Impact of HER2 ‐low expression on the efficacy of endocrine therapy with or without CDK4 /6 inhibitor in HR ‐positive/ HER2 ‐negative metastatic breast cancer: A prospective study

作者：Yun Wu, Hongnan Mo, Hangcheng Xu, Yan Wang, Jiayu Wang, Fei Ma, Binghe Xu · 发表于：Thoracic Cancer · 年份：2024 · DOI：10.1111/1759-7714.15282 · 被引用次数：8 · 研究领域：Advanced Breast Cancer Therapies、Breast Cancer Treatment Studies、HER2/EGFR in Cancer Research

BACKGROUND: CDK4/6 inhibitors in combination with traditional endocrine therapy (ET) have become the recommended first-line therapy for HR-positive/HER2-negative metastatic breast cancer (MBC). The aim of this prospective study was to evaluate the relationship between HER2-low expression and clinical outcomes in HR-positive/HER2-negative MBC patients receiving ET with or without CDK4/6 inhibitors. METHODS: Between April 2016 and November 2019, 233 women with HR-positive/HER2-negative MBC who received ET with or without CDK4/6 inhibitors were enrolled into the study. The primary endpoint was progression-free survival (PFS). Statistical analysis included descriptive statistics, Kaplan-Meier curves, and Cox proportional hazards models. RESULTS: HER2-low and HER2-zero subgroups in the CDK4/6 inhibitor plus ET cohort showed no significant difference in the median PFS (10.9 vs. 8.0 months; hazard ratio: 0.92; 95% confidence interval [CI]: 0.64-1. 30; p = 0.65), while HER2-low subgroup showed a significantly shorter median PFS compared to the HER2-zero subgroup in the ET alone cohort (5.6 vs. 17.0 months; hazard ratio: 2.82; 95% CI: 1.34-5.93; p = 0.0044). Moreover, the objective response rate was significantly lower in the HER2-low subgroup than the HER2-zero subgroup in the ET alone cohort (10.5% vs. 40.0%, p = 0.047). Lastly, no significant difference was observed in the overall survival between the HER2-low and HER2-zero subgroups in both cohorts. CONCLUSION: This study suggeste...