This hypothetical first-in-human study is designed to evaluate the safety, feasibility, and preliminary anti-tumor activity of an allogeneic dual-target Nectin-4/HER2 CAR-NK cell product in adults with relapsed/refractory locally advanced or metastatic urothelial carcinoma. Based on public urothelial-cancer evidence, Nectin-4 was selected as the lead antigen because it has the strongest disease-specific clinical validation; HER2/ERBB2 was chosen as the secondary co-target to broaden tumor coverage and reduce antigen-escape risk. EpCAM is not selected as a therapeutic co-target in this example because of broader normal epithelial expression and weaker tumor specificity in urothelial carcinoma.