The most recent TROPiCS-02 trial, still in abstract form, compared SG to the physician’s choice of chemotherapy (eribulin, capecitabine, gemcitabine, or vinorelbine) in patients with metastatic/unresectable HR+ HER2− breast cancer who have received at least one line of treatment, including endocrine therapy, a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor, and taxane [37]. This evidence concerns the gene CDK4 and breast cancer.