Duration of Suppression of Bone Turnover Following Treatment With Zoledronic Acid in Men With Metastatic CRPC

The bone is the most common site of metastasis in men with prostate cancer, and that bone metastases are associated with a significant risk of SREs. Prevention and delay in onset of SREs has been demonstrated with use of ZA. The optimal dosing frequency of ZA is not known in this population but it is usually given every 3-4 weeks, whereas injections as infrequently as once yearly protect from bone loss in patients without bone metastases who are receiving ADT. uNTX, sCTX and BAP are markers of bone turnover and bone formation that are suppressed in response to ZA and are associated with the likelihood of development of an SRE. In this study, we propose to determine the duration of suppression of bone turnover (all uNTX, sCTX and BAP) in response to a single dose of ZA in patients with castration resistant prostate cancer metastatic to bone. Our objectives for this study: 1. To estimate the proportion of patients with suppression of bone turnover at 12 weeks after administration of a single dose of ZA. 2. To estimate the distribution of duration of suppression of bone turnover up to 12 weeks after administration of ZA. 3. To evaluate the frequency of SREs experienced by patients in this population. 4. To measure quality of life and presence of bone pain over a 12 week period in this patient population by utilizing the Functional Assessment of Cancer Therapy - Bone Pain (FACT-BP) and Brief Pain Inventory (BPI) questionnaires.