NEO-201 activity in restoring NK cell cytotoxicity decreased when carcinoma cell lines with a lower level of CEACAM5+/NEO-201+ cells were used as targets, suggesting that NEO-201-mediated enhancement of NK killing is directly correlated with the level of cells expressing the variant form of CEACAM-5 recognized by NEO-201 [31]. This evidence concerns the gene CEACAM5 and carcinoma.