CD274 and neoplasm: ,5 Although programmed death-ligand 1 (PD-L1) expression on tumor cells is the most established biomarker to predict the efficacy of anti–programmed cell death protein 1 or anti-PD-L1 therapy for NSCLC,6, 7, 8, 9 the heterogeneity of PD-L1 expression has been reported between the primary lung tumors and metastases.10