Abstract PO4-06-06: Clinical Implications of Body Mass Index (BMI) in BRCA-associated Advanced Breast Cancer Patients Treated With PARP (Poly ADP-Ribose Polymerase) Inhibitors

Abstract

Abstract Background: PARP inhibitors (PARPi) have demonstrated promising results in patients with advanced as well as early breast cancer carrying germline BRCA1/2 pathogenic variants (PV). Although there is increasing attention to the effect of BMI on the outcomes of cancer patients, there is limited data on its effect on BRCA-associated advanced breast cancer patients receiving PARPi therapy. In this report, we evaluate the effect of BMI on the outcomes of advanced breast cancer patients with a BRCA PV and who received PARPi therapy. Methods: Patients with BRCA 1/2 germline PVs who presented to the University of Texas MD Anderson Cancer Center Breast Medical Oncology clinics and were treated with PARPi between 2008-2022 as part of their treatment for metastatic or recurrent disease were included in the analysis. The patients were divided into four groups according to BMI level as follows: underweight (< 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥30 kg/m2). Descriptive statistics, the Kaplan-Meier method, the Cox proportional hazards regression model, and Fisher’s exact test were used to report patient characteristics and outcomes. Progression-free survival (PFS) was calculated from the start of the PARPi therapy to the time of progression or death. Overall survival (OS) was calculated from the start of the PARPi therapy to the time of death of any cause. Results: One hundred and seven patients were treated with PARPi. The median BMI was 25.9 kg/m2 (14.8-61.2). In patients who received ≥2 cycles of PARPi, the overall response rate was 100% in the underweight group (n=4, 3.8%), 65.8% in the normal weight group (n=43, 41%), 64% in the overweight group (n=30, 28.6%), and 58.3% in the obese group (n=28, 26.7%). The median PFS was 5.4 months, 9.2 months, 9 months, and 8.6 months in underweight, normal weight, overweight, and obese patients, respectively. While the obese patients had a better outcome in terms of PFS (p = 0.0288), there was no significant difference observed in OS between BMI groups. Conclusion: In this analysis, we showed that obese patients with BRCA-associated advanced breast cancer had a better PFS. Future studies analyzing body composition parameters in BRCA-associated breast cancer patients treated with PARPi therapy could shed more light on the impact of obesity on outcomes. Citation Format: Fatma Akkoc Mustafayev, Mark Munsell, Rachel Layman, Clinton Yam, Angelica Gutierrez Barrera, Banu Arun. Clinical Implications of Body Mass Index (BMI) in BRCA-associated Advanced Breast Cancer Patients Treated With PARP (Poly ADP-Ribose Polymerase) Inhibitors [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-06-06.