451 Patient characteristics and treatment patterns by BRCA/ATM mutation status in ovarian cancer patients: an EHR analysis in the PRIOR-2 study

Introduction/Background* Previous studies have reported median progression-free survival (PFS) of 12-18 months in ovarian cancer (OC). Testing for BRCA1/2 or ATM gene mutations in OC can inform treatment choice. Data on the treatment experience of patients with OC by BRCA/ATM mutational status in the United States (US) is needed. Methodology We identified female adults, ≥18 years, with OC from Optum’s de-identified electronic health record (EHR) database (1/1/2017 – 6/30/2020; N=16.6M female lives). Index date was first diagnosis of OC. Patients were observed for 12-months pre-index to capture baseline demographic, clinical and prognostic characteristics. Treatment with platinum-taxane CT, PARPi, bevacizumab and transition rates through lines of therapy or death by BRCA/ATM mutational status was examined. Result(s)* Among 1,901 OC patients tested for BRCA/ATM gene mutation, 616 (32.4%) were positive, 682 (35.9%) were negative and 603 (31.7%) had unknown status. Mean (SD) age was 59.5 (10.9) and 62.2 (12.1) years for patients with BRCA/ATM mutation and no mutation. No meaningful differences by BRCA/ATM mutational status (yes vs no) were found in the proportion of patients with stage 3/4 cancer (52.1% vs 52.1%), visceral metastasis (35.9% vs 31.8%) or ascites (30.8% vs 30.2%), at presentation; or in 1L platinum-taxane CT initiation (55% at 6 months). PARPi use differed by BRCA/ATM status and increased over time (table 1). Conclusion* While there are few differences in characteristics between patients by BRCA/ATM status, PARPi use was higher in patients with BRCA/ATM mutation; patients with no BRCA/ATM mutation were more often treated with bevacizumab. There is need for further research to understand the role of BRCA/ATM status on treatment choice and outcomes.