Pembrolizumab versus chemotherapy in previously treated metastatic triple-negative breast cancer: a cost-effectiveness analysis

Pembrolizumab has demonstrated antitumor activity and a manageable safety profile in previously treated triple-negative breast cancer. In this study, the cost-effectiveness of pembrolizumab for previously treated TNBC was assessed from a US payer perspective. Three mutually exclusive states were included in the partitioned survival model to evaluate the cost-effectiveness. The modeled population and clinical outcomes were based on KEYNOTE-119. One-way sensitivity analyses and probabilistic sensitivity analysis (PSA) based on 10,000 Monte Carlo simulations were conducted to assess parameter uncertainty and the robustness of the model results. Costs, life-years, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs), incremental net health benefits (INHBs), and incremental net monetary benefits (INMBs) were analyzed. Pembrolizumab was associated with ICERs of $435,844/QALY, $329,173/QALY, and $209,069/QALY in TNBC patients with PD-L1 CPS ≥ 1, PD-L1 CPS ≥ 10, and PD-L1 CPS ≥ 20, respectively. For intention-to-treat (ITT) patients with TNBC, chemotherapy was dominant. One-way sensitivity analyses identified the cost of pembrolizumab as a significant driver. Under the base-case model assumptions, the estimated pembrolizumab price required for the ICER to reach the willingness-to-pay (WTP) threshold of $150,000/QALY was approximately $39.35/mg in patients with PD-L1 CPS ≥ 20. PSA consistently favored chemotherapy at $150,000/QALY, although the probability that pembrolizumab was cost-effective increased from 0.62% in the ITT population to 12.34% in the CPS ≥ 20 population. Pembrolizumab was unlikely to be a cost-effective option at its current price for previously treated TNBC from a US payer perspective at a WTP of $150,000/QALY.