For example, PD-L1 expression is commonly (>50% of cases) seen in peripheral T-cell lymphomas (PTCL) such as NK/T-cell lymphoma (NKTCL), angioimmunoblastic T-cell lymphoma (AITL), and anaplastic lymphoma kinase (ALK)-negative anaplastic large cell lymphoma (ALCL) [194,195]. This evidence concerns the gene ALK and mature T-cell and NK-cell non-Hodgkin lymphoma.