PDCD1 and melanoma: The usefulness of PD-L1 expression as a biomarker has been reported in various large clinical trials that assessed PD-1 and/or PD-L1 inhibitors in melanoma, non–small cell lung cancer, and urothelial carcino-ma.42–44 In these studies, higher expression levels of PD-L1, as evaluated by immunohistochemistry, were predictive of response to therapy with PD-1 and/or PD-L1 inhibitors.