Clinical outcomes and safety of zoledronic acid in castration-resistant metastatic prostate cancer with bone metastases: real-world data from Côte d’Ivoire

Background Zoledronic acid is used to prevent skeletal complications in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases. Real world data on its use in resource-limited setting, particularly in sub-saharan Africa, remain scarce. Aim To describe clinical outcomes, skeletal-related events, safety and quality of life in patients with metastatic castration-resistant prostate cancer (mCRPC) and bone metastases treated with zoledronic acid in Côte d’Ivoire. Methods We conducted a retrospective, single center cohort study including 144 patients with mCRPC and bone metastases treated with zoledronic acid at Treichville university Hospital between January 2019 and December 2021. The primary endpoint was skeletal event-free survival (SEFS) defined as the time from the first zoledronic acid administration to the first on-treatment skeletal related event (SRE). Patients without an SRE were censored at their last available follow-up. Results The median age was 67 years (range: 42–91), and 133 patients (92.4%) were older than 50 years. Before zoledronic acid initiation, 59 patients (41.0%) had experienced at least one skeletal-related event. After treatment initiation, 30 patients (20.8%) experienced at least one new on-treatment SRE, whereas 114 (79.2%) did not. Among patients who experienced an SRE, the median time to the first event was 9 months (range 5-11). Median SEFS was not reached and the estimated 12-month SEFS was 79.2%. The most frequently documented adverse events were bone pain (18.8%), constipation (18.1%) and nausea (9.7%). FACT-G data at both baseline and 12-month were available for 129 patients (89.6%) and mean scores across all four FACT-G domains, as well as the total FACT-G score, were numerically lower at 12 months than at baseline. Conclusion In this retrospective cohort of patients with mCRPC and bone metastases, 20.8% experienced a new SRE after zoledronic acid initiation, while median SEFS was not reached. FACT-G scores decreased during follow-up. These findings provide real-world data on zoledronic acid use in a resource-limited setting.