Induction and characterization of neoplastic bladder tumors in a transgenic porcine model

Background Large animal models of bladder cancer are lacking. Objective This study aimed to develop and characterize a transgenic porcine model of bladder cancer (BC) using Oncopigs expressing Cre-inducible KRAS G12D and TP53 R167H mutations. Methods Eleven female Oncopigs underwent tumor induction via three cystoscopic inoculation procedures: Procedure I (N = 3, 1 inoculation/pig), chemical dissolution of the glycosaminoglycan layer with N-Dodecyl-β-d-Maltoside DDM followed by adenoviral Cre-recombinase (AdCre) instillation; Procedure II (N = 4, 3 inoculation/pig), mechanical mucosal denudation followed by AdCre instillation; and Procedure III (N = 4, 3 inoculation/pig), cystoscopy-guided submucosal injection of AdCre. Animals were clinically monitored throughout follow-up (14–28 days). Tumor development was assessed on cystoscopy and ultrasonography, and pathologically, immunohistochemically (IHC), and genomically characterized. Results All pigs remained clinically healthy. Tumors developed at 59% (16/27) of inoculation sites: nine (33%) were neoplastic and seven (26%) were inflammatory. Procedure I achieved 100% neoplastic tumors and produced both non-muscle invasive (71%) and muscle-invasive (29%) tumors. Procedure II achieved 50% neoplastic tumors, all of which were muscle invasive (100%). Procedure III generated only inflammatory tumors. Histologically, neoplastic tumors were pathologically interpreted as urothelial cell carcinomas with sarcomatoid differentiation, with IHC confirming the presence of both epithelioid and sarcomatoid features with abundant mixed leukocytic infiltrates. Genomic analyses verified Cre-induced alterations alongside other mutations seen in human BC. Conclusions We herein demonstrate an efficient and reproducible method for developing autochthonous neoplastic bladder tumors in Oncopigs that resemble human bladder cancer of varying stages. This large animal model facilitates the evaluation of novel surgical and intravesical therapies in BC.