PVR and cancer: DNAM-1 ligands PVR and Nectin-2 have been described to be absent or very scarcely expressed in normal tissue [proteinatlas.org and (73, 77)], so their targeting should hypothetically not be toxic; however, the differential expression of DNAM-1 ligands in cancer versus normal cells does not exclude a possible toxicity mediated by DNAM-1 chimeric receptor-engineered NK cells, which should be carefully explored by preclinical studies.