Research advance in tumor specific antigens: a narrative review

Whether or not there are “tumor antigens” recognized by T cells had been controversial, until mouse and human tumor antigens have been identified one after another since the 1980s. In recent years, advances in genome sequencing technology have made possible to identify neo-antigens based on patient-specific gene mutations. Successful findings of immune checkpoint inhibitors (ICIs) in clinical trials have shed a light on tumor antigens which plays a key role so that they could be a candidate of novel therapeutic target. Since correlation between response to ICIs and neo-antigen has been clarified, it has become gradually clear that the immune response recognizing the neo-antigens plays a central role in anti-cancer immunity. Neo-antigens can elicit a strong immune response and are promising targets for novel cancer vaccine therapy or T-cell therapy, even though there are still some issues such as exhaustion and refractory state of T cells that they recognize. There are some types of tumor antigens with various specificity and immunogenicity to subject tumor. Several approaches utilizing tumor specific antigens are emerging as candidates of combination therapy together with ICI to maximize benefit from ICI treatment. Further studies of cancer antigens are expected to be the key to the next breakthrough in immunotherapy.