Depletion of regulatory T cells by targeting folate receptor 4 enhances the potency of a GM-CSF-secreting tumor cell immunotherapy.

In this report, a Treg-depleting anti-FR4 antibody is combined with a GM-CSF-secreting tumor cell immunotherapy (GVAX) for treatment of melanoma-bearing animals. Median survival time (MST) of animals treated with GVAX was 41 days, compared to a MST of 32 days in untreated animals. Anti-FR4 monotherapy had no effect on MST.

Allogeneic GM-CSF-secreting tumor cell immunotherapies generate potent anti-tumor responses comparable to autologous tumor cell immunotherapies.

Clinical studies of cell-based immunotherapies have included both patient-specific (autologous) and non-patient-specific (allogeneic) approaches. Major concerns in using allogeneic immunotherapies are that the induced immune responses may be predominantly directed against the allogeneic HLA molecules of the cellular immunotherapy and not against its potential tumor antigens and that only the allogeneic responses will be enhanced when the immunotherapies are combined with immune checkpoint regulators in an effort to enhance overall immunotherapy potency. To evaluate these possibilities, studies were performed using the GM-CSF-secreting B16F1 cell line as autologous immunotherapy (Auto) and the same cell line modified to over-express the MHC molecule K(d) to generate an immunotherapy that expresses an allogeneic component (Allo) when injected into C57/Bl6 mice.

Evaluation of biodistribution of a fiber-chimeric, conditionally replication-competent (oncolytic) adenovirus in CD46 receptor transgenic mice.

The limited efficacy of adenovirus type 5 (Ad5)-based oncolytic viruses seen in the clinic thus far may be attributable in part to variable expression of its receptor on tumor cells. Replacement of the Ad5 fiber knob with the Ad35 fiber knob generated the Ad5/35 chimeric virus, which has previously been demonstrated to have significant antitumor activity in murine tumor models, presumably by virtue of its recognition of the CD46 receptor, which is abundant on many types of tumor cells. In the current study, a CD46 receptor transgenic mouse strain (hCD46Ge) that expresses the CD46 receptor in a pattern closely mirroring that in humans was used to study the in vivo properties of Ad5/Ad35 chimeric viruses.

Anti-programmed death-1 synergizes with granulocyte macrophage colony-stimulating factor--secreting tumor cell immunotherapy providing therapeutic benefit to mice with established tumors.

Purpose: The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy, which is known to stimulate potent and long-lasting antigen-specific immune responses, in combination with PD-1 blockade, which has been shown to augment cellular immune responses.

Experimental Design: Survival studies were done in the B16 melanoma and CT26 colon carcinoma tumor models. Immune monitoring studies were done in the B16 model.

Novel immunocompetent murine tumor model for evaluation of conditionally replication-competent (oncolytic) murine adenoviral vectors.

Oncolytic adenoviral vectors that express immunostimulatory transgenes are currently being evaluated in clinic. Preclinical testing of these vectors has thus far been limited to immunodeficient xenograft tumor models since human adenoviruses do not replicate effectively in murine tumor cells. The effect of the immunostimulatory transgene on overall virus potency can therefore not be readily assessed in these models.

Intratumoral coadministration of hyaluronidase enzyme and oncolytic adenoviruses enhances virus potency in metastatic tumor models.

Purpose: Evaluate the codelivery of hyaluronidase enzyme with oncolytic adenoviruses to determine whether it improves the spread of the virus throughout tumors, thereby leading to a greater overall antitumor efficacy in tumor models.

Experimental Design: The optimal dose of hyaluronidase that provided best transduction efficiency and spread of a green fluorescent protein (GFP)-expressing adenovirus within tumors was combined with oncolytic viruses in tumor models to determine whether the combination treatment results in an improvement of antitumor efficacy.

Results: In mice injected with the adenovirus Ad5/35GFP and an optimal dose of hyaluronidase (50 U), a significant increase in the number of GFP-expressing cells was observed when compared with animals injected with virus only (P < 0.

