Abstract 891: Cost-effectiveness of CDK4/6 inhibitors in the first-line treatment of HR+/HER2- metastatic breast cancer in postmenopausal women in the United States
Authors: Masurkar Prajakta P. , Damgacioglu Haluk , Deshmukh Ashish , Trivedi Meghana 
Published: July 2021

Abstract
BACKGROUND: Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors are changing the management of the patients with hormone receptor-positive/HER2-negative metastatic breast cancer (HR+/HER2- MBC). The addition of CDK4/6 inhibitors to endocrine therapy is more efficacious than endocrine therapy alone for HR+/HER2- MBC patients, but it is also more expensive. This cost-effectiveness analysis study was designed to evaluate the economic value of adding CDK4/6 inhibitors to letrozole, an aromatase inhibitor.
OBJECTIVE: We aimed to evaluate the cost-effectiveness of abemaciclib plus letrozole or ribociclib plus letrozole or palbociclib plus letrozole versus letrozole monotherapy in the first-line treatment of HR+/HER2− MBC in the United States.
METHODS: We constructed a Markov-based decision-analytic model using TreeAge Software LLC, Cambridge, MA. Our model simulates lifetime costs and health outcomes over a 40-year lifetime horizon from a third-party payer perspective. The model incorporated the clinical course of a progression-free or stable disease, progressed disease, death, Neutropenia as a major adverse effect, and cancer-specific mortality. All clinical and utilities data were derived from the literature and clinical trials, including PALOMA-2, MONALEESA-2, and MONARCH-3. For consistent comparison, only letrozole specific data was derived from MONARCH-3. Outcomes were measured by costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios (ICERs). Deterministic and probabilistic sensitivity analyses were performed to evaluate the robustness of the results against uncertainties in the model parameters.
RESULTS: In our base case, the total health care costs for Palbociclib, Ribociclib, and Abemaciclib plus letrozole were $680,596, $ 676,292, and $ 635,606, respectively while the cost of letrozole monotherapy was $162,378. Palbociclib plus letrozole and Ribociclib plus letrozole were dominated strategies by Abemaciclib plus letrozole. Higher QALYs was associated with Abemaciclib plus letrozole (6.91 QALYs vs 5.83 QALYs for letrozole). Compared to letrozole monotherapy, Abemaciclib plus letrozole resulted in ICER of $ 436,855 per QALY. At willingness-to-pay thresholds of $100,000 per QALY gained, none of the strategies was found to be cost-effective. Letrozole monotherapy was the optimal choice. The model was sensitive to certain parameters such as cost of Abemaciclib, and transition probability of stable to the progressed state for Abemaciclib and letrozole. Base case results were consistent with the findings from the Monte Carlo simulation.
CONCLUSIONS: Our study found that none of the CDK4/6 inhibitors were cost-effective. Because of the current cost of CDK4/6 inhibitors, letrozole monotherapy was found to be an optimal choice for the first-line treatment of HR+/HER2- MBC.
Citation Format: Prajakta P. Masurkar, Haluk Damgacioglu, Ashish Deshmukh, Meghana Trivedi. Cost-effectiveness of CDK4/6 inhibitors in the first-line treatment of HR+/HER2- metastatic breast cancer in postmenopausal women in the United States [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 891.