Abstract 5559: Exploratory analysis of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) PIK3CA mutated (mut) advanced breast cancer (aBC) treated with taselisib (TAS) and/or fulvestrant (FUL) reveals increased CCNE2 expression with poor outcome to placebo (PBO) + FUL but not TAS + FUL in SANDPIPER | Publicación