Given the mechanism of action of nivolumab and other checkpoint inhibitors currently under investigation in MPM, the fact that up to 70% of MPM patient specimens tested have been found to be programmed death-ligand 1 (PD-L1) positive8 and the role of PD-L1 as a predictive biomarker in other tumor types, there is interest in the role PD-L1 expression assessed by immunohistochemistry (IHC) may play in the relationship between treatment and clinical outcomes in MPM. Here, CD274 is linked to neoplasm.