¹⁷⁷Lu-EDTMP for palliation of pain from bone metastases in patients with prostate and breast cancer: a phase II study

The purpose of this study was to evaluate the efficacy and safety of ¹⁷⁷Lu-EDTMP for pain palliation in patients with bone metastases from castration-resistant prostate and breast cancer. The secondary objective was to compare low-dose and high-dose ¹⁷⁷Lu-EDTMP in bone pain palliation.

Included in the study were 44 patients with documented breast carcinoma (12 patients; age 47 ± 13 years) or castration-resistant prostate carcinoma (32 patients; age 66 ± 9 years) and skeletal metastases. Patients were randomized into two equal groups treated with ¹⁷⁷Lu-EDTMP intravenously at a dose of 1,295 MBq (group A) or 2,590 MBq (group B). Pain palliation was evaluated using a visual analogue score (VAS), analgesic score (AS) and Karnofsky performance score (KPS) up to 16 weeks. Toxicity was assessed in terms of haematological and renal parameters.

The overall response rate (in all 44 patients) was 86 %. Complete, partial and minimal responses were seen in 6 patients (13 %), 21 patients (48 %) and 11 patients (25 %), respectively. A favourable response was seen in 27 patients (84 %) with prostate cancer and in 11 patients (92 %) with breast cancer. There was a progressive decrease in the VAS from baseline up to 4 weeks (p < 0.05). Also, AS decreased significantly from 1.8 ± 0.7 to 1.2 ± 0.9 (p < 0.0001). There was an improvement in quality of life of the patients as reflected by an increase in mean KPS from 56 ± 5 to 75 ± 7 (p < 0.0001). The overall response rate in group A was 77 % compared to 95 % in group B (p = 0.188). There was a significant decrease in VAS and AS accompanied by an increase in KPS in both groups. Nonserious haematological toxicity (grade I/II) was observed in 15 patients (34 %) and serious toxicity (grade III/IV) occurred in 10 patients (23 %). There was no statistically significant difference in haematological toxicity between the groups.

¹⁷⁷Lu-EDTMP was found to be a safe and effective radiopharmaceutical for bone pain palliation in patients with metastatic prostate and breast carcinoma. There were no differences in efficacy or toxicity between patients receiving low-dose and high-dose ¹⁷⁷Lu-EDTMP.