradication Of Established Tumors Research Articles

Illuminating Tumors with LIGHT

One reason that tumors continue to grow unabated is that the immune system fails to mount a response to them. Solid tumors consist not only of the cancerous cells, but also a cast of supporting tissue in the form of stroma, which includes fibroblasts and vasculature. The tumor necrosis superfamily member LIGHT binds to the lymphotoxin-β receptor (LTβR) stromal cells and stimulates chemokine and adhesion molecule expression. LIGHT also binds T cells and serves as a costimulatory signal for T cell priming. Yu et al. found that expression of LIGHT, which was engineered to be resistant to proteolysis to increase surface expression, on tumor cells (Ag104 fibrosarcoma expressing the T cell epitope H-2L d ) promoted their rejection upon injection into host mice. The mice exposed to the LIGHT-expressing tumor then also rejected subsequent Ag104L d tumors, even those not expressing LIGHT. Mice with established Ag104L d tumors also showed tumor regression if Ag104L d -LIGHT cells were injected into the tumor or were injected at a distal nontumorous site. Depletion of CD8 + T cells or exposure of the tumor-injected mice to an LTβR-immunoglobulin fusion protein, which competes for stromal LTβR binding of LIGHT, allowed tumor growth to proceed. Analysis of the Ag104L d -LIGHT tumors from the mice, prior to rejection, showed that the stroma was stimulated to produce several chemokines and the adhesion molecule MAdCAM-1. Furthermore, naïve T cells were recruited to the tumor and activated. Thus, expression of LIGHT on a tumor population may allow the immune system to mount a response promoting the body's natural mechanism for defense against abnormal cells (see Houghton for commentary). P. Yu, Y. Lee, R. K. Chin, J. Wang, Y. Wang, A. Schietinger, M. Philip, H. Schreiber, Y.-X. Fu, Priming of naïve T cells inside tumors leads to eradication of established tumors. Nat. Immunol. 5 , 141-149 (2004). [Online Journal] A. L. Houghton, LIGHTing the way for tumor immunity. Nat. Immunol. 5 , 123-124 (2004). [Online Journal]

Complete tumour regressions induced by vaccination with IL-12 gene-transduced tumour cells in combination with IL-15 in a melanoma model in mice.

In the present study, IL-12 gene-transduced B78-H1 melanoma cells (B78/IL-12) were used in combination with IL-15 to treat melanoma-bearing mice. Genetically modified B78/IL-12 cells, when injected subcutaneously, induced strong activation of antitumour mechanisms resulting in complete loss of tumourigenicity. In a therapeutic model, intratumoural injection of irradiated B78/IL-12 cells significantly delayed tumour growth and led to the regression of melanoma in one case. Similarly, consecutive daily injections of IL-15 markedly inhibited tumour progression with occasional curative effects. When used in combination, vaccination with B78/IL-12 cells and treatment with IL-15 caused eradication of established tumours in all treated mice. The combined treatment with B78/IL-12 cells and IL-15 activated not only a local response against tumour, but also induced systemic antitumour immunity that led to a delay or inhibition of tumour development at a distant site. In vitro studies demonstrated that when used together, B78/IL-12 cells and IL-15 induced a shift from a type Th2 to a type Th1 response. Activation of the antitumour immune response in double-treated mice resulted, in part, from stimulation of IFN-gamma production and was accompanied by the development of cytotoxic effectors in the spleen. As shown in a macrophage tumouricidal assay, macrophages could also play a role in the antitumour effects. The results confirmed that vaccination with IL-12 gene-modified tumour cells is superior to the treatment with unmodified tumour cell vaccine and, additionally, showed that IL-15 is an excellent candidate for adjuvant therapy, inducing synergistically not only a delay of tumour growth but also its complete eradication.

SMAC agonists blaze the TRAIL to tumor cells

Of prime concern in cancer therapy is the resistance of many tumors to current treatment regimes, often because of defects in the ability of tumor cells to undergo apoptosis. The aim of cancer biologists is therefore to develop new strategies that exclusively target tumor cells that are resistant to apoptosis. Apoptosis resulting in activation of caspases can be initiated by at least two stimulatory pathways: one requires activation of death receptors by death-inducing ligand members of the tumor necrosis factor (TNF) family and the other, initiated by chemotherapeutic agents, involves the release of pro-apoptotic factors such as cytochrome c and SMAC (second mitochondria-derived activator of caspases) from mitochondria. The cytotoxic ligand TRAIL (TNF-related apoptosis-inducing ligand) is a promising candidate for cancer therapy because it is selectively toxic to tumor cells with little or no toxicity evident in normal cells. The apoptotic signal initiated by TRAIL often results in mitochondrial perturbation and in many cells TRAIL engages a mitochondrial amplification loop for maximal cytotoxicity.

