PDCD1LG2 and neoplasm: Interestingly, a meta-analysis comprising 19 studies showed that treatment with a PD-1 inhibitor is superior to a PD-L1 inhibitor, mostly because PD-1 inhibitors block both ligands compared to PD-L1 blockers, which allow tumor cells to escape via the PD-1–PD-L2 axis [141].