NECTIN4 and cancer: Certain cancer cells or cell lines, such as breast, lung and ovarian cancers, have been found to overexpress nectin-4.3–5 Nectin-4 is also known to be cleaved by a disintegrin and metalloproteinase (ADAM) proteases and shed into the bloodstream.6 Indeed, soluble forms of nectin-4 have been identified at high levels in the serum of cancer patients, and it has been suggested as a new biomarker of these cancer types.3,4,6,7 More recently, nectin-4 has exhibited characteristics as a potential target for cancer therapy.