PDCD1 and esophageal squamous cell carcinoma: Two clinical trials are ongoing with the anti-PD1 tislelizumab in combination with first-line chemotherapy consisting of fluorouracil and platinum: the phase II single-arm BGB-A317-205 trial, also including gastric and gastro-esophageal neoplasms, and the randomized phase 3 BGB-A317-306, restricted only to ESCC.