Li et al. utilized human-derived induced pluripotent stem cells (iPSCs) to generate NK cells engineered with chimeric antigen receptors (CARs) specifically designed for NK cells with the NKG2D transmembrane domain, the 2B4 costimulatory domain, and the CD3ζ signaling domain to support antigen-specific NK cell activation and cytotoxicity. In an murine xenograft model of human ovarian cancer, the CAR-expressing iPSC-derived NK cells outperformed other NK cell variants in antitumor activity. Persistence and tumor control were comparable to that of CAR T cells, however, the modified NK cells were substantially less toxic and prolonged survival.
Chimeric antigen receptors (CARs) significantly enhance the anti-tumor activity of immune effector cells. Although most studies have evaluated CAR expression in T cells, here we evaluate different CAR constructs that improve natural killer (NK) cell-mediated killing. We identified a CAR containing the transmembrane domain of NKG2D, the 2B4 co-stimulatory domain, and the CD3zeta signaling domain to mediate strong antigen-specific NK cell signaling. NK cells derived from human iPSCs that express this CAR (NK-CAR-iPSC-NK cells) have a typical NK cell phenotype and demonstrate improved anti-tumor activity compared with T-CAR-expressing iPSC-derived NK cells (T-CAR-iPSC-NK cells) and non-CAR-expressing cells. In an ovarian cancer xenograft model, NK-CAR-iPSC-NK cells significantly inhibited tumor growth and prolonged survival compared with PB-NK cells, iPSC-NK cells, or T-CAR-iPSC-NK cells. Additionally, NK-CAR-iPSC-NK cells demonstrate in vivo activity similar to that of T-CAR-expressing T cells, although with less toxicity. These NK-CAR-iPSC-NK cells now provide standardized, targeted "off-the-shelf" lymphocytes for anti-cancer immunotherapy.