A Retrospective Analysis of Denosumab for the Treatment of Bone Metastases in Chinese Patients With Breast Cancer

BACKGROUND: Denosumab entered the Chinese market for the first time in 2020. Since it is a short period of time, there is a lack of data on its effectiveness and safety in Chinese people. The objective of this study was to evaluate the effectiveness and safety of denosumab in delaying skeletal-related events (SREs) in patients with breast cancer metastatic to bone. METHODS: The study retrospectively analyzed data from breast cancer patients with bone metastases (BM) who were treated with denosumab in the First Affiliated Hospital of Nanjing Medical University from September 2020 to January 2022. The primary endpoint was SRE incidence at 1 year after receiving denosumab treatment. The secondary endpoints included time to first on-study SRE and safety. Descriptive analysis was utilized to display clinicopathological features. The Kaplan-Meier method was used to estimate the median time to first on-study SRE in total population and subgroups. Logistic regression analysis and χ(2) test were employed to determine the potential factors influencing the occurrence of SREs. RESULTS: Fifty breast cancer patients with BM were enrolled in our study, and 54.0% of the patients had 5 or more metastatic bone lesions. After a median follow-up of 17.00 months, 24% of the patients developed SREs at 1 year after receiving denosumab treatment, and the median time to first on-study SREs was not reached. Five or more metastatic bone lesions were an independent risk factor for SRE occurrence (odds ratio = 6.06, 95% CI: 1.09-33.54, P = .039). The adverse events (AEs) associated with denosumab mainly included hypocalcemia (68.0%), periodontitis (28.0%), and myalgia (14.0%). Only 3 cases of grade III/IV AEs were reported, and no serious AEs occurred. CONCLUSION: Denosumab was effective and well tolerated in Chinese breast cancer patients with BM.