Patient, Oncologist, and Payer Preferences for Adjuvant Endocrine Therapy and CDK4/6 Inhibitor Regimens in Early-Stage Breast Cancer: A Discrete Choice Experiment

Several adjuvant phase III trials are evaluating cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) in combination with endocrine therapy (ET) in hormonal receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) early-stage breast cancer (eBC). This study examines preferences for this combination regimen and ET alone among patients, oncologists, and payers in the United States. A web-based questionnaire, including a discrete choice experiment (DCE), was administered to patients, practicing oncologists, and payers. In the DCE, respondents selected between hypothetical treatment profiles with attributes associated with ET monotherapy and CDK4/6i + ET regimens. Each treatment alternative was defined by the following attributes: 5-year invasive disease-free survival (iDFS), nausea, diarrhea, neutropenia, alopecia, dosing schedule, and electrocardiogram (ECG) monitoring. Payers had the additional attribute of annual per-patient treatment cost. Hierarchical Bayesian models were used to estimate relative preference weights for each attribute-level and relative attribute importance. For patients (n=300) and oncologists (n=200), iDFS was most important (2 to 3 times more important than the next most important attribute), followed by neutropenia and diarrhea risks for patients and oncologists, respectively. Patients and oncologists required an improvement in iDFS of 8.0 and 5.6 percentage-points, respectively, to accept an increase in diarrhea risk from 11% to 81%. Payers (n=60) viewed annual per-patient cost as most important for treatment access decision-making, closely followed by iDFS. Payers required an improvement in iDFS of 21.8 percentage-points to accept an increase in cost from $5,100 to $149,400. Across all stakeholder groups, dosing schedule, alopecia risk, and ECG monitoring were perceived as least important. Patients, oncologists, and payers expect a large absolute risk reduction in efficacy to offset the potential risks and costs of adding a CDK4/6i to current standard of care. An open discussion between all stakeholders is necessary to ensure that decision-making, whether at patient- or system-level, is informed by preferences for novel treatments, like CDK4/6is.