OBJECTIVES: This study examined the cost-effectiveness of capivasertib plus fulvestrant versus fulvestrant monotherapy in patients with HR+/HER2- advanced/metastatic breast cancer (ABC/MBC) who had disease progression during or after previous endocrine therapy in the US healthcare setting.

METHODS: A cost-effectiveness analysis was conducted using a partitioned survival model with three health states: progression-free disease (PFD), progressive disease (PD), and death, over a 5-year time horizon from a US payer’s perspective. Progression-free survival (PFS) and overall survival (OS) data were derived from the FAKTION trial. Utility, disutility, and cost data were obtained from published literature and the Centers for Medicare and Medicaid Services (CMS). Capivasertib cost was based on WAC price. Costs were presented in 2023 US dollars. Both costs and effectiveness were discounted by 3%. The incremental cost-effectiveness ratio (ICER) was calculated to compare the two treatment strategies with a willingness-to-pay (WTP) threshold of $150,000 per quality-adjusted life-year (QALY). Sensitivity analyses were performed to examine parameter uncertainty. A scenario analysis was performed to explore the impact of varying the monthly cost of capivasertib.

RESULTS: In base case analysis, capivasertib + fulvestrant was more effective (1.71 vs. 1.30 QALYs) and more costly ($312,295 vs. $249,697) than fulvestrant alone, resulting in an ICER of $152,678 per QALY gained. The monthly cost of capivasertib ($5,141) had the largest impact on the ICER. At a WTP of $150,000, the probability that capivasertib + fulvestrant was cost-effective was 41%. To reach a 90% probability, the monthly cost of capivasertib must decrease to $4,576 (89% of the current price) at the same WTP threshold.

CONCLUSIONS: The combination of capivasertib + fulvestrant was not cost-effective compared to fulvestrant monotherapy for HR+/HER2- ABC/MBC patients at a $150,000 WTP threshold with a monthly cost of capivasertib at $5,141. The aforementioned analyses will also be performed in the PI3K/AKT/PTEN pathway-altered subgroup.