Effective later-line treatment options remain an unmet medical need for patients with advanced esophageal squamous cell carcinoma (ESCC) whose disease has progressed after prior immunotherapy, particularly given the widespread use of immunotherapy in the first-line setting. This study is designed to evaluate the efficacy and safety of PD-1/IL-2α-bias bispecific antibody fusion protein monotherapy in patients with advanced or metastatic ESCC after failure of prior immune checkpoint inhibitor (ICI) plus platinum-based chemotherapy.