Abstract PS5-02-13: Journeying Through the Spectrum of HER2 Expression Breast Cancer Clinic: Education Outcomes on Guiding Treatment Decisions

Abstract BACKGROUND: A significant change in practice has occurred in breast cancer based on an improved understanding of HER2 expression existing on a broader spectrum than previously known. Despite the availability of personalized treatments for patients with metastatic breast cancer (mBC) based on their HER2-expression status, many patients who express HER2 are not receiving the optimal, tailored treatment for their disease. This is largely due to a lack of clarity surrounding HER2 testing, integration of HER2-targeted therapies across all subtypes of breast cancer, and management of unique adverse events (AEs) associated with novel HER2-targeting therapies. An interactive, case clinic was designed for oncology clinicians to engage in applying the latest guideline-recommended treatment approaches for mBC to close these gaps and ensure patients receive optimal therapy. METHODS: The branched-learning curriculum was comprised of two 30-minute tracks evaluating best practices in the management of HER2-positive and HER2-low breast cancer. The education launched on Medlive.com in September 2024 and will remain available for 12 months. Following a pre-assessment, learners selected their initial preferred track, which included several concise and easy-to-digest modules framed by clinical cases. Faculty experts provided rationales for each decision-point option before moving on to the next module. Discussions ensued on factors influencing treatment selection, guidelines and clinical evidence, treatment-sequencing strategies, and strategies for adverse-event management. Pre-post assessment data through case decisions for HER2+ (track 1) vs HER2-low MBC (track 2)will be presented. Results: To date, more than 1,300 clinicians have engaged with the education program, 74% of whom were MD/DO and 81% designating their specialty as oncology. Given a choice of selecting tracks, 91% initiated the education in track 1 and 89% of all learners completed both tracks. An approximate 16% improvement was seen across all knowledge and competence questions for intended learners (pathology and oncology speciaties) with higher gains - upwards of 50% - demonstrated for confidence treating HER2-low MBC vs HER2+ MBC. The reported intended changes in clinical practice included: • Greater personalized treatment sequencing based on patient-specific characteristics (36%)​ • Higher frequency of use of novel HER2-targeted agents in 2nd-line therapy (29%)​ • Implementing stricter monitoring for AEs associated with HER2-targeted therapies (27%)​ • Rigorous testing for HER2-low expression in patients with MBC (25%)​ • Increasing referrals for clinical trials of novel HER2-targeted agents (20%) ​ Pre-test variability in responses indicated that some learners were unclear on when additional testing is warranted, likely due to inconsistent application of updated HER2 testing protocols in clinical practice. Conclusions: The post-test gains indicate an improved ability to differentiate between available ADCs, with greater recognition of novel therapies as the preferred next-line therapy in HER2-low disease due to its targeted mechanism against HER2, even at low levels. However, the persistent gap suggests an opportunity to reinforce how HER2 expression levels influence ADC selection and where other ADCs may fit into later-line treatment. Improvements were seen in testing protocols, treatment application, and AE management, for relevant populations likely to benefit. These outcomes demonstrated the impact of this education initiative focusing on point-of-care decisions. Support was provided by an independent educational grant from Daiichi Sankyo, Inc. and AstraZeneca Pharmaceuticals.​​ Citation Format: T. Ackbarali, K. Jones, A. Bardia, S. Hurvitz. Journeying Through the Spectrum of HER2 Expression Breast Cancer Clinic: Education Outcomes on Guiding Treatment Decisions [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS5-02-13.