Abstract 585: Induction of immunogenic cell death and enhancement of dendritic cell function: Development of anin vitro,ex vivoICD platform for the identification of novel ICD inducers

Immunological cell death (ICD) is a form of cancer cell death induced by radiotherapy, photodynamic therapy and a few chemotherapeutic agents such as Doxorubicin, Mitoxantrone, and Oxaliplatin. Unlike apoptosis or necrosis, ICD can induce an effective immune response directed against the tumor whereby both dendritic cells and T lymphocytes are mediators of this response. Dying cancer cells recruit and activate immune cells by releasing damage-associated molecular patterns (DAMPS) that help and promote the immune response to antigenic tumor neo-epitopes. Three key DAMPS are associated with the ICD process: calreticulin exposition on the cell surface, ATP secretion and high-mobility group box 1 (HMGB1) release. Using our in-house developed screening strategy facilitated by an automated in vitro platform with four assays, we have identified and characterized six cell lines (human breast MDA-MB-436 and MDA-MB-231, human osteosarcoma U-2 OS, murine pancreas Pan02, murine colon CT26, murine liver Hepa 1-6) for the three key DAMPs and cell viability. Furthermore, the screening of Oncodesign's Nanocyclix® library using the ICD bona fide cell lines described above resulted in the identification of ODS2006336, a potential in vitro ICD inducer. As dendritic cells (DCs) play a key role in the recognition of DAMPs associated with ICD and the subsequent uptake and presentation of tumor antigens, we examined the phagocytosis of ICD inducer-treated tumor cells by DCs. ICD inducer-treated CT26 cells when cultured with spleen-derived DCs were efficiently phagocytosed by DCs. An increase in IL-1β secretion in the co-culture supernatant was observed. IL-1β plays an important role in anti-tumor T cell priming. In addition, pro-inflammatory cytokines IL-6 and TNFα that promote T cell differentiation and NK cell activation were also detected. Increased secretion of IL-12 by activated DCs can also enhance NK cell functionality. Thus, ICD activates both innate and adaptive arms of the immune system. With respect to cancer immunotherapy, the ICD process elicits enhanced adjuvanticity and antigenicity from dying cancer cells and consequently, promotes the development of clinically desired antitumor immunity. In essence, we describe a novel strategy for the identification of ICD inducers within large chemical libraries followed by a streamlined ex-vivo co-culture assay to demonstrate enhanced DC function.Citation Format: Akanksha Gangar, Didier Grillot, Raphaelle Guillard-Huet, Jean-Francois Mirjolet, Fabrice Viviani. Induction of immunogenic cell death and enhancement of dendritic cell function: Development of an in vitro, ex vivo ICD platform for the identification of novel ICD inducers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 585.