Real-World Clinical Outcomes of Advanced Non-Small Cell Lung Cancer Patients with High PD-L1 Expression (≥ 50%) Treated with Pembrolizumab Monotherapy: Evidence from a Single University Hospital in Central Europe

SUMMARY – Pembrolizumab, a programmed death-1 (PD-1) immune checkpoint inhibitor, has demonstrated significant survival benefits as monotherapy in clinical trials for advanced non-small cell lung cancer (NSCLC) with high programmed death ligand-1 (PD-L1) expression (PD-L1 ≥ 50%). Real-world data on this topic is growing every day. We conducted a single-center, retrospective observational study at Sestre milosrdnice University Hospital Center in Zagreb, Croatia, analyzing the outcomes of patients with advanced NSCLC (stage IIIB–IV) and high PD-L1 expression treated with pembrolizumab as first-line monotherapy between March 2018 and March 2023. Demographic and clinical data including treatment response, adverse events, progression-free survival (PFS) and overall survival (OS) were analyzed using descriptive statistics and the Kaplan-Meier survival analysis, with multivariate Cox regression for covariate assessment. Seventy-two patients met the inclusion criteria. Median follow-up was 49 months. Median PFS and OS were 13 months (95% CI: 5–20 months) and 24 months (95% CI: 14–46 months), respectively. One-year OS rate was 66.67%. Pembrolizumab demonstrated a favorable safety profile, with adverse events consistent with those reported in clinical trials. This study highlights the real-world effectiveness and safety of pembrolizumab monotherapy for advanced NSCLC with high PD-L1 expression in a single-center cohort. Survival outcomes were consistent with clinical trial data.