Evaluation of particulate systems supporting tumor cell fractions in a preventive vaccination against intracranial rat glioma

The hemagglutinin-neuraminidase gene of Newcastle Disease Virus: a powerful molecular adjuvant for DNA anti-tumor vaccination

Plasmid-encoded DNA vaccine is a novel and potentially powerful tool for cancer therapy. Since the strength of immune responses induced by DNA vaccine is usually rather low, a major goal in DNA vaccine development is to enhance vaccine-induced immunity. In this study, we investigated an approach based on the use of a viral surface protein with pleiotropic function as a potential immune enhancer. To this end, we prepared bicistronic DNA plasmids encoding the hemagglutinin-neuraminidase (HN) protein of Newcastle Disease Virus in addition to a tumor target antigen. We demonstrate a higher tumor antigen-specific T cell-mediated immune response and a lower humoral response upon vaccination with a bicistronic DNA plasmid with incorporated HN gene. In a prophylactic immunization tumor model with the surrogate tumor antigen beta-galactosidase (β-gal) and in a therapeutic immunization tumor model with the xenogeneic tumor antigen human Epithelial Cell Adhesion Molecule (hEpCAM), HN gene incorporation into the DNA vaccine led to better survival and tumor regression in mice. There was also cross protection in the therapeutic tumor model against a second challenge by the parental mouse mammary carcinoma cells in mice vaccinated with the bicistronic plasmids. This is the first report describing the HN protein as an immunomodulator for enhanced antigen-specific T cell responses via DNA plasmids. The results show that co-expression of HN with a tumor target antigen through bicistronic vectors ensures precise temporal and spatial co-delivery to direct anti-tumor immune responses preferentially towards Th1.

Cancer vaccines: accomplishments and challenges

Advancements in knowledge in diverse fields of science, including genetics, cell biology, molecular biology and biochemistry, have shed light on the origins of cancer and cell intrinsic properties that allow it to grow, invade and metastasize. Many therapies currently in use or under development are based on this knowledge. Advances in immunology, on the other hand, have shed light on how the host responds to these malignant properties of cancer. Based on that knowledge, immunotherapy, in particular vaccines directed at improving the host response against cancer, is being developed as an alternative therapeutic approach. In this review, we address main issues that have driven development of cancer vaccines and the challenges that have been met and/or are anticipated.