Lymphocyte activation gene-3 fusion protein increases the potency of a granulocyte macrophage colony-stimulating factor-secreting tumor cell immunotherapy.

Purpose: The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy, which is known to stimulate a potent and long-lasting antigen-specific immune response in combination with lymphocyte activation gene-3 fusion protein (LAG-3Ig), which has been shown to act as an adjuvant for priming T helper type 1 and cytotoxic T-cell responses.

Experimental Design: Survival and immune monitoring studies were done in the B16 melanoma model. GM-CSF-secreting tumor cell immunotherapy was administered as a single s.

Enhancement of the anti-tumor efficacy of a GM-CSF-secreting tumor cell immunotherapy in preclinical models by cytosine arabinoside.

Objective: Acute myeloid leukemia (AML) is a highly malignant neoplasm responsible for nearly 10,000 cancer-related deaths annually in the United States. Treatment options for elderly patients with AML remain limited. Standard regimens using cytarabine (cytosine arabinoside [AraC]), a nucleotide analogue, result in significant toxicity with poor overall response.

Local secretion of anti-CTLA-4 enhances the therapeutic efficacy of a cancer immunotherapy with reduced evidence of systemic autoimmunity.

Promising anti-tumor responses have been observed in the clinic using monoclonal antibodies (mAbs) that block immune checkpoints. One concern with these therapeutic agents remains the potential induction of immune breakthrough events (IBEs) resulting from the disruption of T cell homeostasis or the breaking of tolerance to self antigens. As an approach to maintaining anti-tumor responses but decreasing the likelihood of these events, the local expression of a mAb in combination with a GM-CSF-secreting cancer immunotherapy was evaluated.

GM-CSF-secreting cancer immunotherapies: preclinical analysis of the mechanism of action.

Granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapies have demonstrated long-lasting, and specific anti-tumor immune responses in animal models. The studies reported here specifically evaluate two aspects of the immune response generated by such immunotherapies: the persistence of irradiated tumor cells at the immunization site, and the breadth of the immune response elicited to tumor associated antigens (TAA) derived from the immunotherapy. To further define the mechanism of GM-CSF-secreting cancer immunotherapies, immunohistochemistry studies were performed using the B16F10 melanoma tumor model.

An antibody delivery system for regulated expression of therapeutic levels of monoclonal antibodies in vivo.

Monoclonal antibody (mAb) delivery by gene transfer in vivo may be an attractive alternative to current mAb therapies for applications that require long-term therapy. This article describes a transfer system that allows inducible high-level expression of unmodified mAbs in vivo. A recombinant adeno-associated viral (rAAV) vector is used that comprises an expression cassette consisting of a dimerizer-regulated promoter that drives expression of the antibody heavy and light chains linked by a 2A self-processing peptide and a furin cleavage site.

Recombinant IL-7 enhances the potency of GM-CSF-secreting tumor cell immunotherapy.

IL-7 is known for its role in lymphopoiesis and T-cell homeostasis. In addition, its capacity to augment the immune response to weak or low affinity antigens makes it an ideal candidate to evaluate in combination with a GM-CSF-secreting tumor cell immunotherapy, which has been shown to elicit broad humoral and cellular immune responses. The studies reported here show that IL-7, when combined with a GM-CSF-secreting tumor cell immunotherapy, significantly prolonged the survival of tumor-bearing mice.

Vascular endothelial growth factor blockade reduces intratumoral regulatory T cells and enhances the efficacy of a GM-CSF-secreting cancer immunotherapy.

Purpose: The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)-secreting tumor cell immunotherapy in combination with vascular endothelial growth factor (VEGF) blockage in preclinical models.

Experimental Design: Survival and immune response were monitored in the B16 melanoma and the CT26 colon carcinoma models. VEGF blockade was achieved by using a recombinant adeno-associated virus vector expressing a soluble VEGF receptor consisting of selected domains of the VEGF receptors 1 and 2 (termed sVEGFR1/R2).

