Palbociclib Is Safe for Breast Cancer Patients With Mild Hepatic Impairment: A Multicenter Retrospective Study Using Real‐World Data

The liver is crucial for metabolizing the anticancer drug palbociclib, but limited information is available on the impact of hepatic impairment on its toxicity and efficacy, with no real‐world data available. This study aims to evaluate how hepatic impairment affects hematological toxicity and progression‐free survival (PFS) of palbociclib in advanced hormone receptor‐positive/human epidermal growth factor receptor 2‐negative breast cancer, using the National Cancer Institute scoring system, in a large real‐world dataset. This multicenter retrospective observational study included female patients treated with palbociclib between August 2017 and February 2024. Regression analysis was used to compare the risk of developing grade 3/4 hematological toxicity and PFS between patients with normal and mild impaired liver function. In total, 478 female patients were included. Patients with mild hepatic impairment ( n = 205) did not have an increased risk of developing grade 3/4 neutropenia compared with patients with normal hepatic function ( n = 273) (hazard ratio (HR) = 1.11; 95% CI 0.83–1.47). In addition, the PFS was not significantly different between both groups (HR = 1.15; 95% CI 0.93–1.42). In real‐world settings, patients with mild hepatic impairment do not have a higher risk of developing palbociclib‐induced neutropenia or disease progression than patients with normal hepatic function. These findings can guide clinicians when treating breast cancer patients with mild hepatic impairment.