Editorial: NK Cell-Based Cancer Immunotherapy.

Abstract

Innate and adaptive immunity cooperate to eliminate tumors. However, when infrequent cancer cell variants are not destroyed, tumor growth and immunosurveillance enter into a dynamic equilibrium until cancer cells evade the immune system, at which point malignancies appear clinically as a consequence. Therapies designed to induce potent antitumor responses by harnessing the power of the immune system are an appealing strategy to control tumor growth. Natural killer (NK) cells are innate lymphocytes that play a pivotal role in host immunity against cancer. The activity of NK cells is finely tuned by the balance between the signals that emanate from inhibitory and activating receptors. Inhibitory receptors, such as killer-cell immunoglobulin-like receptor (KIR) and CD94/NK Group 2 member A NKG2A), recognize human leukocyte (HLA) class I molecules whose expression is often altered on tumor cells. NK cells recognize tumor cells by activating receptors, such as natural cytotoxicity receptors (NCRs) and NKG2D, which sense the changed expression of their ligands on the cancer cell surface. Providing important insights, the past 15 years have witnessed an explosion of research into the biology and clinical applications of NK cells. Current NK cell-based cancer immunotherapy aims to reverse the tumor-induced NK cell dysfunction that is observed in patients with cancer and to increase and sustain NK cell effector functions. Therapies involving NK cells may either activate endogenous NK cells or involve transfer of exogenous cells by hematopoietic stem cell transplantation (HSCT) or adoptive cell therapy