CTCs as tumor antigens: A pilot study using ex-vivo expanded tumor cells to be used as lysate for DC vaccines

Abstract

The global incidence and mortality rates of colorectal cancer is rising, and has surpassed lung cancer as the highest incidence of all types of cancers in Japan [1]. Standard treatments include surgery and chemotherapy, however immunotherapy using Dendritic Cell (DC) vaccines is also recognized as an effective treatment for many cancers including colorectal cancer. DCs are the most potent antigen presenting cells, which activate CD 4+/CD8+ T cells and induce cytotoxic T lymphocytes (CTLs) to attack cancer cells. Tumor antigens used in DC vaccines are typically defined tumor-derived peptides, however, using autologous tumor lysates produces significantly higher response rates [2]. It is not always feasible to obtain fresh whole tumor to use as lysate, and particularly in the case of colorectal cancer, it is difficult to collect an aseptic specimen for use. We therefore explored the possibility of producing lysate from circulating tumor cells (CTCs) that can be collected aseptically from peripheral blood. We created a model of capturing live CTCs from a colorectal cancer cell line, culturing and expanding these cells, and creating lysate from these cultured CTCs.