The immune system intercepts any invading pathogens or abnormal cells within the body, including cancer cells. It has evolved numerous mechanisms to recognize such threats, all the while limiting the risk of autoimmunity or attack on normal cells and tissues. However, many cancer cells aren’t recognized as dangerous by our immune system, so bypass the body’s natural defense system, proliferate destructively, and eventually challenge the body’s ability to function. In many cancers, malignant progression is accompanied by profound immunosuppression that interferes with effective antitumor response and tumor elimination.