Clinical Outcomes, Treatment Patterns, and Health Resource Utilization Among Metastatic Breast Cancer Patients with Germline BRCA1/2 Mutation: AReal-World Retrospective Study.

Abstract

With evolving treatment guidelines for germline BRCA1/2 mutation (gBRCAm) in breast cancer, we present the latest gBRCA testing rates among metastatic breast cancer (mBC) patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) or triple-negative breast cancer (TNBC). Among these patients with gBRCAm, we analyzed clinical outcomes, treatment patterns, and health resource utilization (HRU). The Flatiron Health electronic health record database was used to assess gBRCA testing rates in a real-world retrospective analysis of US patients at least 18years old with HR+/HER2- or TNBC, and with mBC diagnosed from January 2011 to February 2018. Outcomes were compared between gBRCAm patients with HR+/HER2- vs TNBC, adjusting for imbalances utilizing inverse probability treatment weighting; effects of HR+/HER2- vs TNBC on overall survival (OS) were assessed, antineoplastic treatments summarized, and HRU analyzed using t tests. The study included 12,021 mBC patients (HR+/HER2-, 10,291; TNBC, 1730). Results for gBRCA testing were available for 2005 (16.7%) patients (HR+/HER2-, 1587; TNBC, 418). A total of 229 (1.9%) patients (HR+/HER2-, 165; TNBC, 64) had gBRCAm. Significantly worse OS in gBRCAm mBC was observed in TNBC vs HR+/HER2- [hazard ratio (95% confidence interval), 0.45 (0.27-0.74); p = 0.002]. Estimated median and 4-year OS rates for gBRCAm mBC patients with either HR+/HER2- or TNBC were 38.0months, 23.4months and 35.6%, 21.2% respectively. The most common first-line treatment post diagnosis for gBRCAm HR+/HER2- was letrozole (8%) vs capecitabine (14%) for gBRCAm TNBC. The number of HRU treatment visits per patient per year was significantly (p < 0.05) higher among gBRCAm mBC patients with TNBC vs HR+/HER2-. Among HER2- mBC patients, gBRCA testing rates are low. Among gBRCAm HER2- mBC patients, the poor OS and HRU burden observed, especially in patients with TNBC, demonstrate an unmet need for more efficacious, targeted, and less HRU-intensive treatment options. Pfizer.