Abstract 5689: Characterization of immune infiltrate and checkpoint protein expression patterns in murine syngeneic tumors via multiplex immunohistochemistry

Abstract

Abstract Murine syngeneic tumor models are increasingly utilized for preclinical immuno-oncology studies as immunotherapeutic strategies continue to make clinical strides. However, the immunologic features of the tumor microenvironment (TME) in these models remain largely undefined. In this study, we applied a 7-color multiplex immunohistochemistry panel to visualize and quantify the immune infiltrate within formalin-fixed, paraffin-embedded RENCA, CT26.WT, and LL/2 tumor tissues derived from subcutaneous mouse models of renal cell carcinoma, colon carcinoma, and lung carcinoma, respectively. Additionally, we applied this panel to a 4T1 orthotropic primary mammary tumor and lung metastasis formed via tail vein injection. The multiplex panel included antibodies detecting CD3 and CD8 as T cell markers, F4/80 as a myeloid cell marker, the immunosuppressive receptor PD-1 as well as its ligand PD-L1, pan-keratin as a tumor mask, and DAPI as a nuclear counterstain. We characterized the tissue localization of tumor-infiltrating immune cells and analyzed the trends in co-expression and frequency patterns of immunosuppressive proteins. This study strives to better understand the underlying differences in the immunologic landscapes of these tumors, which in turn has implications for researchers studying responses to immunotherapeutic approaches and combination strategies. Citation Format: Jennifer Ziello, Sarah Klein, Katherine Crosby. Characterization of immune infiltrate and checkpoint protein expression patterns in murine syngeneic tumors via multiplex immunohistochemistry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5689.