CTLA4 and esophageal cancer: The safety and efficacy of anti-PD-1 antibodies, including pembrolizumab and nivolumab, for esophageal cancer and the anti-CTLA-4 antibodies (ipilimumab) and anti-PD-1 antibodies (nivolumab) in advanced CTLA-4 in late esophageal cancer have been significantly demonstrated in recent clinical trials (Huang and Fu, 2019).