ERBB2 and breast cancer: In a phase III trial (NCT01958021), ribociclib (600 mg/day; 1–21 days of a 28-day cycle) in combination with letrozole (2.5 mg/day, continuous treatment) significantly prolonged progression-free survival in postmenopausal women with HR + and HER2 − breast cancers compared with placebo plus letrozole (25.3 months vs. 16.0 months) treated patients [78].