Current status of cancer immunotherapy with immune checkpoint inhibitors

Abstract

The clinical outcome in advanced cancer has improved since the development of targeted therapies and immune checkpoint inhibitors. We can expect better overall survival after a combination treatment with these therapeutic agents. Classical cytotoxic chemotherapeutic agents directly kill tumor cells by destroying the cell structure and DNA of tumor cells or inhibiting their metabolism. Targeted therapy also directly affects tumor cells by inhibiting the cell growth signaling system. Conversely, immune checkpoint inhibitors can enhance immune responses by using the host immune system in the tumor microenvironment, leading to the direct killing of tumor cells. Therefore, immune checkpoint inhibitors are less toxic and have longer response durations. Even in solid tumors with nonimmunogenic backgrounds, cytotoxic chemotherapy or targeted treatment can induce immune responses to place the tumor microenvironment in an immunogenic state. Synergistic anticancer effects can be expected when immune checkpoint inhibitors are added during this state. Moreover, drug resistance may be overcome by combination therapies. If patients with cancer are treated with a combination of these therapeutic agents and the characteristics of each tumor are identified with data from next generation sequencing, personalized treatments can be tailored, making it possible to control cancers as a curable disease just like other benign chronic diseases.