97P Genomic bases of endocrine sensitivity in triple-positive early breast cancer: A translational analysis of the PerELISA trial

HER2 positivity is a driver of endocrine resistance in hormone receptor-positive (HR+) breast cancer (BC). However, clinical data suggests the existence of a subset of HR+/HER2+ BC that might be endocrine sensitive with a natural history similar to HR+/HER2-, especially when HER2 signaling is blocked. Given the scarcity of data on genomic bases of endocrine sensitivity in HR+/HER2+ BC, we planned this gene expression analysis in the context of the PerELISA trial. Our aim is to characterize genomic features associated with endocrine sensitivity in HR+/HER2+ BC.