ERBB2 and aneurysmal bone cyst: In the case of patients with HER2-negative luminal ABC, even those treated with multiple lines of systemic therapy, attention must be paid to possible variations in clinical management arising from the latest clinical trial results involving antibody–drug conjugates (ADCs), e.g., sacituzumab govitecan, trastuzumab deruxtecan, or datopotamab deruxtecan.