Arming NK cells with enhanced antitumor activity: CARs and beyond

Natural killer (NK) cells hold great promise for adoptive cancer immunotherapy. The antitumor activity of NK cells can be enhanced by the transgene driven expression of chimeric antigen receptors that facilitate the selective recognition and killing of malignant cells. Recent data from our laboratory suggest that NK cells may similarly be “armed” against neoplastic cells by the expression of cancer-specific granzyme B-containing fusion proteins that are released as soluble factors upon NK-cell activation.