Immunotherapy involves understanding and harnessing the relationship between the immune system and cancer cells to combat oncogenesis. There are many different potential immunotherapeutic approaches, including cell-based strategies such as adoptive cell transfer, receptor pathway-based strategies such as checkpoint inhibition, and agent-based approaches such as antibody therapy. Genetic engineering can be incorporated into all of these approaches. Gene editing can be used to modulate receptor expression levels, induce the production of certain molecules, change cellular phenotypes, or alter the general intensity of the immune response.