Results from the KEYNOTE-181 trial (Kojima et al. 2020) showed that in patients with recurrent or metastatic ESCC with PD-L1 (CPS ≥ 10), compared with chemotherapy, pembrolizumab monotherapy prolonged overall survival (median OS: 9.3 months vs. 6.7 months) and reduced the risk of death by 36% (HR = 0.64 95% CI 0.46–0.90). This evidence concerns the gene CD274 and esophageal squamous cell carcinoma.