Background: Higher PD-L1 score ≥ 50% predicts for greater benefit to immune checkpoint inhibitor (ICI) therapy in first line (1L) treatment of aNSCLC. It has recently been reported that PD-L1 score ≥ 90% predicts for even greater benefit to 1L ICI monotherapy (Aguilar et al., 2019). We examined pooled clinical trial databases to examine the relationship between high PD-L1 expression across multiple ICI monotherapies in 1L and second line (2L) treatment of aNSCLC. Methods: Data was pooled from trials (five 1L and five 2L) of ICI for the treatment of patients with aNSCLC. We defined PD-L1 score as the proportion of tumor cell stained by the assay (total of four assays identified) and included patients in the analysis with PD-L1 score ≥ 50%. Tumor-infiltrating immune cell staining was not considered. Progression-free survival (PFS) and overall survival (OS) by line of therapy for patients with PD-L1 score ≥ 90% and patients with PD-L1 score 50-89% was analyzed. Results: A total of 1320 patients treated with ICI monotherapy were identified, 873 in 1L and 447 in 2L. Median follow-up was 9.6 months in 2L patients and 13.3 months in 1L patients. Patients receiving 2L ICI therapy with PD-L1 score ≥ 90% (N = 208) had longer PFS and OS compared to patients with PD-L1 score 50-89% (N = 239), with mPFS 7.1 vs. 4.2 months (HR = 0.66 [95% CI: 0.52-0.83]) and mOS NR vs. 15.8 months (HR = 0.66 [95% CI: 0.49-0.89]). 1L ICI therapy analysis revealed similar trends, as patients with PD-L1 score ≥ 90% (N = 405) had longer PFS and OS compared to patients with a PD-L1 score 50-89% (N = 468), with mPFS 8.3 vs. 5.4 months (HR = 0.78 [95% CI: 0.66-0.92]) and mOS 22.9 vs. 16.4 months (HR = 0.74 [95% CI: 0.61-0.90]). Conclusions: This analysis showed the potential of an enhanced clinical benefit in patients with aNSCLC and PD-L1 score ≥90% across ICI monotherapies in both the 1L and 2L treatment setting. These data will be further analyzed in real world populations.