This work reports the synthesis, radiolabeling and preliminary biodistribution results in tumor-bearing mice of the 99mTc(CO)3–AOPA colchicine conjugate. The novel ligand was successfully synthesized by conjugation of N-(acetyloxy)-2-picolylamino (AOPA) to deacetylcolchicine via a short carbonyl-methylene linker. Radiolabeling was performed
in high yield with [99mTc(CO)3]+ core. 99mTc(CO)3–AOPA colchicine conjugate was hydrophilic and was stable at room temperature. Biodistribution studies in tumor-bearing mice
showed that 99mTc(CO)3–AOPA colchicine conjugate accumulated in the tumor with good uptake and retention. However, its clearance from normal organs
was not so fast, resulting in poor T/NT ratios. Further modification on the linker or/and 99mTc-chelate to improve the tumor targeting efficacy and in vivo kinetic profiles is currently in progress.