Cobalt 57 bleomycin is a clinically useful tumor localizing agent, but attempts to label bleomycin (BLEO) with other radionuclides have been made because of the long physical half life of 57Co. As an alternative labeling approach, they iodinated BLEO both directly on the imidazole ring and indirectly by reaction with N succinimidyl 3 (4 hydroxy, 3 iodophenyl) propionate. Directly iodinated BLEO retained antibacterial activity, but in tumor bearing rats it showed a lower tumor to blood ratio (2.3) at 2 hr than did 57Co BLEO (11.8). The antibacterial activity of the indirectly labeled BLEO was markedly reduced and this material showed a tumor to blood ratio of 0.55 at 2 hr. The radioiodinated bleomycins are not suitable substitutes for 57Co BLEO as tumor imaging radiopharmaceuticals.
|Number of pages||4|
|Journal||Journal of Nuclear Medicine|
|State||Published - Dec 1 1976|