Specific immunotherapy against occult cancer metastases.

We investigated the efficacy of a preparation containing High Five (H5) insect cells infected with recombinant baculovirus encoding the murine interferon-beta gene (H5BVIFN-beta) against established primary tumors and occult lung metastases. Injection of live or lyophilized H5BVIFN-beta into established subcutaneous tumors of the highly metastatic murine UV-2237m fibrosarcoma or K-1735M2 melanoma in syngeneic mice eradicated both primary tumors and preexisting lung metastases. The therapeutic effects of H5BVIFN-beta were not observed in nude mice and were diminished in syngeneic mice depleted of CD4(+) and CD8(+) T cells. Immunohistochemical staining showed that tumors injected with H5BVIFN-beta were densely infiltrated by CD4(+) and CD8(+) T cells in mice with normal CD4/CD8 complement. These data demonstrate that, unlike most immunologic approaches in which prophylaxis can be achieved but eradication of established tumor is rare, lyophilized preparations of H5BVIFN-beta can serve as a novel immunotherapy against both primary tumors and their occult metastases.

E1B-55K-deleted adenovirus expressing E1A-13S by AFP-enhancer/promoter is capable of highly specific replication in AFP-producing hepatocellular carcinoma and eradication of established tumor.

Here, we constructed a recombinant replication-competent adenovirus (rRCAd; AdAFPep/Rep) that expresses both E1A-13S driven by the alpha-fetoprotein (AFP) enhancer/promoter (AFPep) lacking any silencers in the 5'-flanking region of the AFP gene, and 55K-deleted E1B driven by the cytomegalovirus (CMV) promoter. We then examined the feasibility of gene therapy utilizing this virus for AFP-producing hepatocellular carcinoma (HCC). AdAFPep/Rep lysed all the AFP-producing HCC cell lines (HuH7, HepG2, PLC/PRF/5 (P5)) examined at a multiplicity of infection (MOI) as low as 0.1 and did not lyse primary human hepatocytes (Hc) at a MOI as high as 100, indicating that the rRCAd virus can lyse AFP-producing HCC cells with a higher specificity and potency than previously reported. Furthermore, this virus was capable of complete eradication of a preestablished HuH7-cell tumor by a single intratumoral injection of 10(8) plaque-forming units (pfu) of AdAFPep/Rep. Thus, AdAFPep/Rep may be applicable for clinical use.

Adenovirus-mediated delivery of antiangiogenic genes as an antitumor approach.

Based on the observation that the growth of solid tumors is dependent on the formation of new blood vessels, therapeutic strategies aimed at inhibiting angiogenesis have been proposed. A number of proteins with angiostatic activity have been described, but their development as therapeutic agents has been hampered by difficulties in their production and their poor pharmacokinetics. These limitations may be resolved using a gene therapy approach whereby the genes are delivered and expressed in vivo. Here we compared adenoviral delivery of endostatin, proliferin-related protein (PRP), and interferon-inducible protein 10 (IP10) genes. Recombinant adenoviruses carrying the three angiostatic genes express biologically active gene products as determined in vitro in endothelial cell proliferation and migration assays, and in vivo by inhibition of neoangiogenesis in rat chambers. Eradication of established tumors in vivo, in the murine B16F10 melanoma model in immunocompetent mice, was not achieved by intratumoral injection of the different vectors. However, the combination of intravenous plus intratumoral injections allowed rejection of tumors. Ad-PRP or Ad-IP10 were significantly more efficient than Ad-endostatin, leading to complete tumor rejection and prolonged survival in a high proportion of treated animals. These data support the use of in vivo gene delivery approaches to produce high-circulating and local levels of antiangiogenic agents for the therapy of local and metastatic human tumors.

Cyclophosphamide enhances anti-tumor effect of wild-type p53-specific CTL.

