Additionally, constitutive activation of the STAT3 pathway and overexpression of the viral oncoprotein LMP1 induce upregulation of PD-L1 in ENKTCL, contributing to the tumor escape from cytotoxic T-cell activity, which has been an important biological rationale to support the development of tests with immune checkpoint inhibitors in relapsed and refractory ENKTCL (70, 89, 90). Here, CD274 is linked to neoplasm.