Cancer immunotherapy: a brief review of the history, possibilities, and challenges ahead

Abstract

The knowledge that the body possesses natural defenses to combat cancer existed long before the modern period, with multiple anecdotal reports of tumors miraculously disappearing, sometimes spontaneously or after a febrile or infectious episode. Spontaneous tumor regression of untreated malignant tumors is currently a well-accepted albeit rare phenomenon, and it is recognized that immunosuppression is associated with a higher cancer risk. The treatment of bladder carcinoma by intravesical administration of live attenuated Bacillus Calmette-Guérin bacteria was shown to be very effective in 1976 and is now standard treatment. Effective immunity against cancer involves complex interactions between the tumor, the host, and the environment. Cancer immunotherapy uses various strategies to augment tumor immunity and represents a paradigm shift in treating cancer, since attention has become more focused on the "biologic passport" of the individual tumor rather than the site of origin of the tumor. The different types of cancer immunotherapies discussed here include biologic modifiers, such as cytokines and vaccines, adoptive cell therapies, oncolytic viruses, and antibodies against immune checkpoint inhibitors, such as the co-inhibitory T-cell receptor PD-1 and one of its ligands, programmed death-ligand 1. ABSTRACT Article history: