Abstract 3661: The impact of tumor-infiltrating natural killer cells on ovarian cancer progression

Abstract

Abstract Cancers adopt diverse strategies to safeguard their survival by evading tumor surveillance. Natural killer (NK) cells and CD8 T-lymphocytes are capable of destroying tumor cells thus playing a critical role in tumor immunity. In previous studies, we showed that NK cell derived TRAIL is essential for the cytotoxic activity of the DR5 agonistic antibody AD5-10, since depletion of NK cells abolished the antitumor activity of AD5-10 in a xenograft ovarian cancer (OC) mouse model. In the present study, we investigated whether NK cells are associated with clinical outcome as well as with the immune infiltrate showing anti-tumor immunity in OC. We analyzed NK cell infiltration in human primary ovarian tumor tissues using immunohistochemical analysis of a representative population of OC patients on a tissue microarray. NK tumor-infiltrating cells were detected within tumor tissues, whereas CD3 tumor-infiltrating T-lymphocytes were almost undetectable. NK cells in addition inversely correlated with FIGO stage (r=−0.51, p<0.001) and tumor grade (r=−0.3, p=0.03). These data indicate that the presence of intratumoral NK cells correlates with improved clinical outcome in OC. When we analyzed the cytotoxic capacity of human NK cells against OC cells in vitro, we found that human NK cells were capable to induce apoptosis in a concentration-and time-dependent manner in several OC cell lines. Interestingly, the addition of the DR5 agonistic antibody AD5-10 sensitized TRAIL resistant OC cell lines to NK cells mediated cytolysis. To study tumor surveillance of OC in vivo, we are currently setting up mouse models. Transformed murine ovarian surface epithelial (MOSE) cell lines derived from C57BL/6 mice have been implanted intraperitoneally into syngenic wild type, RAG2 -/-, RAG2 -/- γ -/-, NK depleted, CD8 depleted C57BL/6 recipient mice. The outcome of these studies will be presented. In summary, our findings point at a critical role for NK cell mediated tumor surveillance for OC development. Importantly, NK cell infiltration correlates with prognosis in human ovarian carcinoma. Thus, our study may open novel therapeutic opportunities by interfering with host immunity in the future. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3661. doi:10.1158/1538-7445.AM2011-3661