In addition, IHC staining for PD-L1 revealed that gefitinib combined with pemetrexed significantly downregulated the expression of PD-L1 in xenograft tumor tissues (Fig. 7F), indicating that the combination treatment presumably reversed gefitinib-resistance in PD-L1 overexpression cells via inhibiting the expression of PD-L1. Here, CD274 is linked to neoplasm.