Is adding ribociclib to fulvestrant cost-effective in treating postmenopausal women with HR+/HER2-advanced or metastatic breast cancer? A US payer perspective cost utility analysis

BACKGROUND: Breast cancer is the most prevalent type of cancer in women in the United States. Ribociclib plus fulvestrant combination therapy gained US Food and Drug Administration approval to treat postmenopausal women with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/ HER2-) advanced or metastatic breast cancer in 2018. OBJECTIVE: To determine the cost-effective-ness of ribociclib plus fulvestrant vs placebo plus fulvestrant therapy in the target popula-tion from a US payer perspective. METHODS: A partitioned survival analysis model composed of 3 health states (progres-sion free, progressed disease, and death) was constructed to evaluate the cost-effective-ness of ribociclib plus fulvestrant vs placebo plus fulvestrant. The progression-free sur-vival 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 costs, Medicare Clinical Laboratory/Physician Fee Schedule for clini-cal utilization, and the literature for costs of managing adverse events, subsequent therapy, and end-of-life care. Utility and disutility values were obtained from litera-ture 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 plus fulvestrant arm was associated with $522,844 and 3.25 QALYs compared with $50,395 and 2.14 QALYs in the placebo plus fulvestrant arm, leading to an incremental cost-effec-tiveness ratio of $425,951/QALY. The cost of ribociclib had the biggest impact on the model and constituted 84% of the total cost for the ribociclib plus fulvestrant arm. The probabilistic sensitiv-ity analysis projected that the ribociclib plus fulvestrant treatment would have a net benefit over the placebo plus fulvestrant therapy at a willingness-to-pay (WTP) threshold of $405,600/QALY. CONCLUSIONS: At a WTP threshold of $150,000/QALY, the addition of ribociclib to fulvestrant is not considered to be cost-effective in post-menopausal women with HR+/HER2-advanced or metastatic breast cancer. The findings send a strong price signal to the manufacturer and can be used to facilitate payers with price negotiation in making coverage decisions.