PD-1/PD-L1 based immunochemotherapy vs chemotherapy alone for advanced esophageal squamous cell carcinoma: a meta-analysis focus on PD-L1 expression level

Objective: Immunochemotherapy has become a new treatment for advanced esophageal squamous cell carcinoma (ESCC). We aimed to study the clinical efficacy and toxicity of immunochemotherapy based on PD-1/PD-L1 compared with chemotherapy alone in the treatment of advanced ESCC, focusing on analyzing the influence of PD-L1 expression level. Methods: Randomized controlled trials comparing PD-1/PD-L1 based immunochemotherapy wirh chemotherapy alone for advanced ESCC were included. We extracted efficacy data [objective response rate (ORR), disease control rate (DCR), overall survival (OS) rate, progression-free survival (PFS) rate] and safety data (treatment-related adverse events, treatment-related mortality) and performed meta-analyses. Results: 5 articles were included. Compared with chemotherapy alone, the ORR and DCR of immunochemotherapy increased by 2.05 times and 1.54 times, respectively. Overall, patients receiving immunochemotherapy had a significant long-term survival advantage [OS: hazard ratio (HR)=0.68, 95% hazard ratio (CI) 0.61-0.75; PFS: HR=0.62, 95%CI 0.55, 0.70, respectively]. Even with PD-L1 tumor proportion score <1%, immunochemotherapy also showed a significant survival advantage [OS: HR=0.65, 95%CI 0.46-0.93; PFS: HR=0.56, 95%CI 0.46-0.69, respectively]. However, for PD-L1 combined positive score (CPS)<1, the survival advantage of immunochemotherapy was not significant [OS: HR=0.89, 95%CI 0.42-1.90; PFS: HR=0.71, 95%CI 0.47-1.08, respectively]. The toxicity of immunochemotherapy was higher than that of chemotherapy alone, but there was no statistical difference in treatment-related mortality (odds ratio=1.11, 95%CI 0.67-1.83). Conclusions: In this study, PD-1/PD-L1 based immunochemotherapy significantly could improve survival outcomes in patients with advanced ESCC. For patients with CPS<1, the survival advantage of immunochemotherapy was not significant. The toxicity of immunochemotherapy was acceptable.