Despite several studies supporting the efficacy of PARP inhibitor therapy in breast cancers with BRCA germline pathogenic variants (PVs), a team of researchers led by Fatma Mustafayeb, MD, stated that population remains difficult to treat. In a poster featured at the ASCO 2023 Annual Meeting in Chicago, IL, the team presented real-world single-center outcomes from a cohort of patients with advanced breast cancer with BRCA PVs who received PARP inhibitors.
The study reported that overall response rate (ORR) and treatment outcomes were comparable with those reported in clinical trials. However, they found ORR improved in patients who were naïve to platinum-based chemotherapy and those who received PARP inhibitors as a first-line therapy.
Real-World PARP Inhibitor Therapy in Breast Cancer
The authors enrolled 107 patients with metastatic or recurrent breast cancer with BRCA 1/2 germline PVs who received PARP inhibitor therapy between 2008 and 2022 at the University of Texas MD Anderson Cancer Center Breast Medical Oncology clinics.
The cohort had a median age at diagnosis of 38 years (range: 23-73). Overall, 97 (90.7) patients had invasive ductal carcinoma, 42 (39.3%) had triple-negative breast cancer, and 19 (17.8%) had stage IV de novo metastatic breast cancer. Sixty-two (57.9%) patients received 1 or more lines of chemotherapy, including 24 (22.4%) who received platinum-based regimens, prior to undergoing PARP inhibitor therapy.
Among 91 patients eligible for clinical response evaluation, the ORR was 59.4% and the duration of response was 7 months (range, 2.1-96.2). Comparatively, in platinum-naïve patients, the ORR was 70.4% and the duration of response was 7.4 months (range, 2.1-96.2). In addition, the median progression-free survival was 8.9 months (95% CI, 6.3-10.3) and the median overall survival was 25.8 months (95% CI, 18.3-30.9).
The authors suggested that “further studies of predictive markers of response and resistance as well as sequencing with platinums are needed to optimize the use of PARPi in this patient population.”
More highlights from the ASCO 2023 Annual Meeting