ERBB2 and breast carcinoma: CDK4/6 inhibitors combined with endocrine therapy (aromatase inhibitors or fulvestrant) represent the standard-of-care for HR+HER2- advanced breast cancer, demonstrating significant improvements in progression-free survival (PFS) and overall survival (OS) across first- and later-line settings (Wang et al., 2020; Howie et al., 2019).