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.