Concomitant Use of Proton Pump Inhibitors and CDK4/6 Inhibitors in Metastatic Hormone-Positive Breast Cancer: A Real-World Cohort Study.

Introduction: Conflicting evidence exists regarding the concurrent use of cyclin-dependent kinase (CDK) 4/6 inhibitors and proton pump inhibitors (PPIs) in the treatment of breast cancer. This study aimed to investigate whether PPI use interferes with the efficacy of CDK4/6 inhibitors.

Methods: This retrospective, multicenter, real-world study included 205 patients with hormone receptor-positive, HER2-negative metastatic breast cancer.