CD274 and neoplasm: This inconsistency could be related to tumor heterogeneity (e.g., potential differences in PD-L1 staining which can be observed between primary tumor samples and metastatic lesions, across concurrent metastatic sites, as well as within the same tissue sample), but may also be a result of discrepancies in the PD-L1 assessment methodologies that were used in the different studies [50,51].