PDCD1 and neoplasm: The poor prognosis of ESCC highlights the urgent need for improved therapies, especially novel therapeutic approaches.[11] Recently, breakthroughs in immune checkpoint blockade have offered new therapeutic options for many malignancies.[11] PD-1, also known as CD279, is a inhibitory receptor expressed on activated T and B cells, which normally function to dampen the immune response.[12–15] PD-1 is engaged by ligands PD-L1 (B7-H1, CD274) and PD-L2 (B7-DC, CD273), which are expressed by tumor cells and infiltrating immune cells.[14,16] PD-L1 is upregulated in a variety of tumor cells.