Current international guidelines, such as those from the National Comprehensive Cancer Network (NCCN) and the European Society for Medical Oncology (ESMO), recommend immunotherapy targeting the programmed cell death protein 1 (PD-1) or its ligand (PD-L1) in combination with chemotherapy as a standard first-line treatment option for advanced or metastatic ESCC, and as monotherapy in subsequent lines, based on results from landmark clinical trials (3, 4). This evidence concerns the gene PDCD1 and esophageal squamous cell carcinoma.