New Models for the Evaluation of Preclinical Treatment for Urothelial Carcinomas of the Upper Excretory Tract. (CICLOP)

Upper Urinary Tract Urothelial Carcinomas are rare, aggressive tumors, accounting for 5 to 10% of all urothelial tumors. These include tumors which develop in the renal cavities (renal pelvis, calices) and ureteral tumors. Nephro-ureterectomy is the standard treatment but 80% of patients will have a relapse within 2 years. Only one trial has (Birtle et al. 2020), has shown the interest of postoperative chemotherapy. Neoadjuvant systemic treatment seems particularly interesting for a population which is going to undergo a nephronic loss and therefore reduction in kidney function which is likely to make patients ineligible for cisplatin. In favor of additional immunotherapy, it has been described that upper excretory tract tumors have a high immunogenic potential with a high rate of microsatellite instability.

From surgical samples of patient tumors obtained after nephroureterectomy or biopsy material collected before treatment, we are going to generate patient-derived cell lines and xenograft models in the mouse. A recent publication has demonstrated the feasibility of this approach by specifying that the capture rate of tumor cells is 50% for patient-derived xenografts and 25% for patient-derived cells (Coleman et al. 2020). As tumors harvested from biopsies do not grow in patient-derived xenografts,we plan to graft the biopsies onto chorioallantoic chicken embryo membranes, a model which has never been used for this indication and which is one of the original features of our approach. These three concomitant approaches will allow us to increase our chances of obtaining stable upper urinary tract urothelial carcinoma lines to be used for the screening and identification of new treatments or new combinations of molecules that would benefit patients with upper urinary tract urothelial carcinomas, knowing that very few studies dedicated to this type of cancer have been conducted or published due to the rarity of the disease and the lack of existing models published on the subject of these particular tumors.

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