First-line pembrolizumab for advanced and metastatic non-small cell lung cancer with a PD-L1 TPS ≥ 50% at a Portuguese centre.

Objective: Pembrolizumab monotherapy is an established first-line treatment option in patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) expressing programmed death ligand 1 (PD-L1) with a tumour proportion score (TPS) ≥ 50%. However, real-life data are scarce. The aim of this study was to evaluate the effectiveness and safety of pembrolizumab in such patients and to identify predictive factors for progression-free survival (PFS) and overall survival (OS). Methods: This was a retrospective observational study of patients with advanced/metastatic NSCLC, expressing PD-L1 with a TPS ≥ 50%, treated with first-line pembrolizumab monotherapy at a Portuguese centre between January of 2017 and December of 2023. We assessed PFS, OS and safety. Results: Of the 101 patients included, 67.3% were men, 92.1% were White, 89.1% had a performance status 0-1, 76.2% had a non-squamous histology and 90.1% had metastatic disease. The median age was 65 years. The median PFS and OS were 11.0 months (95% CI: 7.03-14.97) and 15.0 months (95% CI: 10.81-19.19), respectively. Immune-mediated adverse events occurred in 31.7% of the cases. Multivariate analysis identified squamous histology as a negative predictive factor for PFS (HR = 2.60; 95% CI: 1.48-4.50; p = 0.001) and OS (HR = 2.28; 95% CI: 1.30-3.97; p = 0.004) and showed brain metastases to be associated with shorter OS (HR = 1.98; 95% CI: 0.90-4.36; p = 0.026). Conclusions: This study supports the effectiveness and safety of first-line pembrolizumab monotherapy in patients with advanced/metastatic NSCLC expressing PD-L1 with a TPS ≥ 50%, highlighting the disparity of outcomes according to histology.