Novel approaches using natural killer cells in cancer therapy.

Strategies are emerging to apply natural killer (NK) cells as therapeutic agents against a broad range of malignancies. Novel clinical approaches aim to overcome limitations of original therapies, which have utilized lymphokine activated killer cells or systemic cytokine treatments. Remarkable results, including survival improvements and amelioration of graft versus host disease, were obtained with alloreactive NK cells in some cases. Other approaches in clinical evaluation include targeting heat-shock protein (Hsp) 70 expressing tumors with pre-stimulated autologous NK cells or the application of an NK cell line, NK-92, with enhanced cytolytic activity. Further mechanistic insights into NK cell cytotoxicity are a prelude to improved clinical cancer therapies.