OBJECTIVES: To assess the cost-effectiveness of elacestrant compared to fulvestrant in second-line treatment for estrogen receptor-positive (ER+) and human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer from the US payer perspective.

METHODS: We developed a three-state partitioned survival model to estimate the cost-effectiveness of elacestrant compared to fulvestrant over a lifetime horizon in second-line treatment for ER+/HER2- advanced breast cancer. Elacestrant was dosed at 400 mg orally once daily, while fulvestrant was administered at 500 mg intramuscularly on Days 1, 15, 29, and then once monthly indefinitely or until disease progression. We fit parametric survival models to the published Kaplan Meier curves from of the EMERALD phase III randomized clinical trial. Final model selection was based on goodness of fit, visual inspection, and clinical plausibility. Costs, including drug costs, administration costs, and outpatient visit costs, were collected from the U.S. Department of Veteran Affairs (VA) Big 4 price, IBM^® Micromedex^® RED BOOK^®, and published literature. All costs were collected in U.S. dollars and were inflated to the year 2023. Health utilities were extracted from published literature. Both costs and utilities were discounted by 3%. To address model uncertainty, we conducted a one-way sensitivity analysis to test which parameters were the most influential.

RESULTS: Total costs for elacestrant in our model were $398,754, in contrast to $285,970 for fulvestrant. Total QALYs for elacestrant were 1.46, compared to 1.32 for fulvestrant. The incremental costs were $112,784, and incremental QALYs were 0.14. The base-case ICER was $811,309 per QALY gained. Sensitivity analysis highlights the substantial influence of survival curve parameters, progression-free utility, and elacestrant drug costs on the ICER.

CONCLUSIONS: At the willingness-to-pay threshold of $150,000 per QALY, elacestrant is not cost-effective as a second-line treatment for ER+/HER2- advanced breast cancer.