PD-L1 expression as a prognostic marker in patients treated with chemotherapy for metastatic non-small-cell lung cancer.

Background: In metastatic non-small-cell lung cancer (mNSCLC), PD-L1 expression is associated with benefit from immune checkpoint inhibitor (ICI) therapy. However, the significance of PD-L1 expression in chemotherapy-treated patients is uncertain. Methods: Using the chemotherapy control arm of first-line randomized trials, a meta-analysis of the association between efficacy outcomes and PD-L1 status was performed, stratified by assay due to inter-assay differences. Results: Across 12 trials and 4378 patients, overall survival (OS) was superior in high PD-L1 versus negative tumors and low versus negative according to 22C3/28-8 assays. When classified by SP142 assay, no significant difference in response or survival was seen between PD-L1 groups. Conclusion: In mNSCLC, high PD-L1-expressing tumors are associated with longer OS and improved objective rate when treated with chemotherapy. Inter-assay variability impacts outcome results.