Cell therapy has developed rapidly. Chimeric antigen receptor-T (CAR-T)-cell therapy re-shaped therapy of many B-cell cancers including leukaemias, lymphomas and plasma cell myeloma (PCM) [1]. Despite this progress challenges remain including a complex manufacturing process (delay to availability and high cost), safety including cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS) and CAR-T-cell-related lymphomas and high cost. Many people with advanced, extensively-treated cancers potentially amenable to CAR-T-cell therapy are unable to donate sufficient T-cells to process into CAR-T-cells. These considerations are barriers to more widespread use and have prompted development of alternative cell therapies including natural killer (NK)-cells [[2], [3], [4], [5]].

NK-cell therapy is the focus of recent studies. NK-cells, part of the innate immune system, can target and eliminate cancer cells [6,7]. Decreased NK-cell function is reported in diverse haematological cancers [8]. CAR-NK-cells are being studied as a therapy for haematological cancers with encouraging early results. CAR-NK can be readily available, do not require cells from the recipient, have less CRS and ICANS are rapidly available and cost less. CAR-NK-cell-related cancers are not yet reported [9].

We discuss the biology, sources and engineering of CAR-NK-cells. We consider pre-clinical and clinical studies of CAR-NK-cell therapy of haematological cancers including B- and T-cell leukaemias and lymphomas, acute myeloid leukaemia (AML) and plasma cell myeloma (PCM). Future challenges and research directions are identified.