[177Lu]Lu-EDTMP —a bone pain palliating agent: pharmacokinetics, biodistribution, safety profile and clinical evaluation in osseous metastatic patients

Abstract

Background

[¹⁷⁷Lu]Lu-EDTMP has emerged as a promising radiopharmaceutical for the palliation of pain caused by osseous metastases. This phase I/II study comprehensively evaluate the pharmacokinetics, biodistribution, clinical efficacy, and safety profile of [¹⁷⁷Lu]Lu-EDTMP, in patients with skeletal metastases from breast and prostate cancer.

Methods

A total of 27 patients with skeletal metastases were included in the study. Pharmacokinetics and biodistribution were analyzed in 17 patients through whole-body gamma camera imaging and quantification at multiple time points. Clinical efficacy and safety were evaluated in 18 patients receiving either low (1.3 GBq) or high (2.6 GBq) administered activity. Pain palliation was assessed using visual analog scale scores, analgesic usage (frequency and type), mobility scores, and Karnofsky performance status. The safety profile was determined through hematological and biochemical monitoring over 12 weeks.

Results

[¹⁷⁷Lu]Lu-EDTMP demonstrated rapid blood clearance, with negligible residual activity at 24 h. Urinary excretion accounted for over 30% of administered activity at 24 h. Bone uptake increased progressively to over 70%.

Scintigraphy revealed selective uptake in metastases, improving lesion-to-bone and lesion-to-soft tissue ratios. Both low (1.3 GBq) and high (2.6 GBq) activity groups showed significant pain relief, with faster, longer-lasting effects in the high-dose group, reducing opioid/NSAID use. No Grade III/IV myelotoxicity or major renal/hepatic events occurred.

Conclusion

[¹⁷⁷Lu]Lu-EDTMP is a safe and effective bone pain palliation agent, with favorable pharmacokinetics, targeted skeletal uptake, and minimal toxicity. These findings support its potential use as an alternative radiopharmaceutical for pain palliation in patients with skeletal metastases.

Clinical trial number

Not applicable.