CD274 and metastatic neoplasm: However, in this case, there was PD-L1-positive expression but a lack of cytotoxic T-cell infiltration in the lung-remaining metastatic tumor, which seems to be the type (PD-L1+TIL−) that was prone to resist monotherapy of PD-1/PD-L1 inhibitors (20), giving the rationale that it did not show any response to sintilimab.