POSA141 Cost Effectiveness Analysis of Pembrolizumab Monotherapy in Advanced PD-L1 ≥50% Non-Small Cell Lung Cancer (NSCLC) in the Irish Setting

To assess the cost effectiveness of pembrolizumab monotherapy in the first line treatment of advanced programmed death ligand 1 (PD-L1) ≥50% NSCLC in the Irish health care setting. The cost-effectiveness analysis was conducted with reference to the Guidelines for Economic Evaluation in Ireland. The intervention was pembrolizumab monotherapy; the comparator was carboplatin and pemetrexed chemotherapy, and the population included those with previously untreated metastatic NSCLC with a PD-L1 status ≥50%. A de novo partitioned survival model with a progression-free, progressed disease, and death state was developed. The model had a 30-year time horizon, a one week cycle-length and the perspective was from the Irish health care service. A 4% discount rate was applied to costs and outcomes. Outcomes were expressed as an incremental cost-effectiveness ratio (ICER), measured in terms of incremental costs (IC) per quality adjusted life year (QALY). Probabilistic and deterministic sensitivity analyses were conducted. Clinical outcomes were derived from the KEYNOTE-024 trial (median follow-up 25.2 months). Parametric Methods were used to extrapolate progression-free survival and overall survival from the published Kaplan-Meier curves to the model time horizon. Costs were applied for drug acquisition, treatment initiation, administration and monitoring, adverse events, subsequent treatments, and terminal care. Costs and health state utilities were collected from Irish sources and the literature. Model outcomes suggested pembrolizumab is associated with an ICER of €59,127/QALY (IC €80,481, incremental QALY 1.36). Probabilistic sensitivity analysis estimated an average ICER of €65,998/QALY and a 1.5% chance of cost effectiveness at the Irish cost effectiveness threshold of €45,000/QALY. Outcomes were sensitive to assumptions regarding survival time, treatment acquisition costs, and the subsequent treatment costs in the chemotherapy arm. Based on the Irish cost effectiveness threshold of €45,000/QALY, pembrolizumab monotherapy is not cost effective as a first line therapy for the treatment of advanced PD-L1 ≥50% NSCLC.