Cost-effectiveness and Value-based Pricing of Trastuzumab Deruxtecan in Metastatic Breast Cancer With Low HER2 Expression.

Background: Recently, the DESTINY-Breast04 trial revealed that trastuzumab deruxtecan (T-DXd) significantly prolonged overall survival in patients with human epidermal growth factor receptor 2 (HER2)-low metastatic breast cancer (MBC). Considering the extraexpensive price of the new drug, a cost-effectiveness analysis of T-DXd is necessary to perform in the United States. In addition, because T-DXd has not been marketed in China, the pricing is a very important driver for the cost-effectiveness of T-DXd. The range of drug costs for which T-DXd could be considered cost-effective from a Chinese healthcare system perspective was explored.

Methods: We developed a Markov model to evaluate the cost-effectiveness of T-DXd versus physician's choice of chemotherapy (PCC). The simulation time horizon for this model was the life-time of patients. Transition probabilities were based on data from the DESTINY-Breast04 trial. Health utility data were derived from published studies. Outcome measures were costs (in 2022 US$), life-years (LYs), quality-adjusted LYs (QALYs), and the incremental cost-effectiveness ratio (ICER). One-way and probabilistic sensitivity analyses assessed the uncertainty of key model parameters and their joint impact on the base-case results.

Results: The model predicted that T-DXd provided an improvement of 0.84 LYs and 0.58 QALYs compared to PCC, with an ICER of $259,452.05 per QALY in the United States and $87,646.40 per QALY in China. The one-way sensitivity analysis demonstrated that the price of T-DXd had the greatest impact on ICERs. Probabilistic sensitivity analysis predicted that the probabilities of T-DXd being cost-effective compared to PCC were 7.2% and 0% at a willingness-to-pay of $150,000 per QALY in the United States and $36,475 per QALY (3 times the per capita gross domestic product) in China, respectively. Subgroup analyses showed that T-DXd was more effective for patients without visceral disease at baseline, followed by patients with Asian ethnic, patients without prior CDK 4/6 inhibitors therapy, and patients with HER2-1+ (IHC detection) status.

Conclusion: T-DXd was unlikely to offer a reasonable value for the money spent compared to PCC for patients with HER2-low MBC in the United States. A value-based price for T-DXd was reduced by 51% in the United States and less than $1950 per cycle in China.