Biomarkers for Immune Checkpoint Inhibitors in Mesothelioma: What Are the Roles of Biomarkers for Optimal Immune Therapy?

Immunotherapy with immune checkpoint inhibitors (ICIs) has dramatically improved prognosis in various types of solid tumors. Several clinical trials have proven that ICIs have a potential to exhibit promising antitumor effects in malignant pleural mesothelioma (MPM) also. In 2018, anti-programmed cell death-1 (PD-1) antibody nivolumab was approved as a second-line treatment regimen for patients with MPM in Japan. Although ICIs have not been approved for the regulatory use in MPM in other countries to date, they are likely to be the key drugs to bring about drastic breakthrough improvement in the outcome of patients with MPM. On the other hand, ICIs do not necessarily exert favorable clinical effects. The overall response rate of ICIs is about 20%. Therefore, it is essential to select appropriate candidates for the use of ICIs. In this chapter, our discussion will focus on molecules that make reliable biomarkers that can be used to effectively select suitable candidates for ICI immunotherapy.