PDCD1LG2 and esophageal squamous cell carcinoma: Ohigashi et al. studied the role of PD-L1 and PD-L2 expression in 41 human esophageal cancer resection specimens and demonstrated that expression of either PD-L1 or PD-L2 is a significant prognostic marker in patients with squamous cell carcinoma of the esophagus [13].