[Development of novel immunotherapy targeting cancer immune evasion]

Immunotherapy has been developed as an innovative medical intervention against advanced cancer that is refractory to conventional therapies. In recent years, there have been significant advances in our basic knowledge of tumor immunology and ample experience with the clinical application of novel cancer immunotherapies. Accordingly, many of the molecular and cellular mechanisms of the interaction between cancer cells and the immune system have been elucidated. At the initial stage of cancer occurrence, the immune system constantly surveys for the emergence of cancerous cells in order to eliminate them. For cancers that have evaded immune surveillance, the immune system generates anti-tumor responses by recognizing tumor- associated antigens. In response to such immunological pressure, cancer cells edit their immunogenicity and create immunosuppressive conditions in the tumor microenvironment, resulting in cancer immune evasion. Therefore, in order to achieve effective immunotherapy, it is imperative to inactivate mechanisms used by cancer cells to evade and suppress immune responses. In this article, immune checkpoint blockade, one of the most attractive approaches in cancer immunotherapy, will be discussed.