A Phase III Randomized, Open-Label Study Evaluating Efficacy and Safety of Giredestrant Compared With Fulvestrant, Both Combined With a CDK4/6 Inhibitor, in Patients With Estrogen Receptor-Positive, HER2-Negative Advanced Breast Cancer With Resistance to Prior Adjuvant Endocrine Therapy (pionERA Breast Cancer)

The purpose of this study is to compare the effects, good or bad, of two hormonal treatments, giredestrant and fulvestrant, both given in combination with your study doctor’s choice of a class of medicines called CDK4/6 inhibitors, in people with ER-positive, HER2-negative advanced breast cancer that is resistant to adjuvant hormone therapy