Single agent anti PD-1 inhibitors in esophageal cancer—a first step in a new therapeutic direction

Esophageal squamous cell carcinomas and adenocarcinomas have proven to be inherently resistant to systemic treatments as a result of histological, molecular and etiological heterogeneity, with limited responses seen after first line therapy. The promise of immunotherapy in esophagogastric cancer has been suggested for a long time due to the recognized link between infection, chronic inflammation, and malignancy. The emerging clinical trial data is somewhat confusing but it appears that anti programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) monoclonal antibodies do demonstrate some efficacy in a minority of gastroesophageal cancer patients with metastatic disease but with less activity when compared to melanoma or lung cancer