Abstract B80: Natural killer and dendritic cells collaborate in the immune response induced by Cetuximab and IL-15 against triple negative breast cancer

Background: While the majority of Triple Negative Breast Cancer (TNBC) overexpress epidermal growth factor receptor (EGFR), EGFR inhibition as a monotherapy with Cetuximab is not effective. The study of its mechanism of action is important to find out potentially synergistic combinations. Previously, we demonstrated that Cetuximab can trigger antibody-dependent NK cell-mediated cytotoxicity against TNBC cells. The aim of this study was to investigate the effect of NK cell activation by Cetuximab-coated TNBC cells on Dendritic Cell (DC) function, and the result of its combination with IL-15. Methods: Human monocyte-derived DCs were co-cultured with autologous isolated NK cells, TNBC cells, Cetuximab and/or IL-15 for 24hs. Costimulatory molecule and activation marker expression in DC and NK cells were analyzed by flow cytometry, and cytokine concentration in culture supernatants was assessed by ELISA. DCs obtained after co-cultures were incubated for 24hs with CD40 ligand transfected fibroblasts to mimic the interaction with CD40L expressing Th cells, and IL-12 was analyzed in culture supernatants by ELISA. Results: Cetuximab treatment of TNBC cells enhanced DC maturation only when NK cells were present in the co-culture (%CD83 + : 6.6±0.7 vs 61.0±17, p Conclusions: Our results suggest that besides its anti-proliferative mechanism of action, Cetuximab has immunological effects in an in vitro model of TNBC, promoting NK cell activation and DC maturation, which could be potentiated by the combination with IL-15. This could ultimately result in the priming of T cell-based immunity, which will be evaluated in further studies. Citation Format: Estefania P. Julia, Maria Betina Pampena, Yamila S. Rocca, Jose Mordoh, Estrella M. Levy. Natural killer and dendritic cells collaborate in the immune response induced by Cetuximab and IL-15 against triple negative breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B80.