CD274 and esophageal squamous cell carcinoma: When the price of serplulimab was decreased by 98%, 98% and 99%, respectively, serplulimab plus chemotherapy would be absolutely dominant regimens over chemotherapy (ICER < 0) for advanced ESCC patients with PD-L1-positive, PD-L1 1 ≤ CPS < 10 and CPS ≥ 10.