Objective

Ribociclib plus fulvestrant combination therapy recently gained FDA approval to treat postmenopausal women with HR+/HER2- breast cancer. This study aimed to determine the cost-effectiveness of ribociclib plus fulvestrant versus placebo plus fulvestrant therapy in the target population from a US payer perspective.

Methods

A Partitioned survival analysis model composed of three health states (progression-free, progressed disease and death) was constructed to evaluate the cost-effectiveness of ribociclib plus fulvestrant vs placebo plus fulvestrant. The progression-free survival and the overall survival data points were extracted from published Kaplan-Meier curves in the MONALEESA-3 study and fitted to parametric curves. The safety and efficacy of the treatment was referenced from the MONALEESA-3 trial. Costs were obtained from standard sources, including the Red Book for medication, Medicare Clinical Laboratory/Physician Fee Schedule for clinical utilization, and the literature for costs of managing adverse events, subsequent therapy, and end-of-life care. Utilities and disutility values were obtained from literature to calculate quality-adjusted life years (QALYs). One-way and probabilistic sensitivity analyses were conducted to test the model robustness. Several scenario analyses were also investigated.

Results

In the base case, the ribociclib arm was associated with $522,844 and 3.25 QALYs compared to $50,395 and 2.14 QALYs in the placebo arm, leading to an incremental cost-effectiveness ratio (ICER) of $425,951/QALY. The cost of ribociclib had the biggest impact on the model and constituted 89% of the total cost for the ribociclib arm. The probabilistic sensitivity analysis projected that the ribociclib plus fulvestrant treatment would have a net benefit over the fulvestrant only therapy at a WTP of $405,600/QALY.

Conclusion

At a willingness-to-pay (WTP) threshold of $150,000/QALY, the addition of ribociclib to fulvestrant is not considered to be cost-effective in postmenopausal women with HR+/HER2-, advanced breast cancer.