PD-L1, also called cluster of differentiation 274 (CD274) or B7 homolog 1 (B7-H1), is a type I transmembrane protein that is widely expressed in various cell types, including tumor cells, can mainly be expressed in immune advantageous regions, including the brain and others, and has been assumed to be involved in the suppression of the adaptive arm of immune systems during particular events [167]. Here, CD274 is linked to neoplasm.