This study is a single-center, open-label, nonrandomized phase I trial testing the safety and efficacy as well as defining the appropriate dose for future studies of Sacituzumab Govitecan and Enfortumab for people with metastatic urothelial carcinoma (mUC) progressing on platinum-based chemotherapy and PD1/L1 inhibitors~The U.S. Food and Drug Administration (FDA) has approved Enfortumab Vedotin for the treatment of metastatic urothelial carcinoma (mUC) (bladder cancer). The FDA has not approved Sacituzumab Govitecan for metastatic urothelial carcinoma (mUC) (bladder cancer) but it has been approved for other uses. The FDA has approved Sacituzumab Govitecan to treat a type of breast cancer at this time. Sacituzumab Govitecan has appeared promising in patients with bladder cancer that has spread and works by a different mechanism than Enfortumab Vedotin. Therefore, the researchers believe that combining these 2 drugs may control the cancer better than each drug does on its own.~This will be done through testing different combinations and checking for serious side effects; if there are no serious side effects a different dose combination will be explored. Once the best combination has been determined, the study will look to see how effective (how well the drug works) it is in slowing down the growth of metastatic urothelial carcinoma (mUC) progressing on platinum-based chemotherapy and PD1/L1 inhibitors and define the most appropriate level of the drugs to use for further studies.~The research study procedures include screening for eligibility, study treatment, and safety follow-up visits, in addition to general health status follow-up after study treatment.~Participants will receive study treatment for as long as they do not have serious side effects and their disease does not get worse. However, the duration may vary depending on how long the treatment works to control the cancer and how someone's body tolerates the side effects.~Immunomedics, a pharmaceutical company, is supporting this research study by providing funding for the research study, tests required for research purposes only, and the study drug Sacituzumab Govitecan.~It is expected that up to 24 people will take part in this research study.
This research study will assess what doses of Sacituzumab Govitecan and Enfortumab Vedotin can be safely combined in the treatment of metastatic urothelial carcinoma (mUC).~The names of the study drugs in this investigational combination are:~Enfortumab Vedotin~Sacituzumab Govitecan