In patients with HRpos/HER2neg breast cancer, the introduction of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors (Hortobagyi et al. 2016, 2022; Slamon et al. 2019, 2020; Slamon et al. 2018; Im et al. 2019; Tripathy et al. 2018; Sledge et al. 2017; Goetz et al. 2017; Finn et al. 2016; Turner et al. 2015; Nabieva and Fasching 2023; Engler et al. 2022; Schneeweiss et al. 2020), and as well trastuzumab deruxtecan (for HER2 low expressing tumors) (Modi et al. 2022) and sacituzumab govitecan (Rugo et al. 2023) have changed the treatment landscape in the advanced setting. The gene discussed is CDK4; the disease is breast carcinoma.