ERBB2 and urothelial carcinoma: However, there is a clear need to further define the expression of HER2 in advanced urothelial carcinoma, assess the heterogeneity across different metastatic sites, and determine the co-expression pattern with other relevant ADC targets, such as nectin cell adhesion molecule 4 (NECTIN-4) and trophoblast cell surface antigen 2 (TROP2).