Embryonic Lethality in Homozygous Human Her-2 Transgenic Mice Due to Disruption of the Pds5b Gene.

The development of antigen-targeted therapeutics is dependent on the preferential expression of tumor-associated antigens (TAA) at targetable levels on the tumor. Tumor-associated antigens can be generated de novo or can arise from altered expression of normal basal proteins, such as the up-regulation of human epidermal growth factor receptor 2 (Her2/ErbB2). To properly assess the development of Her2 therapeutics in an immune tolerant model, we previously generated a transgenic mouse model in which expression of the human Her2 protein was present in both the brain and mammary tissue.

Three agonist antibodies in combination with high-dose IL-2 eradicate orthotopic kidney cancer in mice.

Background: Combination immunotherapies can be effective against subcutaneous tumors in mice but the effect against orthotopic malignant disease is less well characterized. In particular, a combination of three agonist antibodies, termed Tri-mAb, consisting of anti-DR5, anti-CD40 and anti-CD137 has previously been demonstrated to eradicate a large proportion of subcutaneous renal cell carcinoma (Renca) tumors (75% long-term survival), but the effect against orthotopic disease is not known.

Purpose: To determine the relative response of orthotopic tumors, we inoculated Renca into the kidney followed by treatment with Tri-mAb.

Multiple antitumor mechanisms downstream of prophylactic regulatory T-cell depletion.

Several reports have shown that prophylactic depletion of regulatory T cells (Treg) using various monoclonal antibodies (mAb) in mice can stimulate potent antitumor immune responses and prevent tumor development. These same depletion methods do not significantly suppress tumor growth in a therapeutic setting. Although different strategies to deplete FoxP3(+) Treg have been used, no study has systematically compared these qualitatively for the effector mechanisms they each liberate.

Anti-CD73 antibody therapy inhibits breast tumor growth and metastasis.

Extracellular adenosine is a potent immunosuppressor that accumulates during tumor growth. We performed proof-of-concept studies investigating the therapeutic potential and mechanism of action of monoclonal antibody (mAb)-based therapy against CD73, an ecto-enzyme overexpressed on breast-cancer cells that catalyzes the dephosphorylation of adenosine monophosphates into adenosine. We showed that anti-CD73 mAb therapy significantly delayed primary 4T1.

Toll-Like Receptor Triggering and T-Cell Costimulation Induce Potent Antitumor Immunity in Mice.

PURPOSE: To determine the antitumor activity of a novel combination of two immunomodulatory agents that simultaneously direct multiple components of immunity against cancer. EXPERIMENTAL DESIGN: We combined the Toll-like receptor agonist CpG 1826 with a T-cell costimulatory antibody specific for CD137 in an optimal treatment route and dosing schedule against established tumors in two mouse models. Mechanistic insight was gained using gene-deficient mice and cell-depleting antibodies.

CD1d-based combination therapy eradicates established tumors in mice.

The use of Abs that induce tumor cell death together with immunostimulatory reagents to activate innate and adaptive immune cells has emerged as a potent approach for the treatment of cancer. We have previously demonstrated that the use of three mAbs (anti-DR5, anti-CD40, anti-CD137) termed TriMab can induce rejection in a majority of mice with established experimental or carcinogen-induced tumors. However, given the potential toxicity of CD40 agonists in the clinic, we tested an alternative approach to directly activate/mature APCs using anti-CD1d mAbs.

CD1d activation and blockade: a new antitumor strategy.

CD1d is expressed on APCs and presents glycolipids to CD1d-restricted NKT cells. For the first time, we demonstrate the ability of anti-CD1d mAbs to inhibit the growth of different CD1d-negative experimental carcinomas in mice. Anti-CD1d mAbs systemically activated CD1d(+) APC, as measured by production of IFN-gamma and IL-12.

Type I natural killer T cells suppress tumors caused by p53 loss in mice.

CD1d-restricted T cells are considered to play a host protective effect in tumor immunity, yet the evidence for a role of natural killer T (NKT) cells in tumor immune surveillance has been weak and data from several tumor models has suggested that some (type II) CD1d-restricted T cells may also suppress some types of antitumor immune response. To substantiate an important role for CD1d-restricted T cells in host response to cancer, we have evaluated tumor development in p53(+/-) mice lacking either type I NKT cells (TCR Jalpha18(-/-)) or all CD1d-restricted T cells (CD1d(-/-)). Our findings support a key role for type I NKT cells in suppressing the onset of sarcomas and hematopoietic cancers caused by p53 loss but do not suggest that other CD1d-restricted T cells are critical in regulating the same tumor development.

