Comparison of oncophilic radiopharmaceuticals, *I‐fibrinogen, ⁶⁷Ga‐ citrate, ¹¹¹In‐bleomycin, and *I‐bleomycin in tumor‐bearing mice

The pharmacokinetics of ⁶⁷Ga‐citrate, ¹¹¹‐bleomycin, *I‐bleomycin, and *I‐fibrinogen were compared in a murine KHJJ tumor model in order to assess their relative potential as agents for in vivo detection of cancer. Although all four agents have been reported to be clinically efficacious, in this tumor model, *I‐fibrinogen and ⁶⁷Ga‐citrate had the greatest tumor accumulation with maximum concentrations of 11.7% and 10.5% respectively. However, both these radiopharmaceuticals cleared slowly from the blood and animal. The maximum tumor concentrations of ¹¹¹In‐bleomycin and *I‐bleomycin were 2.9% and 2.6% respectively, but *I‐bleomycin had the advantage of rapid clearance from the blood and animal. ⁶⁷Ga‐citrate did not achieve its maximum tumor concentration until 24 hours after administration, whereas the other radiopharmaceuticals achieved maximum tumor concentration within several hours of administration. From these observations ¹²³I‐bleomycin seems to deserve clinical trials in patients. ¹²³I‐fibrinogen appears to have significant oncophilic potential if its clearance from the animal can be accelerated without altering its accumulation in the tumor. Cancer 40:2923‐2929, 1977.