Induction of polyclonal prostate cancer-specific CTL using dendritic cellstransfected with amplified tumor RNA

Polyvalent cancer vaccines targeting the entire antigenic spectrum on tumor cells may represent a superior therapeutic strategy for cancer patients th an vaccines solely directed against single Ags, In this study, we show that autologous dendritic cells (DC) transfected with RNA amplified from microd issected tumor cells are capable of stimulating CTL against a broad set of unidentified and critical prostate-specific Ags, Although the polyclonal CT L responses generated with amplified tumor RNA-transfected DC encompassed a s a subcomponent a response against prostate-specific Ag (PSA) as well as a gainst telomerase reverse transcriptase, the tumor-specific CTL were consis tently more effective than PSA or telomerase reverse transcriptase CTL to l yse tumor targets, suggesting the superiority of the polyclonal response. A lthough tumor RNA-transfected DC stimulated CTL, which recognized not only tumor but also self-Ags expressed by benign prostate tissue, these cross-re active CTL were exclusively specific for the PSA, indicating an immunodomin ant role of PSA in the prostate cancer specific immune response. Our data s uggest that tumor RNA-transfected DC may represent a broadly applicable, po tentially clinically effective vaccine strategy for prostate cancer patient s, which is not limited by tumor tissue availability for Ag preparation and may minimize the risk of clonal tumor escape.