Natural Killer Cells: A Promising Cellular Therapy Platform to Conquer Cancer

Natural killer (NK) cells are a class of lymphocytes that is part of the innate immune response with both antiviral and anti-tumor effects in a non-antigen specific manner. As NK cells in cancer patients are dysfunctional or reduced in number, adoptive transfer of cytolytic NK cells to exploit their antitumor potential is currently being explored. NK cells can be derived from several sources including peripheral blood, umbilical cord blood, as well as hematopoietic stem cells. NK cells have the advantage of not being associated with the development of graft-versus-host-disease which would theoretically make them the ideal allogeneic product. However, there are several limitations that have traditionally faced NK based cellular therapy. In the following chapter, we will present strategies and advances that have been developed to overcome these limitations, including increasing their persistence in vivo, improving their homing to the tumor and overcoming the immunosuppressive effects of the tumor microenvironment. We will also discuss the development of chimeric antigen receptor (CAR) NK cells, their efficacy and safety profile, and results from early clinical trials.