RT Journal Article T1 Advances in CDK4 and 6 Inhibitors: Transforming Breast Cancer Treatment. A1 Santander Ballestín, Sonia A1 Abadía Labena, María A1 Avedillo-Salas, Ana A1 Marco Continente, Cristina A1 Arribas Blázquez, Marina A1 Luesma Bartolomé, María José AB Background and Objectives: Breast cancer is the most common malignant neoplasm worldwide and the most prevalent one among women. It represents the leading cause of cancer-related death among females. Cyclin-dependent kinase 4 and 6 inhibitors disrupt the cell cycle, inducing cellular senescence and, ultimately, apoptosis. Consequently, they have become a novel type of adjuvant therapy for the treatment of advanced or metastatic breast cancer characterised by positive hormone receptors and human epidermal growth factor receptor 2 (HER-2) negative.Methods: A systematic review was conducted, analysing the available literature on cyclin-dependent kinase 4 and 6 inhibitors published over the last five years. The aim was to evaluate the efficacy and safety of adding these drugs to the standard endocrine therapy for this pathology.Results: The combination of cyclin-dependent kinase 4 and 6 inhibitors with endocrine therapy was shown to improve progression-free survival, overall survival, and chemotherapy-free intervals in patients who received this combination therapy.Conclusions: The addition of CDK4/6 inhibitors to endocrine therapy in the treatment of advanced or metastatic breast cancer with positive hormone receptors and HER-2 negative significantly improved PFS, median survival, and chemotherapy-free intervals compared with the use of hormonal treatments alone or in combination with a placebo. Currently, CDK4/6 inhibitors are becoming established as a new standard treatment for this pathology, offering lower toxicity than chemotherapy. However, it is necessary to deeply investigate the mechanisms of treatment resistance and develop effective therapies to overcome them. AB Simple Summary:Breast cancer is the most common malignant neoplasm worldwide and the most prevalent one among women. Cyclin-dependent kinase 4 and 6 inhibitors have become a novel form of adjuvant therapy for the treatment of advanced or metastatic breast cancer characterised by positive hormone receptors and human epidermal growth factor receptor 2 (HER-2) negative. These inhibitors are considered a new standard treatment for this pathology, offering lower toxicity than chemotherapy. PB MDPI SN 2072-6694 YR 2025 FD 2025-02-24 LK https://hdl.handle.net/20.500.14352/118832 UL https://hdl.handle.net/20.500.14352/118832 LA eng NO Santander Ballestín, S.; Abadía Labena, M.; Avedillo-Salas, A.; Marco Continente, C.; Arribas Blázquez, M.; Luesma Bartolomé, M.J. Advances in CDK4 and 6 Inhibitors: Transforming Breast Cancer Treatment. Cancers 2025, 17, 760. https://doi.org/10.3390/cancers17050760 NO Author Contributions:Conceptualisation, S.S.B. and A.A.-S.; methodology, M.A.L.; investigation, M.A.L., S.S.B. and A.A.-S.; writing—original draft preparation, M.A.L., S.S.B. and A.A.-S.; writing—review and editing, S.S.B., C.M.C., M.J.L.B. and M.A.B. visualisation, S.S.B., C.M.C., M.J.L.B. and M.A.B.; supervision, S.S.B., A.A.-S. and M.J.L.B. All authors have read and agreed to the published version of the manuscript. DS Docta Complutense RD 12 abr 2025