Background: Recently, several clinical studies have evaluated the first-line use of immune checkpoint inhibitors (ICIs) combined with platinum-doublet chemotherapy in patients with non-squamous non-small cell lung cancer (NSCLC), however, the differences in safety and efficacy between the various types of ICIs still require investigation. In this study, we evaluated the efficacy and safety of the first-line use of ICIs combined with platinum-doublet chemotherapy in patients with non-squamous NSCLC by meta-analysis and indirect comparison.
Methods: Literature searches were performed using PubMed, the Cochrane Library, Embase, China Knowledge Resource Integrated Database, and Wanfang Data to identify all relevant randomized clinical trials for non-squamous NSCLC after 2010. Overall survival (OS), progression-free survival (PFS), and adverse effects (AEs) were pooled for meta-analysis and indirect comparison. Subgroup analyses were conducted to examine the factors associated with PFS.
Results: The meta-analysis showed that the additional use of ICIs could significantly improve PFS and OS. The indirect comparison showed no significant difference in pembrolizumab + chemotherapy and atezolizumab + chemotherapy in the reducing of disease progression, while a significant difference in restricted mean survival time (RMST) was found between pembrolizumab + chemotherapy compared with atezolizumab + chemotherapy. A significant increase in grade ≥3 AEs was observed with the additional use of atezolizumab combined with chemotherapy. Subgroups including PD-1 status [high (>50%), intermediate (1-49%), and negative (<1%) expression], sex (male and female), smoking status (current or former smoker, and never smoked), liver metastases (with and without), age (>65 and ≤65) and Eastern Cooperative Oncology Group (ECOG) score (ECOG=0 and ECOG=1) were all associated with better PFS.
Conclusions: This meta-analysis confirmed the treatment effects of ICIs combined with chemotherapy for non-squamous NSCLC. The pembrolizumab combination group had a greater RMST benefit compared with the atezolizumab combination group. Furthermore, our study also demonstrated a PFS advantage for non-squamous NSCLC using ICIs combined with chemotherapy irrespective of programmed death-ligand 1 (PD-L1) expression level, smoking status, liver metastasis status, sex, age and ECOG score. Due to the significant increase in AEs (> grade 3), more attention should be paid to the additional use of atezolizumab.
Keywords: Non-squamous non-small cell lung cancer (non-squamous NSCLC); efficacy; first-line; immune checkpoint inhibitors (ICIs); safety.