Abstract
BACKGROUND: Immunotherapy has vastly changed the treatment landscape for patients with advanced NSCLC. With high programmed death-ligand 1 (PD-L1) expression (tumor proportion score ≥50%), options include programmed cell death protein 1 or PD-L1 inhibitor with or without chemotherapy. A cut-point of greater than or equal to 50% defines PD-L1-high, but a more precise PD-L1 tumor proportion score may be an important predictor of outcomes. METHODS: We reviewed all patients with PD-L1-high NSCLC who received pembrolizumab from June 2019 to June 2021. Demographic, diagnosis, treatment, and outcomes data were collected retrospectively. The primary end point was a descriptive analysis of pembrolizumab prescribing patterns. Secondary end points included overall survival (OS) by treatment choice and absolute PD-L1 expression. RESULTS: Overall, 132 patients received pembrolizumab; 124 (94%) as monotherapy, and 8 (6%) with chemotherapy. Baseline characteristics include the following: (1) median age 70 years (50-89); (2) 55% men; (3) 79% Eastern Cooperative Oncology Group performance status 0 to 1; and (4) 96% current or former smokers. There were 39% who have PD-L1 greater than or equal to 90% versus 61% with PD-L1 of 50% to 89%. The median OS in the overall population was 14.4 months. The median OS in the pembrolizumab monotherapy cohort and combination cohort were 13.6 months and 16.6 months, respectively (p = 0.67). Within the monotherapy cohort, the median OS was longer for PD-L1 greater than or equal to 90% (19.8 mo) versus PD-L1 50% to 89% (11.9 mo, p = 0.039). The 24-month OS was 27.8% among patients with PD-L1 50% to 89% and 47.4% among patients with PD-L1 greater than or equal to 90%. CONCLUSIONS: Most patients with advanced PD-L1-high NSCLC received pembrolizumab monotherapy, among whom OS was strongly correlated with PD-L1 expression, with PD-L1 greater than or equal to 90% of patients experiencing substantially longer survival. PD-L1 expression level could be an important determinant in immunotherapy prescribing patterns and a predictor of success in advanced NSCLC.