CD274 and neoplasm: However, patient tumors that have shown to lack PD-L1 have also responded positively to PD-1/PD-L1-targeted therapy (10, 30), suggesting that either blocking PD-L1 expression on tumors is not required for anti-tumor responses and inhibition of PD-L1 on immune cells alone may be sufficient or that more sensitive approaches to detecting PD-L1 expression on tumors is required.