Proton pump inhibitors decrease efficacy of palbociclib in patients with metastatic breast

ObjectivesThe objective of this investigation was to assess the impact of concurrent proton pump inhibitors (PPIs) on progression-free survival (PFS) in patients with hormone receptor-positive and HER2-negative metastatic breast cancer (mBC) who received palbociclib as first-line or successives therapy.Materials and MethodsA retrospective observational study was conducted, enrolling patients diagnosed with estrogen receptor-positive, human epidermal growth factor receptor 2-negative mBC, and eligible for palbociclib treatment. Patients were categorized as "concurrent PPIs" if they received PPIs for at least two-thirds of the palbociclib therapy duration, and as "no concurrent PPIs" if they did not receive PPIs during the course of palbociclib treatment.ResultsA total of 165 patients were included in the study. Among first-line patients treated with palbociclib, those using concurrent PPIs exhibited a PFS of 8.88 months, while patients using palbociclib without concurrent PPIs had a PFS of 67.81 months (p < 0.0001). In second-line or subsequent treatments, patients on palbociclib with concurrent PPIs had a PFS of 7.46 months, whereas those using palbociclib without concurrent PPIs had a PFS of 17.29 months (p = 0.122).ConclusionThis study demonstrates that the concurrent use of PPIs in mBC patients receiving palbociclib negatively affects PFS, particularly in the first-line setting. Nevertheless, further investigation is warranted to explore the impact of PPIs on cycle-dependent kinase 4/6 inhibitors.