Dendritic Cell-Mediated Cross-Presentation of Antigens Derived from Colon Carcinoma Cells Exposed to a Highly Cytotoxic Multidrug Regimen with Gemcitabine, Oxaliplatin, 5-Fluorouracil, and Leucovorin, Elicits a Powerful Human Antigen-Specific CTL Response with Antitumor Activity in Vitro

Gemcitabine, oxaliplatin, leucovorin, and 5-fluorouracil (GOLF) is a novel multidrug regimen inducing high levels of necrosis and apoptosis in colon carcinoma cells. This regimen is also able to promote a process of Ag remodeling including up-regulation of immunotherapy targets like carcinoembryonic Ag (CEA), thymidylate synthase (TS). We have conducted a preclinical study aimed to investigate whether these drug-induced modifications would also enhance colon cancer cell immunogenicity. Several CTL lines were thus generated by in vitro stimulating human HLA-A(*)02.01(+) PBMCs, from normal donors and colon cancer patients, with autologous dendritic cells cross-primed with cell lysates of colon cancer cells untreated, irradiated, or previously exposed to different drug treatments including the GOLF regimen. Class I HLA-restricted cytolytic activity of these CTL lines was tested against colon cancer cells and CEA and TS gene transfected target cells. These experiments revealed that CTLs sensitized with GOLF-treated cancer cells were much more effective than those sensitized with the untreated colon carcinoma cells or those exposed to the other treatments. CTL lines sensitized against the GOLF-treated colon cancer cells, also expressed a greater percentage of T-lymphocyte precursors able to recognize TS- and CEA-derived peptides. These results suggest that GOLF regimen is a powerful antitumor and immunomodulating regimen that can make the tumor cells a suitable means to induce an Ag-specific CTL response. These results suggest that a rationale combination of GOLF chemotherapy with cytokine-based immunotherapy could generate a chemotherapy-modulated Ag-specific T-lymphocyte response in cancer patients able to destroy the residual disease survived to the cytotoxic drugs.