CD274 and esophageal squamous cell carcinoma: SHR-1210 is a new, fully humanized anti-PD1 monoclonal antibody that was tested in a monotherapy in 30 ESCC patients with advanced/metastatic disease as a second-line therapy, achieving 33% objective responses: objective responses were more common among patients with PD-L1-positive tumors with > 5% positive cells and high tumor mutational burden [107].