Real‐World Outcomes of Pembrolizumab Monotherapy in Metastatic Non‐Small Cell Lung Cancer by Age and Sex: A National Population‐Based Study in Australia

Lung cancer remains the leading cause of cancer-related mortality globally. While immune checkpoint inhibitors (ICIs) are the standard of care for metastatic non-small cell lung cancer (NSCLC), real-world data from Australia are limited. We conducted a population-based cohort study using national Pharmaceutical Benefits Scheme and National Death Index data, accessed via the Australian Bureau of Statistics DataLab. Adults initiating pembrolizumab monotherapy for metastatic NSCLC (2017-2022) were included. Overall survival (OS) and time to treatment discontinuation (TTD) were assessed using Kaplan-Meier analyses and multivariate Cox regressions. Immune-related adverse events (irAEs) were inferred from incident corticosteroid and levothyroxine prescriptions. Subgroup analyses were performed by age (18-64 and ≥ 65) and sex. Among 4,334 patients, median OS was 13.2 months. Younger patients had longer OS than those ≥ 65 (17.9 vs. 12.4 months; adjusted hazards ratio [aHR] 1.29, 95% confidence interval [CI]: 1.18-1.41). Females had longer OS than males (14.8 vs. 12.1 months; aHR 0.89, 95% CI: 0.83-0.96). TTD did not differ significantly by age or sex. Incident corticosteroid and levothyroxine use occurred in 19.1% and 8.0% of patients, respectively, with higher levothyroxine use in females (9.8% vs. 6.7%, P < 0.001). In this real-world study, survival outcomes with pembrolizumab were shorter than those reported in clinical trials. Observed differences by age and sex in survival and irAE proxies suggest potential biological variation in treatment response and toxicity. These findings highlight the need for integrated clinical data to support personalized use and inform treatment strategies that improve outcomes across diverse populations.