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

Background: Immunochemotherapy has become a new treatment for advanced esophageal squamous cell carcinoma (ESCC).

Aims: 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 And Results: Five randomized controlled trials comparing PD-1/PD-L1 based immunochemotherapy with 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. 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% confidence intervals [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).

Conclusion: In this study, treatment-related mortality was similar between immunochemotherapy and chemotherapy. 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 compared with chemotherapy.