Patients with metastatic HER2-low breast cancer (defined as IHC 1+ or IHC 2+/ISH-negative) who are hormone receptor-positive, have previously received cyclin-dependent kinase 4/6 (CDK4/6) inhibitors and at least one line of chemotherapy (or who experienced disease progression within six months after [neo] adjuvant chemotherapy), and are considered refractory to endocrine therapy, should be considered candidates for treatment with T-DXd (expert-adapted recommendation). This evidence concerns the gene ERBB2 and breast cancer.