Pembrolizumab for recurrent locally advanced or metastatic squamous cell carcinoma of the esophagus: a drug safety evaluation

Introduction The prognosis of advanced esophageal squamous cell carcinoma (ESCC) remains poor and few effective drugs are available. Cisplatin plus 5-FU (CF) has been the standard first-line treatment for advanced ESCC. However, in the KEYNOTE-181 trial, the clinical outcomes were better in patients with programmed death ligand 1 (PD-L1)-positive advanced ESCC who received pembrolizumab, an immune checkpoint inhibitor (ICI), than in those who received cytotoxic agents as second-line treatment. Moreover, the KEYNOTE-590 trial demonstrated the superiority of pembrolizumab plus CF over CF alone in terms of overall survival. Based on the results of KEYNOTE-590, pembrolizumab plus CF has become one of the standard treatments for advanced ESCC. However, the safety profile of ICI-containing therapy is different from that of conventional cytotoxic agents.