Administration of Autologous Dendritic Cells (DCs) Infected With an Adenovirus Expressing Her-2

We, the researchers at Hamilton Health Sciences, have developed a novel approach to cancer therapy using transfected dendritic cells (DCs) to generate enhanced immunity to defined tumor antigens. Dendritic cells are highly specialized antigen presenting cells found in the bone marrow, lymph nodes, skin and thymus. Infection of DCs with Adenovirus (Ad) vectors incorporating genes for defined tumor antigens enables intracellular expression and major histocompatability complex (MHC)-restricted presentation of tumor peptides by transfected DCs. Given the potent immunostimulatory properties of DCs and ability to use gene transfer to "load" DCs with tumor antigen, we hypothesize that administration of transduced autologous DCs may have potential therapeutic benefit as a cancer vaccine. We have examined Ad-tumor antigen DC based vaccination in murine models of breast cancer and melanoma. In both models, injection(s) of Ad-transduced DCs results in highly potent immune activation and antigen-specific anti-tumor responses. In these models, high levels of antigen-specific, cytotoxic effector lymphocytes that recognize and kill cancer cells directly correlates with a therapeutic response (tumor regression and/or complete protection of animals subsequently re-challenged with tumor cells). Animals demonstrating specific in vitro immunity are protected against subsequent injection of cancer cells. Moreover, we have observed complete resolution and significant long-term survival in animals with established metastatic disease with no demonstrable toxicity. As opposed to vaccination protocols with tumor peptides or purified epitopes that are MHC-I restricted (i.e. HLA-A2), we have found that injection of DCs transduced with a vector expressing the entire tumor antigen results in peptide presentation from both MHC-I and MHC-II complexes. The subsequent immune response is comprised of both CD4+ and CD8+ T cell populations. Thus, Ad-based gene transfer of tumor antigens appears to be a