Title: Association of MammaPrint index and 3-year outcome of patients in the FLEX Registry trial with HR+HER2- early-stage breast cancer treated with chemotherapy with or without anthracycline

Publication: ASCO 2024, Abstract #511, Rapid Oral Abstract – Breast Cancer – Local/Regional/Adjuvant 5/31/24

Authors: Joyce O’Shaughnessy, Cathy Lynne Graham, Pat Whitworth, Peter D. Beitsch, Cynthia R. C. Osborne, Rakhshanda Layeequr Rahman, Eric Allen Brown, Linsey P. Gold, Nathalie McDowell Johnson, Adam Brufsky, Harshini Ramaswamy, Nicole Stivers, Andrea Menicucci, William Audeh, FLEX Investigators’ Group

Background: The MammaPrint (MP) risk of distant recurrence signature identifies hormone receptor-positive (HR+), HER2-negative early-stage breast cancer (EBC) patients (pts) with increased or decreased chemosensitivity and chemotherapy (CT) benefit. The MINDACT trial demonstrated excellent outcomes for MP Low Risk tumors without CT, and previous studies show MP High Risk tumors exhibit higher sensitivity and benefit with CT. There remains an unmet clinical need for identifying biomarkers to inform specific regimen planning for pts who qualify for CT. Here, the association of MP index and 3-year (yr) Recurrence-Free Interval (RFI) was evaluated in pts with HR+HER2-, genomically High Risk Luminal B-Type EBC treated with taxane and cyclophosphamide (TC) vs anthracycline + TC (AC-T).