Abstract P5-11-11: A preliminary assessment of knowledge, attitudes, and awareness surrounding ESR1 mutations and biomarker testing amongst medical oncologists

Abstract

Abstract Background: Estrogen receptor gene (ESR1) mutations present in breast cancer patients are associated with resistance to endocrine therapy and worse patient outcomes. Recent findings suggest ESR1 mutations are present in up to 40% of metastatic breast cancer (mBC) patients' tumors. The objective of this study was to evaluate the perceptions of precision medicine and biomarker testing specific to ESR1 mutations among medical oncologists. Methods: Ten 60-minute web-assisted, telephone interviews were conducted with medical oncologists. Each physician was prescreened prior to being interviewed to ensure board certification and practice experience between 2 and 35 years. Each participant spent greater than 30% of their time on direct patient care and managed the treatment of more than 30 different cancer patients per month, with a minimum of 15 breast cancer patients, including at least five who had metastatic breast cancer and at least one patient with an ESR1 mutation. Results: A 10-20% prevalence of ESR1 mutation was estimated by the oncologists. However, the practitioners did accept the possibility of a 40% prevalence. Physician knowledge of ESR1 mutations included the relationship between ESR1 mutations and efficacy of endocrine therapies and its association with poorer outcomes. None of the medical oncologists interviewed were highly satisfied with the existing armamentarium of treatments for patients with an ESR1 mutation. In general, the interview participants were highly comfortable ordering ESR1 companion diagnostics to test for an ESR1 mutation, pending viable treatment options are available. Nonetheless, most physicians will wait until the patient has progression of disease before ordering a biomarker test. Several areas of unmet need in the mBC arena were offered by the survey participants, including more efficacious hormonal options for later-line therapies, better durability of remission, improved drug tolerability profiles, and lower treatment costs. Conclusion: Most oncologists acknowledged that personalized treatment is beneficial because it allows for better efficacy than a “one size fits all” approach. The study results also suggest that there are few barriers and drawbacks to the use of personalized medicine in the mBC arena, as most physicians expect precision medicine to account for the majority of advances in breast cancer treatments in the foreseeable future. Support: Sermonix Pharmaceuticals Citation Format: Goldfarb SB, Goetz MP, Plourde PP, Attias E, Portman DJ. A preliminary assessment of knowledge, attitudes, and awareness surrounding ESR1 mutations and biomarker testing amongst medical oncologists [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-11-11.