This clinical trial is focused on studying a type of cancer called Invasive Urothelial Carcinoma, which is a cancer that affects the bladder and other parts of the urinary system. The study is comparing a treatment using a medication called Nivolumab with a placebo. Nivolumab is a type of medication that is given through an infusion, which means it is delivered directly into the bloodstream through a vein. The purpose of the study is to see how well Nivolumab works in preventing the cancer from coming back after surgery.

Participants in the study will be randomly assigned to receive either Nivolumab or a placebo. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual medication and who is receiving the placebo. This helps ensure that the results are not biased. The study will take place over a period of time, and participants will receive regular infusions and check-ups to monitor their health and the status of their cancer.

The main goal of the study is to compare the time participants remain free of cancer between those receiving Nivolumab and those receiving the placebo. Additionally, the study will look at other outcomes, such as how long participants live without the cancer spreading to other parts of the body and overall survival rates. This research aims to provide valuable information on the effectiveness of Nivolumab in treating high-risk Invasive Urothelial Carcinoma.