The study design was men and postmenopausal women with advanced/metastatic, ER-positive, HER2-negative breast cancer, who have progressed on or after 1 or 2 lines of endocrine therapy for advanced disease, one of which was administered in combination with CDK4/6i, ≤ 1 line of chemotherapy for advanced disease ECOG performance status (PS) 0 or 1. The gene discussed is CDK4; the disease is breast cancer.