Real-World Outcomes and Prognostic Factors Among Patients with Advanced Non-Small Cell Lung Cancer and High PD-L1 Expression Treated with Immune Checkpoint Inhibitors as First-Line Therapy.

Background: Immune checkpoint inhibitors (ICIs) are standard-of-care for patients with advanced non-small cell lung cancer (aNSCLC) and programmed cell death-ligand 1 (PD-L1) expression ≥50%. Methods: A retrospective cohort study was conducted using the US de-identified electronic health record-derived Flatiron Health aNSCLC database (January 1, 2018, to July 31, 2021) among patients with PD-L1 ≥50% initiating first-line ICIs with or without chemotherapy. A clinical trial-like sub-cohort was also identified with Eastern Cooperative Oncology Group performance status 0-1, adequate organ function, and no brain metastases or other primary cancers. Kaplan-Meier methods were used to estimate time to treatment discontinuation, time to next treatment, progression-free survival and overall survival (OS) by ICI regimen (ICI+chemotherapy, ICI monotherapy) and PD-L1 expression (50-69%, 70-89%, 90-100%). Cox proportional hazard models were used to examine associations between ICI regimen, PD-L1 level, and OS, adjusting for baseline demographic and clinical variables. Results: A total of 2631 patients with aNSCLC initiating ICI+chemotherapy (n = 992) or ICI monotherapy (n = 1639) were included; median (Q1, Q3) age was 71 (63-78) years and 51.6% were male. The trial-like sub-cohort (n = 1029) generally had better outcomes vs. the overall cohort. Patients receiving ICI+chemotherapy generally had longer median OS vs. ICI monotherapy. Multivariable analyses showed no association between ICI regimen and OS among patients with PD-L1 70-89% (hazard ratio [HR]: 0.90, 95% confidence interval [CI]: 0.73-1.09) or 90-100% (HR: 0.91, 95% CI: 0.77-1.08), but patients with PD-L1 50-69% receiving ICI+chemotherapy had longer OS (HR: 0.80, 95% CI: 0.64-0.99). Conclusion: Outcomes in real-world clinical trial-like patients with aNSCLC approached those reported in pivotal ICI trials in high PD-L1 expressers. ICI monotherapy offers a potential alternative in patients with PD-L1 ≥70% while avoiding potential chemotherapy toxicity exposure; the benefits are less clear in patients with PD-L1 50-69%. Future studies should confirm these findings.