Cost-effectiveness analysis of abemaciclib and endocrine therapy combination for the adjuvant treatment of HR+/HER2-, node-positive, high-risk, early breast cancer

Abstract Background: Abemaciclib is the only approved cyclin-dependent kinase 4/6 (CDK4/6) inhibitor approved for adjuvant treatment of hormone receptor-positive, human epidermal growth factor receptor-2-negative (HR+/HER2-), node-positive, high-risk early breast cancer (EBC) patients. However, the addition of abemaciclib to the standard of care endocrine therapy (ET, such as tamoxifen or aromatase inhibitors) results in a drastic increase to the overall healthcare costs. Objective: In this study, we aimed to evaluate the cost-effectiveness of abemaciclib and ET combination versus ET monotherapy for the adjuvant treatment of HR+/HER2-, EBC from the U.S. third-party payer perspective. Methods: A Markov-based decision analytic model using TreeAge Software was developed. The model simulated lifetime costs and health outcomes over a lifetime. The model incorporated the disease course of the progression-free disease, progressive disease, death due to disease, and mortality due to other causes. All clinical data and utilities were derived from the literature and clinical trial: monarchE. Notable adverse events such as neutropenia, leucopenia, anemia, and diarrhea were included. Age-specific mortality risk was calculated from the U.S. life tables. The outcomes were measured by costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER). The willingness-to-pay threshold was set at $100,000 per QALY gained. Results: We simulated our analysis on patients assigned to either abemaciclib + ET or ET alone groups as per the monarchE trial. The median age of the patients was 51 years. In base case analysis, the total costs for abemaciclib plus ET and ET alone treatment, were USD 122,052.11 and USD 40,344.87, respectively. Abemaciclib plus ET treatment produced 4.5 QALYs, while the ET treatment alone produced 4.31 QALYs. Overall, abemaciclib plus ET was marginally more effective than ET with an additional 0.20 QALYs but much costlier with an ICER of $417,780.18/QALY. For utilities ranging from 0.41 to 0.69, the ICERs ranged from USD 36,5950 to USD 4,463,866.59 per QALY, which exceeded the WTP threshold. Using probabilistic sensitivity analysis, we estimated that the combination of abemaciclib plus ET was a cost-effective strategy at the willingness-to-pay threshold of $500,000 per QALY or higher for the base case population. Conclusion: At current costs, abemaciclib plus ET is not cost-effective as compared to ET monotherapy for patients with node-positive, high-risk, HR+/HER2- EBC in the US healthcare system from the third-party payer perspective. Citation Format: Ashna Talwar, Ashish Deshmukh, Meghana Trivedi, Rajender R. Aparasu. Cost-effectiveness analysis of abemaciclib and endocrine therapy combination for the adjuvant treatment of HR+/HER2-, node-positive, high-risk, early breast cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4364.