Abstract 1541: Heterogeneity of the hormone receptor-positive breast tumor immune microenvironment according to patient’s body mass index

Abstract Background: Obesity is a risk factor for postmenopausal hormone receptor-positive (HR+) breast cancer (BC) and is associated with poorer outcomes. “Obesity-paradox”, a phenomenon where obesity (BMI ≥ 30) is associated with better outcomes in patients treated with immune checkpoint inhibitors (ICI), has been observed in several cancer types. It is however under-explored in BC, especially HR+ BC. Emerging data from recent trials (KEYNOTE-756 and CheckMate 7FL) have shown the potential benefits of ICI for treating early HR+ BC. This prompted the need for better insights into the biological link between obesity and HR+ BC, particularly its tumor immune microenvironment (TIME). Patients Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 1541.