The study will be comprised of 2 parts. The first part (dose escalation) will find the highest dose of enfortumab vedotin that does not cause unacceptable side effects in participants. The second part (dose expansion) will use the dose found in the first part to test how well the drug works.~All participants will receive enfortumab vedotin. Treatment on the study will occur during the induction and maintenance phases, and participants will enter a follow-up period after completion of the maintenance phase.
This study will test a drug called enfortumab vedotin in participants with a type of bladder cancer called non-muscle invasive bladder cancer (NMIBC).~This study will also evaluate what the side effects are and if the drug works to treat NMIBC. A side effect is anything a drug does to your body besides treating your disease.~In this study enfortumab vedotin will be put into the bladder using a catheter. A catheter is a thin tube that can be put into your bladder.