MK-3120

Researchers are looking for new ways to treat people with urothelial cancer (UC) that is locally advanced or metastatic. The standard treatment for locally advanced or metastatic UC is enfortumab vedotin (EV) given with pembrolizumab. The goals of this study are to learn about: * The safety of the study treatment when given with standard treatment and if people tolerate it * The number of people who have the cancer respond (cancer gets smaller or goes away) with the new study treatment when given with standard treatment.

Researchers are looking for new ways to treat high-risk non-muscle invasive bladder cancer (HR NMIBC). NMIBC is cancer in the tissue that lines the inside of the bladder and has not spread to the bladder muscle or outside of the bladder. In standard treatment for HR NMIBC, doctors first remove the tumor with a procedure called transurethral resection of the bladder tumor (TURBT). Researchers want to learn if using MK-3120, the study medicine, can treat HR NMIBC after TURBT. The goal of this study is to learn about the safety of MK-3120 and if people tolerate it.