Therefore, a substantial proportion of patients with ESCC can benefit from second‐line PD‐1 inhibitor monotherapy and also demonstrate good tolerance to the subsequent chemotherapy, suggesting the possibility of optimizing PD‐1 inhibitor‐based second‐line treatment strategies to further enhance the efficacy beyond PD‐1 inhibitor monotherapy alone. Here, PDCD1 is linked to esophageal squamous cell carcinoma.