This ambispective cohort study sponsored by RenJi Hospital aims to evaluate the survival outcomes, adverse events, and predictive biomarkers associated with CDK4/6 inhibitors in patients with hormone receptor-positive advanced breast cancer. The study is currently recruiting participants and is expected to provide valuable insights into the efficacy and safety of CDK4/6 inhibitors, which are a growing class of therapies in oncology. The findings could enhance the competitive positioning of CDK4/6 inhibitors in the market, particularly as the demand for targeted therapies in breast cancer continues to rise. Additionally, the study may inform future clinical development strategies and potential partnerships for further research in this therapeutic area.