Cost-Effectiveness of Neoadjuvant Pembrolizumab plus Chemotherapy Followed by Adjuvant Pembrolizumab in Patients with High-Risk, Early-Stage, Triple-Negative Breast Cancer in Switzerland

Aim This study assessed the cost-effectiveness of neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab versus neoadjuvant chemotherapy plus placebo followed by adjuvant placebo for patients with high-risk, early-stage, triple-negative breast cancer (TNBC) from a Swiss third-party payer perspective over a lifetime horizon (51 years). Materials and Methods A transition model with four health states (event-free, locoregional recurrence, distant metastasis, and death) was developed to assess the cost-effectiveness of pembrolizumab plus chemotherapy versus chemotherapy alone for the treatment of high-risk, early-stage TNBC. Data were utilized from the KEYNOTE-522 randomized controlled trial (ClinicalTrials.gov, NCT03036488). The incremental cost-effectiveness ratio (ICER) was calculated, which was reported as cost per life year or quality-adjusted life year (QALY) gained. A one-way deterministic sensitivity analysis, a probabilistic sensitivity analysis (PSA) and scenario analyses were conducted to assess the robustness of the model results. Results Base-case results estimated an ICER of 14,114 Swiss francs (CHF)/QALY for pembrolizumab plus chemotherapy versus chemotherapy alone. Results were most sensitive to changes in the extrapolation of event-free survival (EFS). All sensitivity and scenario analyses generated ICERs below the willingness-to-pay threshold of CHF100,000/QALY, and the PSA showed a 98.8% probability that the ICER would be below this threshold. Limitations Due to the limited follow-up period in the KEYNOTE-522 trial, EFS data were extrapolated over the lifetime horizon to inform transition probabilities. Extensive validation and scenario analyses ensured the results were robust. Conclusion The model demonstrated that neoadjuvant pembrolizumab plus chemotherapy followed by adjuvant pembrolizumab was cost-effective versus chemotherapy alone in patients with high-risk, early-stage TNBC in Switzerland.