Induction and characterization of anti-tumor endothelium immunity elicited by ValloVax therapeutic cancer vaccine

Therapeutic approaches targeting CD95L/CD95 signaling in cancer and autoimmune diseases

Cell death plays a pivotal role in the maintenance of tissue homeostasis. Key players in the controlled induction of cell death are the Death Receptors (DR). CD95 is a prototypic DR activated by its cognate ligand CD95L triggering programmed cell death. As a consequence, alterations in the CD95/CD95L pathway have been involved in several disease conditions ranging from autoimmune diseases to inflammation and cancer. CD95L-induced cell death has multiple roles in the immune response since it constitutes one of the mechanisms by which cytotoxic lymphocytes kill their targets, but it is also involved in the process of turning off the immune response. Furthermore, beyond the canonical pro-death signals, CD95L, which can be membrane-bound or soluble, also induces non-apoptotic signaling that contributes to its tumor-promoting and pro-inflammatory roles. The intent of this review is to describe the role of CD95/CD95L in the pathophysiology of cancers, autoimmune diseases and chronic inflammation and to discuss recently patented and emerging therapeutic strategies that exploit/block the CD95/CD95L system in these diseases.

Vaccines targeting angiogenesis in melanoma

Angiogenesis has a significant role in metastasis and progression of melanoma. Even small tumors may be susceptible to metastasis and hence lead to a worse outcome in patients with melanoma. One of the anti-angiogenic treatment approaches that is undergoing comprehensive study is specific immunotherapy. While tumor cells are challenging targets for immunotherapy due to their genetic instability and heterogeneity, endothelial cells (ECs) are genetically stable. Therefore, vaccines targeting angiogenesis in melanoma are appropriate choices that target both tumor cells and ECs while capable of inducing strong, anti-tumor immune responses with limited toxicity. The main targets of angiogenesis are VEGFs and their receptors but other potential targets have also been investigated, especially in preclinical studies. Various types of vaccines that target angiogenesis in melanoma have been studied including DNA, peptide, protein, dendritic cell-based, and endothelial cell vaccines. This review outlines a number of target antigens that are important for potential progress in developing vaccines for targeting angiogenesis in melanoma. We also discuss different types of vaccines that have been investigated, delivery mechanisms and popular adjuvants, and suggest ways to improve future clinical outcomes.

Dendritic cell vaccine therapy for colorectal cancer

Colorectal cancer (CRC) remains a leading cause of cancer-related deaths in the United States despite an array of available treatment options. Current standard-of-care interventions for this malignancy include surgical resection, chemotherapy, and targeted therapies depending on the disease stage. Specifically, infusion of anti-vascular endothelial growth factor agents in combination with chemotherapy was an important development in improving the survival of patients with advanced colorectal cancer, while also helping give rise to other forms of anti-angiogenic therapies. Yet, one approach by which tumor angiogenesis may be further disrupted is through the administration of a dendritic cell (DC) vaccine targeting tumor-derived blood vessels, leading to cytotoxic immune responses that decrease tumor growth and synergize with other systemic therapies. Early generations of such vaccines exhibited protection against various forms of cancer in pre-clinical models, but clinical results have historically been disappointing. Sipuleucel-T (Provenge®) was the first, and to-date, only dendritic cell-based therapy to receive FDA approval after significantly increasing overall survival in prostate cancer patients. The unparalleled success of Sipuleucel-T has helped revitalize the clinical development of dendritic cell vaccines, which will be examined in this review. We also highlight the promise of these vaccines to instill anti-angiogenic immunity for individuals with advanced colorectal cancer.

Development and applications of a monoclonal antibody against caprine interferon-gamma

Background

Interferon-gamma (IFN-γ) is an important mediator of type I immune response and has antiviral, immunoregulatory and anti-tumor properties, plays a wide range of roles in inflammation and autoimmune diseases. The aim of this study was to obtain monoclonal antibody (mAb) against caprine IFN-γ by immunizing of BALB/c mice with the purified rIFN-γ.

Results

Recombinant caprine IFN-γ was expressed in Escherichia coli strain BL21 (DE3) and monoclonal antibodies against caprine IFN-γ were produced by immunizing of BALB/c mice with rIFN-γ. One hybridoma secreting mAb was screened by enzyme-linked immunosorbent assay (ELISA) which was designated as 2C. MAb secreted by this cell line were analyzed through ELISA, western blot and application of the mAb was evaluated by immunofluorescence analysis using goat lip tissues infected with Orf virus. ELISA analysis revealed that mAb 2C can specifically recognize rIFN-γ protein and culture supernatant of goat peripheral blood mononuclear cells (PBMCs) stimulated by concanavalin A (Con A) but cannot recognize the fusion tag protein of pET-32a. Western blot analysis showed that mAb 2C can specifically react with the purified 34.9 kDa rIFN-γ protein but does not react with the fusion tag protein of pET-32a. Immunofluorescence results demonstrated that mAb 2C can detect IFN-γ secreted in histopathological sites of goats infected with Orf virus.

Conclusions

A caprine IFN-γ-specific mAb was successfully developed in this study. Further analyses showed that the mAb can be used to detect IFN-γ expression level during contagious ecthyma in goats.

[Soluble PD-1 over-expression enhances the anti-tumor effect of senescence tumor cell vaccine against breast cancer cell growth in tumor-bearing mice]

OBJECTIVE

To investigate whether soluble PD-1 overexpression in 4T1 senescence tumor cells enhances the antitumor effect of senescence tumor cell vaccine (STCV) against breast tumor cells in a tumor-bearing mouse model.

METHODS

4T1 cells were treated with interferon-γ (IFN-γ) and the expression of PD-L1 was detected by flow cytometry. CCK8 assay was used to compare the cell proliferation activity between 4T1 cells and 4T1 cells infected by a lentiviral vector of sPD-1 (4T1/sPD-1 cells), and the expressions of sPD-1 mRNA and protein in 4T1/sPD-1 cells were detected using qPCR and Western blotting. The culture supernatant of 4T1/sPD-1 cells was added in 4T1 cells pre-treated with IFN-γ, and PD-1-positive 4T1 cells were detected with flow cytometry. Senescence β-galactosidase staining kit was used to detect the senescent 4T1 and 4T1/sPD-1 cells following exposure to X-ray radiation and Veliparib. Balb/c mice bearing subcutaneous 4T1 tumor xenografts were treated with injections of PBS, 4T1 STCV, or 4T1/sPD-1 STCV, and tumor growth was observed.

RESULTS

Stimulation with IFN-γ concentration-dependently up-regulated PD-L1 expression by as much as (84.80 ± 1.03)% in 4T1 cells (P < 0.001). sPD-1 overexpression in 4T1 cells did not significantly affect the cell proliferation. Treatment of 4T1 cells with 4T1/sPD-1 cell culture supernatant significantly increased the proportion of PD-1 + cells from (6.893 ± 0.271)% to (55.450 ± 0.555)% (P < 0.001). X-ray irradiation combined with Veliparib caused obvious senescence in 4T1 and 4T1/sPD-1 cells. In the tumor-preventing experiment, tumor formation occurred in all the mice in PBS group; 28.787% of the mice in 4T1 STCV group and 55.556% in 4T1/sPD-1 STCV group showed no tumor formation. In the tumor treatment experiment, tumor formation occurred in all the mice in PBS groups while in 4T1 STCV and 4T1/sPD-1 STCV groups, 11.111% and 38.89% of the mice were tumor-free during the observation period, respectively.

CONCLUSIONS

Senescence tumor cells vaccine has antitumor effect against breast cancer in mice, and sPD-1 overexpression can enhance this effect of the vaccine.