Phase II trial investigating the effects of zoledronate and dexamethasone in hormone resistant prostate cancer

Abstract

15629 Background: Response rates to second line therapy in hormone resistant prostate cancer have been shown to be relatively low. Current options of management include dexamethasone, zoledronate or more recently, cytotoxic chemotherapy. Many trials have studied their effects as monotherapy. The aim of this study is to assess the efficacy and safety of the combination of zoledronate and dexamethasone in these patients. Methods: 20 patients were identified in 2004–2005. All had histologically confirmed prostatic adenocarcinoma and biochemically confirmed hormone resistance. All patients had bone metastases as confirmed on radionuclide imaging. Treatment consisted of 6 cycles of zoledronate at a dose of 4 mg, given at 4 weekly intervals, in combination with dexamethasone 2–4 mg once a day. Calcium/vitamin D supplementation was given throughout the zoledronate treatment. Data was collected prospectively on serum PSA, quality of life and pain score. Results: Of the 20 patients in the study, 11 completed the full 24 weeks of treatment. Reasons for not completing the study included disease progression, treatment toxicity, fracture and death. The overall response rate, as defined by an initial fall of serum PSA of more than 50%, was 35% (7 out of 20 patients). In those who responded, the sustained fall in PSA, during the trial period, lasted on average 3.0 months. Conclusion: This study has demonstrated clinically significant effects on tumour response for the combination of zoledronate and dexamethasone in hormone resistant prostate carcinoma. With the emergence of newer chemotherapeutic agents, this combination could be used as an effective, but less toxic alternative. No significant financial relationships to disclose.