Abstract P4-07-09: Identifying Drivers of First-Line HR+/HER2- Metastatic Breast Cancer Treatment Choices

Abstract Background: Despite demonstrated clinical benefits of first line (1L) cyclin-dependent kinases 4/6 inhibitors (CDK4/6i) and their preferred status in the NCCN guidelines, many appropriate patients with hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (mBC) in the United States (US) may still receive chemotherapy or endocrine monotherapy. US oncologists may consider treatment expectations, patient clinical characteristics, and non-clinical factors (e.g., cost, anticipated adherence) when selecting 1L mBC treatment regimens. However, little is known about how prevalent these decision factors are among US oncologists. Comprehensively understanding the decision-making process in 1L treatment selection is a critical step towards ensuring equitable care for patients with HR+/HER2- mBC. Objective: To describe self-reported clinical and non-clinical factors considered by US oncologists in selection of 1L treatment for HR+/HER2- mBC. Methods: Data were collected through from an anonymous cross-sectional online survey from a convenience sample of US oncologists from August-October 2021. Eligible oncologists were board certified, in practice 2-30 years, ≥50% of time spent in direct patient care, and managed ≥5 1L patients with HR+/HER2- mBC in past 3 months. Respondents were sampled from a national research database of physicians sourced from multiple databases (e.g., American Medical Association Physician Masterfile). The survey captured self-reported demographic and practice characteristics and reported importance of the following factors in selecting 1L treatment for patients with HR+/HER2-mBC: anticipated treatment efficacy and safety, patient demographics, and clinical and non-clinical characteristics. Study variables were summarized via descriptive statistics. Correlation analyses evaluated associations between patient demographics, clinical characteristics, treatment expectations, and non-clinical characteristics and oncologists’ self-reported 1L prescribing rates of CDK4/6i, aromatase inhibitor (AI) monotherapy, and chemotherapy. Results: 250 oncologists participated; 67% from community practice and the remainder from academic institutions (Table 1). Anticipated treatment efficacy and safety/tolerability were ranked as the most important factor considered by oncologists when selecting 1L treatments. 1L CDK4/6i prescribing was most strongly correlated with patient Medicare eligibility (r, 0.54, p< 0.05) and postmenopausal status (r, 0.67, p< 0.05). 1L chemotherapy prescribing was most strongly correlated with patient premenopausal status (r, 0.42, p< 0.05) and perimenopausal status (r, 0.31, p< 0.05), and physician consideration for patient symptom burden (r, 0.31, p< 0.05). 1L AI monotherapy prescribing was most strongly correlated with concerns with expected patient compliance to treatment (r, 0.42, p< 0.05) and patient cost/logistical challenges (r, 0.41, p< 0.05). Conclusion: This study found a variety of patient, clinical, and non-clinical factors may underlie US oncologists’ selection of 1L treatment for HR+/HER2- mBC. Anticipated efficacy and safety/tolerability were reported as the most important factors in 1L treatment decisions. Patient demographics, clinical characteristics, and considerations for cost and compliance challenges varied in association with 1L CDK4/6i, chemotherapy, and AI monotherapy prescribing patterns among US oncologists. Table 1. Oncologist Demographic and Practice Characteristics Citation Format: Adam M. Brufsky, Martine C. Maculaitis, Lewis Kopenhafer, Patrick Olsen, Ashley S. Cha, Lillian Shahied Arruda, Wendy Heck, Samantha K. Kurosky. Identifying Drivers of First-Line HR+/HER2- Metastatic Breast Cancer Treatment Choices [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-07-09.