In MONARCH 2, a global, double-blind, phase III study, 669 postmenopausal women with HR-positive/HER2-negative ABC progressing on or ≤12 months from their last endocrine therapy were randomly assigned 2:1 to receive abemaciclib or placebo (150 mg twice daily) on a continuous schedule and fulvestrant (500 mg, per label). The gene discussed is ERBB2; the disease is aneurysmal bone cyst.