Huang RSP, Haberberger J, Severson E, et al. - This study was attempted to examine the prevalence of PD-L1 expression in a wide variety of tumor types and analyze its association with microsatellite instability, tumor mutational burden (TMB), and CD274 (PD-L1) gene amplification. Between January 2016 and November 2019, researchers conducted a retrospective analysis of all cases in which both PD-L1 immunohistochemistry (IHC) (using the DAKO 22C3 IHC assay with either tumor proportion score or combined positive score; or the VENTANA SP142 assay with infiltrating immune cell score) and comprehensive genomic profiling was investigated at Foundation Medicine. This is the largest pan-cancer analysis of relevant biomarkers correlated with the response to checkpoint inhibitors to date, including more than 48,000 cases. Future studies with treatment outcome data in individual tumor types are required to ascertain if the double-positive PD-L1+/TMB+ disease subset would respond best to immunotherapy.