AAV serotype 8-mediated gene delivery of a soluble VEGF receptor to the CNS for the treatment of glioblastoma.

The presence of the blood-brain barrier complicates drug delivery in the development of therapeutic agents for the treatment of glioblastoma multiforme (GBM). The use of local gene transfer in the brain has the potential to overcome this delivery barrier by allowing the expression of therapeutic agents directly at the tumor site. In this study, we describe the development of a recombinant adeno-associated (rAAV) serotype 8 vector that encodes an optimized soluble inhibitor, termed sVEGFR1/R2, of vascular endothelial growth factor (VEGF).

Dual promoter-controlled oncolytic adenovirus CG5757 has strong tumor selectivity and significant antitumor efficacy in preclinical models.

Purpose: Transcriptionally controlled oncolytic adenovirus CG5757 is engineered with two tumor-specific promoters from E2F-1 and human telomerase reverse transcriptase genes. This virus has broad anticancer spectrum and higher specificity. The objective of the current study is to show its antitumor selectivity and therapeutic potential.

Inhibition of lymphogenous metastasis using adeno-associated virus-mediated gene transfer of a soluble VEGFR-3 decoy receptor.

The presence of metastases in regional lymph nodes is a strong indicator of poor patient survival in many types of cancer. It has recently been shown that the lymphangiogenic growth factor, vascular endothelial growth factor-C (VEGF-C), and its receptor, VEGF receptor-3 (VEGFR3), may play a pivotal role in the promotion of metastasis to regional lymph nodes. In this study, human prostate and melanoma tumor models that preferentially metastasize to the lymph nodes following s.

Stable antibody expression at therapeutic levels using the 2A peptide.

Therapeutic monoclonal antibodies (mAbs) are currently being developed for the treatment of cancer and other diseases. Despite clinical success, widespread application of mAb therapies may be limited by manufacturing capabilities. In this paper, we describe a mAb delivery system that allows continuous production of a full-length antibody at high-concentrations in vivo after gene transfer.

Administration of IFN-alpha enhances the efficacy of a granulocyte macrophage colony stimulating factor-secreting tumor cell vaccine.

IFN-alpha is approved for the treatment of multiple cancers. Its pleiotropic properties include inhibition of proliferation and angiogenesis and induction of apoptosis. Type I IFNs also exert immunomodulatory effects, which make it an appropriate candidate to combine with cancer vaccines.

Identification of pretreatment agents to enhance adenovirus infection of bladder epithelium.

Adenovirus has been used widely as a gene transfer vector in the laboratory and clinic for the purpose of gene therapy. Conditionally replication-competent oncolytic adenoviruses are capable of multiplying up to a thousand old in target cells, a property that might prove to be of tremendous potential in the area of cancer therapy. Intravesicular therapy of refractory superficial bladder cancer employing an oncolytic adenovirus would allow for local administration and efficient delivery of virus to bladder tumor.

Anti-tumor efficacy of human angiostatin using liver-mediated adeno-associated virus gene therapy.

Angiostatin is a potent endogenous inhibitor of angiogenesis and tumor growth in vivo. The therapeutic potential of adeno-associated viral (AAV) gene delivery of angiostatin in modulating tumor growth in vivo was evaluated. Sustained levels of angiostatin were detected in the sera of mice for up to 6 months after they received a single injection of AAV-angiostatin.

Production of human clotting Factor IX without toxicity in mice after vascular delivery of a lentiviral vector.

Replication-deficient lentiviral vectors (LV) have been shown to enable the stable genetic modification of multiple cell types in vivo. We demonstrate here that vascular and hepatic delivery of a third-generation HIV-derived lentiviral vector encoding human Factor IX (LV-hFIX) produced potentially therapeutic serum levels of hFIX protein with no vector-mediated local or systemic toxicity of adult mice. Portal vein administration produced the highest serum levels of hFIX and demonstrated proportionally higher levels of gene transfer to the liver with up to 4% of hepatocytes expressing hFIX.