Combination of Palbociclib and Endocrine Therapy in Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer With or Without Brain Metastases.

Objective: This real-world study aimed to investigate the efficacy and safety of palbociclib plus endocrine therapy in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer in the real world in a Chinese population.

Methods: The clinical data of consecutively enrolled patients from the Cancer Hospital Chinese Academy of Medical Sciences, Shenzhen Center, and the University of Hong Kong - Shenzhen Hospital were collected. Progression-free survival curves were generated using log-rank tests with the Kaplan-Meier method. Univariate and multivariate logistic regression analyses were performed to identify the factors affecting progression-free survival.

Results: In total, 118 patients were enrolled, including 6 patients with brain metastases. At the last follow-up date, the median progression-free survival was 16.8 months (95% confidence interval, 11.1-22.5), with the 6-month and 12-month progression-free survival rates of 77.1% and 57.6%, respectively. The disease control rate and the intracranial disease control rate were 82.2% and 50%, respectively. A longer progression-free survival was observed for patients with the following characteristics: treatment-naive; without hepatic metastasis; sensitive to previous endocrine therapy and harboring fewer metastatic sites. The multivariate logistic regression analysis demonstrated that treatment lines and exposure to palliative chemotherapy were independent influencing factors of progression-free survival.

Conclusions: Palbociclib plus endocrine therapy in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer was effective and well-tolerated, even in patients with brain metastases. More benefits were observed in frontline therapy, chemotherapy-naive, and endocrine therapy-sensitive patients with fewer metastatic sites.