Abstract 4231: A biobank of bladder cancer organoids as a platform for screening new therapeutic approaches

Abstract In patients with bladder cancer (BC) immune therapies have recently demonstrated an improvement for overall survival rates compared to chemotherapy alone. However, several challenges persist and it remains an unmet need to develop novel therapeutic strategies. Organoids have emerged as a promising animal-free tool revealing patients’ heterogeneity and allowing large preclinical therapeutic screening. Urosphere developed a BC organoids biobank with phenotypic, pharmacological and molecular characterization. The aim of this study was to demonstrate the relevance of our organoids models and their use for validation of therapeutic approaches such as targeted or CAR-T cell therapies using EGFR as target. Molecular characterization of the organoids was performed by exome and whole transcriptome sequencing. Cell architecture and differentiation were assessed by labeling cytokeratins (CK) 5, 17 and 20, and uroplakin 3 (UPK3). Proliferation and tumor status were validated with Ki67 and GATA3, respectively. To evaluate targeted-therapy, organoids were treated with erlotinib for 5 days and cell viability was measured with CellTiter-Glo3D® (CTG) assay. To validate CAR-T cell approach, organoids were co-cultured with anti-EGFR or control anti-CD19 CAR-T cells at 4 effector: target ratios. Cell viability was measured with CTG and Caspase-Glo® 3/7 3D assays. Pro-inflammatory and granzyme B release were analyzed by Luminex® assay. Phenotypically, organoids showed proliferating structures whose tumor status was confirmed by GATA3 expression. Cellular heterogeneity present in original tumors was also found, with differential expression of CKs showing the presence of basal (CK5/CD17) and/or differentiated superficial (CK20/UPK3) cells. Organoids from 2 models with high transcriptomic EGFR expression were selected and protein expression was confirmed by immunofluorescence. For targeted therapy, erlotinib presented significant efficacy in both models with a better activity in the model presenting the highest EGFR expression. After 48h of co-culture with anti-EGFR CAR-T cells, a decrease of cell viability associated with an increase of apoptosis was observed. After 72h of co-culture, an increase in the secretion of pro-inflammatory cytokines (IFN-γ and TNF-α) and granzyme B by anti-EGFR CAR-T cells was also observed. In co-cultures with organoids higher expressing EGFR, CAR-T cells activation appeared higher compared to those co-cultured with organoids lower expressing EGFR. Organoids reproduce characteristics of the tumor from which they are derived, making them a predictive preclinical model. In an EGFR targeting approach, the use of organoids to evaluate both targeted- and CAR-T cell therapies was validated with concordant results. This robust translational model is fully transposable to other therapeutic approaches, whether in a traditional culture model or in a co-culture system. Citation Format: Emilie Decaup, Claire Béraud, Anne Sophie Bajeot, Xavier Gamé, Nicolas Monjotin, Pascal Rischmann, Philippe Lluel, Mathieu Roumiguié. A biobank of bladder cancer organoids as a platform for screening new therapeutic approaches abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 4231.