Immune checkpoint blockade in esophageal squamous cell carcinoma: is it ready for prime time?

Esophageal cancer is a lethal disease with limited treatment options, particularly in the metastatic setting. While the incidence of esophageal squamous cell carcinoma (ESCC) has declined worldwide, it remains a major cause of morbidity and mortality in Asia, Africa and South America (1). In contrast to esophageal adenocarcinoma, which develops in the lower esophagus and is related to gastric reflux and Barrett’s esophagus, ESCC occurs in the upper/mid esophagus and is associated with tobacco and alcohol use (2). Despite their differences, a common feature of both ESCC and adenocarcinoma is the presence of chronic inflammation and an abundance of tumorinfiltrating lymphocytes and other immune cell populations.