^99m Tc-labeled DTPA-colchicine dimer with improved tumor uptake

This work reports the synthesis, radiolabeling, and biological studies of ^99m Tc-diethylene triamine pentaacetic acid (DTPA)-colchicine dimer in tumor-bearing mice. The novel colchicine dimer was successfully synthesized by conjugation of DTPA to 2 colchicine biomolecules. The ligand could be labeled by ^99m Tc in high yield to get ^99m Tc-DTPA-colchicine dimer, which was hydrophilic and stable at room temperature. Biodistribution and imaging studies in tumor-bearing mice showed that ^99m Tc-DTPA-colchicine dimer accumulated in the tumor with improved uptake and retention. The results indicate the need for synthetic modification of the parent colchicine derivative and the ^99m Tc-chelate with a view to improve the tumor-targeting efficacy and in vivo kinetic profiles.