biostudies-literatureUnknown15(1)Graziosi A<h4>Background</h4>Breast cancer is the fourth leading cause of cancer mortality worldwide. New drugs, such as cyclin-dependent kinase 4/6 inhibitors (CDKIs), increase the life expectancy of receptor-positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) breast cancer patients. This class acts to limit the G1/S transition in tumor cells, inducing tumor cell death. Owing to the basic nature of CDKIs, their solubilities are pH dependent and could be influenced by the concurrent use of acid-reducing agents such as proton pump inhibitors (PPIs). This meta-analysis aims to assess the impact of co-administering PPIs on the pharmacokinetics and clinical efficacy of CDKIs in breast cancer patients.<h4>Methods</h4>Four databases with English-language restriction were searched Systematic reviews36https://www.ebi.ac.uk/biostudies/studies/S-EPMC12859863biostudies-literaturePharmacokinetic interactions and clinical implications of PPIs and CDKIs in breast cancer: a systematic review and meta-analysis.PMC12859863Graziosi APani AFornasari DNani ASchianchi ADel Re MPane RBasso MMelis MGiossi RDanesi RAvantaggiato MTinazzo ECanella MfalsePharmacokinetic interactions and clinical implications of PPIs and CDKIs in breast cancer: a systematic review and meta-analysis.<h4>Background</h4>Breast cancer is the fourth leading cause of cancer mortality worldwide. New drugs, such as cyclin-dependent kinase 4/6 inhibitors (CDKIs), increase the life expectancy of receptor-positive (HR+) and human epidermal growth factor receptor 2 negative (HER2-) breast cancer patients. This class acts to limit the G1/S transition in tumor cells, inducing tumor cell death. Owing to the basic nature of CDKIs, their solubilities are pH dependent and could be influenced by the concurrent use of acid-reducing agents such as proton pump inhibitors (PPIs). This meta-analysis aims to assess the impact of co-administering PPIs on the pharmacokinetics and clinical efficacy of CDKIs in breast cancer patients.<h4>Methods</h4>Four databases with English-language restriction were searched 2025-01-01T00:00:00Z2025 Dec2026-06-11T05:32:17.616Z2026-06-11T03:08:30.303ZS-EPMC128598634146235210.1186/s13643-025-03046-0