On 17 January 2025, based on the TROPION-Breast01 trial, the FDA approved Dato-DXd for adult patients with unresectable or metastatic, hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative (IHC 0, IHC1+ or IHC2+/ISH−) breast cancer who have received prior endocrine-based therapy and chemotherapy for unresectable or metastatic disease [63]. The gene discussed is ERBB2; the disease is breast cancer.