Abstract 495: All-in-one flow cytometry staining panel for immune-cell profiling in syngeneic tumor models

Abstract

Abstract Checkpoint inhibitor treatment has become a common therapy of various cancer types; however, clinical data indicate that only few patients respond to this regimen due to attenuated anti-tumor immune response. Thus, it has been recognized as important to consider the immune response already during preclinical drug development to anticipate such clinical drawbacks and investigate the changes of immune cell populations after treatment. Flow cytometry is widely used for this kind of analysis. However, a comprehensive analysis of numerousness immune cell populations in one tumor is a major challenge when only limited material is available due to small tumor size of e.g. a tumor responding to the treatment or analysis at an early tumor developmental stage. A staining panel that allows the analysis of all major immune cell populations in a single staining would be a major advantage. Here we present an all-in-one flow cytometry panel based on 15 colors which permits the differentiation of the main immune cell populations in the tumor, such as T cells (CD4+, CD8+, Treg), NK cells, macrophages (M1/M2), MDSCs (neutrophils, M-MDSCs) and dendritic cells. To demonstrate the value of the panel, the immune cell content of CT26wt tumors was compared after subcutaneous, orthotopic or intra-mammary fat pad implantation. During tumor growth profiling of the immune population is performed every 4 days, starting at day 7 after implantation when tumor volume is still very small (50 - 100 mm3). A comprehensive overview is given with valuable insight into the immune biology of the tumor over time and with respect to different tumor sizes. The established all-in-one staining panel allows the direct comparison of immune cell populations with a single staining which improves the development of new immune-modulating drug candidates. Citation Format: Holger Weber, Janette Beshay, Cynthia Obodozie. All-in-one flow cytometry staining panel for immune-cell profiling in syngeneic tumor models [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 495.