Improvement of renal function by changing the bone-modifying agent from zoledronic acid to denosumab

BACKGROUND: In order to help in selecting the optimum bone-modifying agent (BMA; zoledronic acid or denosumab), we investigated the impact of the BMA on the renal function of patients with bone metastases. MATERIALS AND METHODS: The present study consisted of 118 patients who were treated with denosumab for bone metastases secondary to prostate cancer, renal cell cancer, and urothelial cancer at our hospital between 2012 and 2015. The clinical course of the renal function of these patients, treated with zoledronic acid or denosumab, was retrospectively evaluated. RESULTS: Of the 118 patients who were treated with denosumab during the study period, 57 (48 %) had previously been administered zoledronic acid and 61 (52 %) had received denosumab as the first-line BMA. The reasons for changing from zoledronic acid to denosumab were increased creatinine serum level (26 patients, 46 %), patient preference (16 patients, 28 %), difficulty with venous infusion (10 patients, 17 %), and other reasons (5 patients, 9 %). The median level of creatinine clearance in the patients who changed from zoledronic acid to denosumab due to increased serum creatinine level was 59.9 ml/min before administration of zoledronic acid, 40.9 ml/min at the beginning of denosumab treatment, 47.5 ml/min at 3 months after administration of denosumab, and 52.0 ml/min at the last follow-up. There were significant differences. CONCLUSIONS: For the first time, we demonstrated that the renal function of some patients, which had deteriorated following zoledronic acid administration, successfully improved after changing to denosumab.