Additional Study Information: The purpose of this study is to evaluate whether the investigational drug, BT7480, will be a safe and effective anticancer therapy. This is the first time BT7480 will be given to humans. BT7480 is designed to recognize and attach itself to both the Nectin-4 protein found on the surface of some cancer cells and CD137, a protein found on the surface of some immune cells. BT7480 binds to both Nectin-4 and CD137 and may activate immune cells to fight the Nectin-4-expressing cancers. Cancers include bladder cancer, breast cancer, esophageal cancer, ovarian cancer, head and neck/oral cancers, lung cancer, and stomach cancer.