CD274 and cancer: Using these antibodiesto block PD-1 and PD-L1 has shown promising outcomes over conventionalmethods in advanced cancers.18 PD-L1, alsocalled the B7 homolog 1 (B7–H1), is expressed not only in Tcells but also in other immune cells and different types of cancer.PD-L1 is a cell surface protein expressed on activated APC, T andB lymphocytes, and other cells and is the natural ligand of PD-L2and PD-1.