(W1055) ESTABLISHMENT OF A SCREENING SYSTEM FOR THE THERAPEUTIC EFFICACY OF IMMUNE CHECKPOINT INHIBITORS USING A CO-CULTURE MODEL OF CANINE URINE-DERIVED BLADDER CANCER ORGANOIDS AND IMMUNE CELLS
Student Tokyo University of Agriculture and Technology, Japan
Abstract: Canine bladder cancer has a high prevalence of high-grade cases with a poor prognosis and innovative therapies are needed. The number of studies to determine the efficacy of immunotherapy for canine cancers is gradually increasing. Still, the number of successful cases is small, and the causes of resistance to treatment are largely unknown. Therefore, we established an evaluation system to screen the efficacy of immune checkpoint inhibitors using urine-derived canine bladder cancer Org and immune cells co-culture model. Three-dimensional canine bladder cancer Org were prepared from cancer stem cells in urine samples of bladder cancer-diseased as described before1 and their PD-L1 expression level was evaluated. Peripheral blood mononuclear cells (PBMCs) from healthy dogs were isolated using Ficoll methods and treated with concanavalin A (Con A) for 72 hours to activate T cells. Next, activated PBMCs are co-cultured with bladder cancer Org for 72 hours in the presence of the immune checkpoint inhibitors PD-1 and PD-L1, and changes were reported. Con A treatment resulted in PBMC accumulation and proliferation, and IFN-γ expression and the ratio of CD8-positive cells was increased. Additionally, the level of PD-L1 expression in canine bladder cancer Org with and without IFN-γ stimulation was different among patient-derived organoids. Furthermore, the cell viability of canine bladder cancer Org co-cultured with immune cells and treated with PD-L1 inhibitor was decreased in some canine bladder cancer organoids. In this study, we succeeded in establishing a co-culture model of canine bladder cancer Org and immune cells and evaluated the therapeutic effect of PD-L1 inhibitors. In the future, we plan to use canine PD-L1 inhibitor, caninized mouse model, and the organ-on-a-chip system to elucidate the mechanism of therapeutic resistance.
1. Elbadawy M, Usui T, Mori T, et al. Establishment of a novel experimental model for muscle-invasive bladder cancer using a dog bladder cancer organoid culture. Cancer Sci. 2019; 110: 2806–2821. https://doi.org/10.1111/cas.14118