Antibodies targeted to TRAIL receptor-2 and ErbB-2 synergize in vivo and induce an antitumor immune response.

Despite the development of human epidermal growth factor receptor-2 (ErbB-2/HER2)-targeted therapies, there remains an unmet medical need for breast cancer patients with ErbB-2 overexpression. We investigated the therapeutic activity of an agonist mAb to mouse tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor-2 (DR5) against ErbB2-driven breast cancer. Established tumors in BALB/c transgenic mice expressing a constitutively active ErbB-2/neuT were treated with anti-DR5 mAb and/or anti-ErbB-2 mAb and monitored for tumor progression.

Combination therapy of established cancer using a histone deacetylase inhibitor and a TRAIL receptor agonist.

Histone deacetylase inhibitors (HDACi) and agents such as recombinant tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and agonistic anti-TRAIL receptor (TRAIL-R) antibodies are anticancer agents that have shown promise in preclinical settings and in early phase clinical trials as monotherapies. Although HDACi and activators of the TRAIL pathway have different molecular targets and mechanisms of action, they share the ability to induce tumor cell-selective apoptosis. The ability of HDACi to induce expression of TRAIL-R death receptors 4 and 5 (DR4/DR5), and induce tumor cell death via the intrinsic apoptotic pathway provides a molecular rationale to combine these agents with activators of the TRAIL pathway that activate the alternative (death receptor) apoptotic pathway.

The effect of azacitidine on interleukin-6 signaling and nuclear factor-kappaB activation and its in vitro and in vivo activity against multiple myeloma.

Background: Azacitidine is a DNA methyltransferase inhibitor and cytotoxic agent known to induce apoptosis of some cancer cells. This study evaluated the pre-clinical potential of azacitidine as a therapeutic agent for multiple myeloma.

Design And Methods: Dose responsiveness to azacitidine was determined utilizing a panel of genetically heterogenous human multiple myeloma cell lines.

Interleukin 21 enhances antibody-mediated tumor rejection.

Interleukin-21 (IL-21) is a cytokine with structural and sequence homology to IL-2 and IL-15 that has antitumor activity alone in mouse experimental tumor models and a tolerable safety profile in phase I trials in patients with metastatic melanoma and renal cell carcinoma. Several monoclonal antibodies (mAb) targeted at tumor-associated antigens also have improved antitumor activities in mice when used in combination with IL-21. Recently, we described a rational three antibody-based approach (triple mAb, TrimAb) to eradicating established mouse tumors that required the generation of tumor-reactive CD8(+) T cells and IFN-gamma.

Demonstration of inflammation-induced cancer and cancer immunoediting during primary tumorigenesis.

Here we report the effects of loss of the Toll-like receptor-associated signaling adaptor myeloid-differentiation factor 88 (MyD88) on tumor induction in two distinct mouse models of carcinogenesis. The 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol 13-acetate (TPA)-induced skin papilloma model depends on proinflammatory processes, whereas the 3'-methylcholanthrene (MCA) induction of fibrosarcoma has been used by tumor immunologists to illustrate innate and adaptive immune surveillance of cancer. When exposed to a combination of DMBA/TPA, mice lacking MyD88 formed fewer skin papillomas than genetically matched WT controls treated in a similar manner.

Combined natural killer T-cell based immunotherapy eradicates established tumors in mice.

A rational monoclonal antibody (mAb)-based antitumor therapy approach has previously been shown to eradicate various established experimental and carcinogen-induced tumors in a majority of mice. This therapy comprised an agonistic mAb reactive with tumor necrosis factor-related apoptosis-inducing ligand receptor (DR5), expressed by tumor cells, an agonistic anti-CD40 mAb to mature dendritic cells, and an agonistic anti-4-1BB mAb to costimulate CD8(+) T cells. Because agonists of CD40 have been toxic in patients, we were interested in substituting anti-CD40 mAb with other dendritic cell-maturing agents, such as glycolipid ligands recognized by invariant natural killer T (iNKT) cells.

PKC412 demonstrates JNK-dependent activity against human multiple myeloma cells.

The effect and mode of action of the protein kinase C (PKC) inhibitor PKC412 on human multiple myeloma (MM) cell lines (HMCLs) and primary MM cells was explored. We found that PKC412 induced apoptosis of HMCLs and primary MM cells with variable efficacy; however, some activity was seen against all HMCLs and primary MM cells with at least 0.5 microM PKC412.