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

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.

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.

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.

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.