Retrospective analyses have shown that PD-L1 positivity in tumor cells, as detected by immunohistochemistry, may predict an improved response to anti-PD-1/PD-L1 therapy in melanoma (29), non-small-cell lung carcinoma (30), breast cancer (31), esophageal adenocarcinoma (32), glioblastoma (33), renal cell carcinoma (34), pancreatic carcinoma (35) and urothelial carcinoma (36). This evidence concerns the gene CD274 and breast cancer.