The PD-1:PD-L1 pathway has been identified as one of the important pathways for impeding effective immune responses to several human cancers, including non small cell lung cancer that was previously not thought to be a likely candidate for immunotherapy.[23], [24] It has previously been demonstrated that human PDA expresses PD-L1,[32] however the level of expression of PD-1 on T cells in PDA is not known. Here, CD274 is linked to Patent ductus arteriosus.