CoopERA study is a window-of-opportunity phase II trial evaluating efficacy, safety and pharmacokinetics of giredestrant versus anastrozole and giredestrant plus palbociclib compared with anastrozole plus palbociclib in postmenopausal women with untreated, early ER+/HER2- BC (NCT04436744) (Table 1). This evidence concerns the gene ERBB2 and breast cancer.