Fig. 3.

Using the innate effector lymphocyte natural killer (NK) cell, potential immunotherapeutic techniques for cancer treatment have been identified. 6 major strategies are highlighted to increase the effector activity of NK cells and assist in the targeting of cancer cells. Some are clinically licensed, such as cytokines and immune checkpoint inhibitors, whereas others are still in the pre-clinical stage. To improve the effectiveness of these therapies in solid tumors, further research is required [39].