Limited data is available assessing sequencing of antibody drug conjugates (ADCs) in patients with hormone receptor-positive (HR +), human epidermal growth factor 2 (HER2)-negative, HER2-low, and triple-negative metastatic breast cancer (MBC), including patients with brain metastases (BrM) or leptomeningeal disease (LMD). This evidence concerns the gene ERBB2 and Langer mesomelic dysplasia.