Comparison of Systemic Toxicities of 177Lu- DOTMP and 153Sm-EDTMP Administered Intravenously at Equivalent Skeletal Doses to Normal Dogs

Bone-seeking radiopharmaceuticals have been used to effec-tively treat cancer arising from and metastasizing to bone in hu-mans and dogs. The rate of complete tumor control is low, and the geographic distribution of available compounds is limited by their half-lives. This experiment was done to evaluate in nor-mal dogs the toxicity of 177Lu-1,4,7,10-tetraazacyclododec-ane-1,4,7,10-tetramethylene phosphonate (177Lu-DOTMP) used as a potential therapeutic radiopharmaceutical. Methods: Four normal purpose-bred dogs were administered 177Lu-DOTMP at a dose of 8.14 MBq/kg and monitored for 84 d for ev-idence of toxicity in the bone marrow and vital organs. Results: No statistically significant alterations in the biochemical profile, white blood cell count, or platelet count were observed in any dog. Very mild decreases in the red cell count were seen on day 84. No microscopic evidence of toxicity was present at ne-cropsy.Conclusion: The dogs receiving 177Lu-DOTMP tolerated the administration and the effects of the compound without ap-parent clinical toxicity. The results of this experiment support the further evaluation in tumor-bearing dogs of 177Lu-DOTMP as a potential therapy for metastatic bone cancer and primary bone tumors in humans and dogs. Key Words: 177Lu-DOTMP; dogs; bone tumors; bone-seeking radiopharmaceutical