CD274 and head and neck neoplasm: Whereas cetuximab has been shown to significantly downregulate IFNγ-induced PD-L1 expression in head and neck tumor cell lines [7], tumor PD-L1 expression (< 1% versus ≥ 1%) was similar in patients with and without prior cetuximab exposure in CheckMate 141 trial [64], indicating that differences in response to nivolumab between these patient groups are not related to the effect of cetuximab on tumor PD-L1 expression.