Differential Efficacy of Pembrolizumab According to Metastatic Sites in Patients With PD-L1 Strongly Positive (TPS ≥ 50%) NSCLC

Background Pembrolizumab has shown significantly better efficacy than platinum doublet chemotherapy in patients with programmed cell death ligand 1 (PD-L1) strongly positive (tumor proportion score ≥ 50%) non–small-cell lung cancer (NSCLC). However, the predictors of response to pembrolizumab have not yet been fully elucidated for patients with PD-L1 strongly positive NSCLC. Patients and Methods We retrospectively analyzed 145 patients who had been treated with pembrolizumab for PD-L1 strongly positive (TPS ≥ 50%) NSCLC without an EGFR (epidermal growth factor receptor) mutation or ALK rearrangement from February 2017 to March 2020. Various clinical characteristics, including Eastern Cooperative Oncology Group performance status, treatment line, PD-L1 expression, C-reactive protein level, neutrophil/lymphocyte ratio, and metastatic sites, and the clinical outcome of pembrolizumab treatment were examined. Results Patients with higher PD-L1 expression (≥ 75%; n = 90) had a higher objective response rate (ORR) and longer progression-free survival (PFS) compared with those with lower expression (50%-74%; n = 55; ORR, 51% vs. 33%; P = .0305; median PFS, 13.9 months vs. 5.2 months; P = .0111). In addition, 15 patients with liver metastasis (LM) had a significantly lower ORR and shorter PFS than the 130 patients without LM (ORR, 20% vs. 47%; P = .0468; median PFS, 3.4 months vs. 9.4 months; P = .0018). A multivariate analysis indicated that PD-L1 expression and LM were significant predictors of PFS after pembrolizumab treatment (higher PD-L1 expression: hazard ratio, 0.58; 95% confidence interval, 0.38-0.91; P = .0183; presence of LM: hazard ratio, 2.05; 95% confidence interval, 1.03-3.82; P = .0420). Conclusion PD-L1 expression and LM status were predictors of the efficacy of pembrolizumab in patients with PD-L1 strongly positive NSCLC.