The tumor suppressor protein p53 is overexpressed in up to 50% of all human malignancies, both in solid tumors as well as hematological malignancies, and is therefore an attractive target for immunotherapy. We have recently shown that cytotoxic T lymphocytes (CTL), raised in p53 gene deficient (p53 -/-) mice and recognizing a murine wild-type (wt) p53 peptide, were able to eradicate a mutant p53-induced and overexpressing tumor in p53 +/+ nude mice. These CTL also prevented the outgrowth of a more aggressive p53-overexpressing tumor in immunocompetent C57BL/6 mice. Importantly, this occurred in the absence of demonstrable damage to normal tissue. Possibly due to the aggressive nature of the latter tumor, adoptive transfer of wtp53-specific CTL did not result in the eradication of established tumors, either in nude or immunocompetent mice. Therefore, we explored whether the cytotoxic drug cyclophosphamide (CY) could potentiate the therapeutic activity of wtp53-specific CTL. We show here that CY acts synergistically with adoptively transferred wtp53-specific CTL in controlling the growth of an aggressive mutant p53-induced and overexpressing tumor. Previously described mechanisms underlying the synergism between CY and immune T cells were evaluated, but were not found to be operational in this model.

Distinct role of antigen-specific T helper type 1 (Th1) and Th2 cells in tumor eradication in vivo.

The role of T helper type 1 (Th1) and Th2 cells in tumor immunity was investigated using Th cells induced from ovalbumin (OVA)-specific T cell receptor transgenic mice. Although Th1 cells exhibited stronger cytotoxicity than Th2 cells, both cell types completely eradicated tumors when transferred into mice bearing A20 tumor cells transfected with the OVA gene (A20-OVA). Th1 cells eradicated the tumor mass by inducing cellular immunity, whereas Th2 cells destroyed the tumor by inducing tumor necrosis. Both Th1 and Th2 cells required CD8(+) T cells to eliminate tumors, and neither of these cells were able to completely eliminate A20-OVA tumors from T and B cell-deficient RAG2(-/-) mice. Mice cured from tumors by Th1 and Th2 cell therapy rejected A20-OVA upon rechallenge, but CD8(+) cytotoxic T lymphocytes were induced only from spleen cells prepared from cured mice by Th1 cell therapy. Moreover, we demonstrated that Th1 and Th2 cells used distinct adhesion mechanisms during tumor eradication: the leukocyte function-associated antigen (LFA)-1-dependent cell-cell adhesion step was essential for Th1 cell therapy, but not for Th2 cell therapy. These findings demonstrated for the first time the distinct role of antigen-specific Th1 and Th2 cells during eradication of established tumors in vivo.

The Multi-epitope Approach for Immunotherapy for Cancer: Identification of Several CTL Epitopes from Various Tumor-Associated Antigens Expressed on Solid Epithelial Tumors

ABSTRACT: One approach to development of specific cancer immunotherapy relies on the induction of cytotoxic T lymphocytes (CTL) specific for tumor-associated antigens (TAA). Induction of TAA-specific CTL could be used towards the eradication of established tumors, or to prevent their dissemination or recurrence after primary treatment. The present study identifies a set of CTL epitopes from TAA frequently found on solid epithelial tumors such as breast, lung and gastro-intestinal tumors. Specifically, HLA-A2.1 binding peptides from the MAGE2, MAGE3, HER-2/ neu and CEA antigens were tested for their capacity to elicit in vitro anti-tumor CTL using lymphocytes from normal volunteers and autologous dendritic cells as antigen-presenting cells. A total of 6 new epitopes (MAGE2[10 157], MAGE3[9 112], CEA[9 691], CEA[9 24], HER2[9 435] and HER2[9 5]) were identified which were capable of specifically recognizing tumor cell lines expressing HLA-A2.1 and the corresponding TAA. In one case (CEA[9 24]), induction of vigorous anti-tumor CTL responses required epitope engineering to increase HLA-A2.1 binding affinity. Finally, most of the newly identified epitopes (5 out of 6) were found to be highly crossreactive with other common HLA alleles of the A2 supertype (A2.2, A2.3, A2.6 and A6802), thus demonstrating their potential in providing broad and non-ethnically biased population coverage. The results are discussed in the context of the development of multi-epitope-based therapies with broad applicability for patients suffering from commonly found tumors.

Eradication of established tumor by local injections of interferon gamma and lymphocytes from tumor bearing mice: Role of host immune reactivity

Eradication of established tumor by local injections of interferon gamma and lymphocytes from tumor bearing mice: Role of host immune reactivity