Phase 2 Study of a High Dose of 186Re-HEDP for Bone Pain Palliation in Patients with Widespread Skeletal Metastases

186 Re-1-hydroxyethylidene-1,1-diphosphonate (HEDP) is an attractive radiopharmaceutical for the treatment of bone pain arising from skeletal metastatic lesions. Currently, 186 Re-HEDP is most commonly used in European countries. The aim of this study was to investigate the palliative efficacy and adverse effects of 186Re-HEDP in patients with different types of cancers and skeletal bone pain. Methods: Nineteen (8 male, 11 female) patients with various cancers (breast, prostate, renal cell carcinoma, colon, and neuroendocrine tumors) and painful bone metastases were included in the study. A dose of 1,480‐ 3,330 MBq (40‐90 mCi) of 186Re-HEDP was administered intravenously. The patients’ level of pain relief was assessed by the Visual Analog Scale for 8 wk after treatment and by a weekly blood cell count to evaluate for hematologic toxicity. Results: The overall response rate was 89.5%, and the mean pain score assessed by the Visual Analog Scale was reduced from 9.1 to 5.3 after 1 wk (P 5 0.003). No adverse effects were reported by patients during intravenous administration or for up to 24 h after administration. A flare reaction was seen in 63.2% of patients, mainly during days 1‐3, and lasted for 2‐4 d. There was no significant correlation between the response to therapy and the flare reactions (P . 0.05). The nadir of platelet reduction occurred at the fourth or fifth week and led to platelet infusion in only 4 patients with a low baseline platelet count and diffuse skeletal metastases. Bone marrow suppression occurred in patients receiving higher doses, but no clinical problems were seen except in 2 patients who required packed cell transfusion similar to their prior transfusions. Conclusion: 186Re-HEDP is an effective radiopharmaceutical for the palliative treatment of metastatic bone pain and has minimal adverse effects.