Dysregulation of nectin-4 levels is observed in squamous cell carcinoma of the head and neck [23], kidney cancer [24], breast cancer [6,25,26,27], ovarian cancer [28], bladder cancer [29], pancreatic cancer [7,30], gastric cancer [31], and cancer of other parts of the digestive tract [15,32,33]. This evidence concerns the gene NECTIN4 and breast cancer.