KLRK1 and colorectal cancer: Lenalidomide, a 4-amino-glutamyl analogue of thalidomide used as an immunomodulatory drug with potent clinical anti-neoplastic efficacy in solid tumors, significantly increases cytotoxic activity of a second-generation NKG2D-CAR-T cells against colorectal cancer cell lines, HCT116 and SW480 (40).