Pembrolizumab prevents Hodgkin’s lymphoma cells from evading immune destruction by blocking the interaction between the T cell regulatory protein programmed cell death-1 (PD-1) and its ligands, programmed cell death ligand 1 (PD-L1) and programmed cell death ligand 2 (PD-L2). This evidence concerns the gene PDCD1LG2 and Hodgkins lymphoma.