PD-L1 was assessed in formalin-fixed, paraffin-embedded archival tumor samples at a central laboratory using a prototype immunohistochemistry assay and the 22C3 antihuman PD-1 antibody (Merck and Co., Kenilworth, NJ).24 positivity was defined as PD-L1 expression in the stroma or in ≥1% of tumor cells. Here, CD274 is linked to neoplasm.