Abstract P4-01-30: Real-world treatment patterns and survival among adults with metastatic breast cancer with BRCA1/2 mutations

Abstract Background: Limited information is available about real-world treatment patterns and survival among patients with metastatic breast cancer (mBC) with BRCA1/2 mutations. BRCA1/2 mutations, which are involved in the repair of DNA double-strand breaks, are rare. Since 2018, PARP inhibitors (olaparib and talazoparib) have been approved for the treatment of patients with germline BRCA-mutated HER2-negative locally advanced and/or mBC. Methods: This retrospective chart review study included adults diagnosed with mBC with ≥1 oncogenic somatic BRCA1/2 mutation detected by tumor comprehensive genomic profiling who began a line of therapy on or after July 1, 2014, at 3 oncology centers in the American Association for Cancer Research (AACR) Project Genomics Evidence Neoplasia Information Exchange (GENIE) consortium. The index date was the first initiation of a new therapy for mBC in this period (which could be first-line [1L] or subsequent line of therapy). Data on all available lines of therapy post-index were collected. Treatments received in different lines of therapy for mBC and overall survival (OS) were described separately for patients with HR-positive/HER2-negative (HR+/HER2-) mBC, triple negative mBC (TNBC), and HER2-positive (HER2+) mBC. OS from the start of each line of therapy was assessed using Kaplan-Meier analysis. Results: A total of 48 women with mBC met the inclusion criteria. The mean age at index was 58 years; 73% of women were White. Common sites of metastases included lymph nodes (56%), bone (52%), and lungs (31%). Somatic BRCA1 mutation was detected in 48% and BRCA2 mutation was detected in 54% of women. Assessment of germline BRCA mutations was conducted in 25 (52%) women; 2 (8%) of assessed women tested positive for germline BRCA mutations. 29 (60%) of women had HR+/HER2- mBC, 9 (19%) had TNBC, 9 (19%) had HER2+ mBC, and 1 woman had unknown HER2 status. Treatments received in different lines of therapy for mBC and OS from start of each line of therapy by HR and HER2 status are reported in Table 1. Common treatments for women with HR+/HER2- mBC included endocrine-based therapy, and chemotherapy. Women with TNBC were most often treated with chemotherapy. Women with HER2+ mBC most often received endocrine-based therapy in 1L; chemotherapy or HER2-targeted combination therapy in second-line (2L); and chemotherapy or HER2-targeted monotherapy in third-line (3L). Median OS from the start of 1L therapy was 37.5 months among women with HR+/HER2- disease; 20.0 months for women with TNBC; and 51.7 months for women with HER2+ disease. Conclusions: These findings provide real-world insights about treatment patterns and survival among women with mBC and BRCA1/2 mutations. Further studies with larger sample sizes are needed to confirm these findings. Table 1. Treatment patterns and survival by line of therapy, HR, and HER2 status among patients with BRCA1/2 mutated mBC Citation Format: Priyanka Bobbili, Jasmina Ivanova, David B. Solit, Niharika Mettu, Shannon McCall, Mallika Dhawan, Maral DerSarkissian, Bhakti Arondekar, Jane Chang, Alexander Niyazov, Jocelyn Lee, Risha J. Huq, Michelle Green, Michelle Turski, Aruna Muthukumar, Mianzhao Guo, Mei Sheng Duh, William Oh. Real-world treatment patterns and survival among adults with metastatic breast cancer with BRCA1/2 mutations [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 P4-01-30.