CD274 and extranodal nasal NK/T cell lymphoma: It has been reported that PD-L1 overexpression was suggested as a potential biomarker for PD-1/PD-L1 targeting therapy in some solid malignancies (30) and PD-L1 is highly expressed in EBV-LPD pathological tissues (15–17), but previous studies showed whether PD-L1 expression could be a potential biomarker to predict response to PD-1/PD-L1 inhibitors are still largely undefined in relapsed/refractory NK/T-cell lymphoma (19, 21, 31, 32).