CD274 and esophageal squamous cell carcinoma: In the phase III study KEYNOTE-590, patients with expression of PD-L1 (CPS ≥ 10; combined positive score) showed a significant advantage in overall survival in both advanced esophageal squamous cell carcinoma and HER2 (Human Epidermal Growth Factor Receptor-2)-negative adenocarcinoma of the esophagus and gastroesophageal junction when first-line therapy with pembrolizumab was combined with cisplatin and 5-fluorouracil (5-FU) vs. chemotherapy alone (13.9 vs. 8.8 months; hazard ratio [HR]: 0.57; p < 0.0001) (Sun et al. 2021).