Advanced urothelial cancer has no cure. But only a few chemotherapy drugs have been tested for it. The Co-eXpression ExtrapolatioN (COXEN) model predicts if cells respond to treatment. It may also help determine which drugs fight urothelial cancer based on the characteristics of a tumor. Researchers want to test if this model can choose the best therapy for advanced urothelial cancer within 3 weeks and how tumors respond to the next best therapy.