An automated synthesis of 177Lu-EDTMP as an efficient bone-seeking therapeutic radiopharmaceutical

OBJECTIVE: Radiolabeled bisphosphonates have found wide clinical use in nuclear medicine for palliative therapy of bone metastases. 177Lu-EDTMP was used to relieve metastatic bone pain in patients with breast or prostate cancer. The therapeutic efficacy of 177Lu-EDTMP at 1-, 3-, 6-, and 8-weeks post-therapy was evaluated using Standard Pain Scoring Assessment Criteria. In addition, toxicity was evaluated in terms of hematological parameters using the Common Terminology Criteria for Adverse Events V4.0. PATIENTS AND METHODS: A fully automated synthesis of 177Lu-EDTMP was achieved in this study with high radiochemical efficiency and high radiochemical purity. During the study, 75 patients (57 M: 18 F, mean age: 68.0 ± 11.1 years) of breast/prostate cancer with documented skeletal metastases were included. Patients were administered intravenously with 177Lu-EDTMP at a dose rate of 22.2-37.0 MBq/kg following a fully automated synthesis of 177Lu-EDTMP using a disposable cassette system. RESULTS: Among the 75 patients all treated with 177Lu-EDTMP, 59 patients were responsive and the remaining 16 patients did not respond to the therapy. Mean pain score values in the responder group were 5.60 ± 0.5, 4.3 ± 0.1, 2.6 ± 0.4 and 1.4 ± 0.7 at weeks 1, 3, 6, and 8, respectively. Also, the mean pain score decreased from a baseline score of 7.6 ± 1.6 to 1.4 ± 0.7 at week 8 in the responder group. Statistical analysis of the pain score data showed a significant decrease in pain score after each radiopharmaceutical treatment, compared to the baseline scores (p <0.0001). Mild to severe toxicity was observed in two patients each treated with 177Lu-EDTMP. CONCLUSIONS: These findings demonstrated that the 177Lu-EDTMP radiopharmaceutical could be used safely to achieve considerable therapeutic efficacy, in metastatic bone pain palliation together with the safe clinical application and low radiation exposure during preparation.