Application of natural killer immunotherapy in blood cancers and solid tumors.

PURPOSE OF REVIEW: Natural killer (NK) cells are innate lymphoid cells characterized by their ability to attack aberrant and cancerous cells. In contrast to the activation of T-cells, NK cell activation is controlled by the interaction of NK cell receptors and their target cells in a manner independent of antigen organization. Due to NK cells' broad array of activation cues, they have gained great attention as a potential therapeutic agent in cancer immunotherapy. RECENT FINDINGS: Ex vivo activation, expansion, and genetic modifications, such as the addition of a chimeric antigen receptor (CAR), will allow the next generation of NK cells to enhance cytotoxicity, promote survival, and create "off-the-shelf" products. In addition to these that are poised to greatly enhance their clinical activity, the inherent lack of potential for causing graft-versus-host disease (GVHD) and cytokine release syndrome (CRS) suggest that CAR NK cells have the potential to be complementary to CAR-T cells as a component of therapeutic strategies for cancer. SUMMARY: In this review, we will provide a general understanding of NK cell biology, CAR-NK cell advantages over CAR-T cell therapy, barriers to making NK cell immunotherapy viable, and current NK cell clinical trials for hematological malignancies and solid tumors. The next generation of NK cells has potential to change the circumstances guiding present cancer immunotherapies.