BLEDTA II: Synthesis of a new tumor-visualizing derivative of Co(III)-bleomycin

A new bifunctional chelating agent, (S)-1-(p-bromoacetamidobenzyl) ethylenedinitrilotetraacetic acid, has been prepared from L-phenylalanine. Reaction of the chelating agent with the Co(III) complex of the antitumor antibody bleomycin-A₂DM was used to generate a new derivative of Co(III)-bleomyin, BLEDTA II. The product can be radiolabeled quickly by binding a radioactive metal ion to the EDTA group. The in vivo distribution of ¹¹¹In-BLEDTA II in tumor-bearing mice was determined and found to be indistinguishable from that of the clinically useful ¹¹¹In(III)-BLEDTA I complex.