Xu, Xiaoqing

PURPOSE Testing for germline BRCA1 and/or BRCA2 mutations (gBRCAm) is recommended for patients with human epidermal growth factor receptor 2–negative (HER2–) breast cancer (BC) to guide treatment selection with poly (ADP-ribose) polymerase inhibitors (PARPis). However, real-world data on germline BRCA1 and/or BRCA2 (gBRCA) testing and PARPi treatment patterns in metastatic BC (mBC) are limited. METHODS Deidentified patient data from adults diagnosed with HER2– mBC between 2014 and 2022 were captured from electronic health records in the US Flatiron Health database. gBRCA testing patterns and prevalence were examined by tumor subtype (hormone receptor–positive [HR+]/triple-negative) and disease stage at diagnosis. Demographic and clinical characteristics were described by receipt of gBRCA testing and PARPi. PARPi treatment patterns were assessed, and real-word overall survival (OS) was estimated in patients with gBRCAm diagnosed with mBC after January 1, 2018. RESULTS Of the 15,006 total patients, 4,654 (31.0%) received a gBRCA test. gBRCA testing rates mostly increased from 2014 to 2022 and were lower in patients with HR+ than triple-negative tumors. Of the patients who underwent gBRCA testing, 337 (7.2%) had gBRCAm. From 2018 to 2022, PARPi was initiated in 94 (45.6%) of 206 patients with gBRCAm. With a median follow-up of 22.8 months across patients with available first-line treatment start dates, real-world OS was numerically longer among 94 patients with gBRCAm who received PARPi (32.3 months [95% CI, 22.7 to 47.4]) than among 99 patients who did not (21.9 months [95% CI, 18.4 to not reached]). CONCLUSION Although gBRCA testing increased over time, testing and PARPi utilization rates remained suboptimal in potentially eligible patients with HER2– mBC. Exploratory analysis showed numerically longer OS in patients who received PARPi. Wider and timelier gBRCA testing is warranted to inform potentially optimal treatment decisions.

e12502 Background: In March 2022, the United States Food and Drug Administration approved olaparib as adjuvant treatment (tx) for patients with germline BRCA1/2 pathogenic or likely pathogenic variants and HER2-negative eBC at high risk of recurrence who have been treated with neo-adjuvant or adjuvant chemotherapy. Approval was based on results from the OlympiA trial which demonstrated a significant increase in invasive-disease free survival [hazard ratio, 0.58; 99.5% CI, 0.41 to 0.82; P<0.001] and overall survival [hazard ratio, 0.68; 99% CI, 0.47-0.97; P=0.009] with olaparib vs placebo. To date, there has been limited real-world data for eBC on olaparib utilization patterns and characteristics of olaparib users. Methods: This retrospective analysis using closed claims from KHM included adult pts with HER2-negative eBC receiving first olaparib prescription (index date) from March 11, 2022 to Nov 30, 2023. Continuous medical and pharmacy enrollment of ≥12 months pre-index and ≥30 days post-index was required. Pt characteristics were summarized descriptively, and Kaplan-Meier (KM) analysis was conducted for time-to-event utilization outcomes. Outcomes were evaluated for pts overall and stratified by hormone receptor (HR) status and race/ethnicity. Non-persistence was defined as minimum of 2 consecutive missed prescription fills. Medication possession ratio (MPR) was calculated as the sum of days of olaparib supply, divided by the total number of days from olaparib initiation to the last claim plus days of olaparib supply in the last claim. Results: We identified 176 pts with HER2-negative eBC who received olaparib. Median age was 44 years, and the majority (66.5%) had commercial insurance. KM-calculated median persistence on olaparib was 11 months (95% CI: 9.2-12.2); overall, adherence measured by MPR ≥80% was 74.2% by month 6 of olaparib use; adherence is higher among Caucasian than non-Caucasian pts (Table). While the majority of HR+/HER2- pts (77.9%, N=53/68) took olaparib concurrently with other (88.7% hormonal) adjuvant tx, most TNBC pts (70.4%, N=76/108) received olaparib alone. Among TNBC pts who took olaparib concurrently with other adjuvant tx (N=32/108), 81.3% received olaparib combined with immunotherapy. Conclusions: Our study provides evidence of favorable persistence and adherence to adjuvant olaparib in a real-world setting and data on utilization of olaparib concurrently with other tx. Recent approvals of other adjuvant tx for HER2- high-risk eBC warrants further research on the efficacy of olaparib used alone, versus olaparib combined or sequenced with other treatments. Olaparib MPR ≥80% by follow-up time points between Caucasians and non-Caucasians. Cohorts 30 days 60 days 180 days 365 days Caucasians (N=70) 92.5% 71.7% 80.6% 90.9% Non-Caucasians(N=55) 88.7% 66.7% 70.0% 50.0%