Abstract TF2-2: Heterogeneity in treatment outcomes for HER2+ breast cancer - Clinical management strategies

Abstract

Abstract HER2-positive breast cancers are complex tumors that are clinically and biologically heterogeneous. Even within HER2+ breast cancer, there are different molecular subtypes, mutational profiles, levels of HER2 protein, and immune infiltration. Additionally, HER2 may not be expressed homogeneously among all the cancer cells in the same tumor, some tumors may have low HER2 expression, while other tumors evolve during treatment. These molecular differences help explain why patients do not benefit to the same extent to HER2-directed therapies. We will review data regarding outcomes for tumors with known tumor heterogeneity, hormone receptor positivity, HER2-low positivity, and cases where brain metastases may be present. We will discuss optimal clinical management in the modern era with multiple HER2-directed therapies, including next-generation antibody-drug conjugates. Future strategies to tailor therapy to the individual patient will need to not just factor in anatomic tumor burden, but also key molecular features. Citation Format: S Tolaney. Heterogeneity in treatment outcomes for HER2+ breast cancer - Clinical management strategies [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr TF2-2.