Immune microenvironment to predict response of cancer chemotherapy and radiotherapy

Abstract

Chemotherapy and radiotherapy are conventional cancer treatments widely applied in clinics, but their response rate is generally very limited. Because they also cause various toxic events, "precision medicine" to select patients who are likely to respond and to exclude patients who are likely to have severe adverse reactions is critically important. Emerging evidence has implicated the critical functions of the immune microenvironment in determination of therapeutic responses to chemotherapy/radiotherapy. In particular, tumor-infiltrating T lymphocytes (TILs) are often observed in solid tumors and appear to have a strong correlation with the clinical outcome of cancer patients. However, tumor immunity is composed of a complex network between anti-tumoral and pro-tumoral immune cells. In addition, the immunogenicity of cancer cells is enormously different between individual tumors or within a tumor because of genetic somatic alterations as well as the antigen-presentingmachinery in tumor cells. It is therefore imperative to assess quantity and clonality of a subset of TILs in a comprehensive manner for the development of a better prediction system to chemo/radiotherapy. This chapter discusses predictive potentials of comprehensive analysis of TILs, including how to intensively characterize TILs and the future perspectives before translation into clinical applications.