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). Here, ESR1 is linked to breast cancer.