Immune checkpoint inhibitors in esophageal cancer: Clinical development and perspectives

Esophageal cancer is the sixth most common cause of cancer-related mortality worldwide. The standard treatment for unresectable esophageal cancer is systemic chemotherapy. However, the survival benefit is limited, with a median overall survival of less than 10 months. The advent of immune checkpoint inhibitors (ICIs), including programmed cell death-1 antibodies, has revolutionized the treatment paradigm for esophageal cancer. Since demonstrating promising efficacy with manageable safety in several clinical trials, ICIs has finally reached the point where they can be used in various tumor stages in the clinical setting. ICIs are most promising treatments that can be expected to improve the prognosis in patients with esophageal cancer now and in the future. This review outlines the mechanisms, results of clinical trials, and prospects for future studies of ICIs in esophageal cancer. It also discusses clinical questions and challenges in the therapeutic development of ICIs.