PDCD1 and esophageal squamous cell carcinoma: To validate the clinical impact of PES1 in ESCC patients receiving ICB therapy, we collected the samples from ESCC patients receiving anti-PD-1 (Camrelizumab from Jiangsu Hengrui Pharmaceuticals Co., Ltd, Jiangsu, China) treatment in Department of Thoracic Surgery, Shanghai Chest Hospital, Shanghai, China.