Rhodium-105 Complexes of Polydentate, Aqueous-Soluble, Phosphine Ligands: New Radiochemical Developments towards Radioimmunotherapy

The water-soluble, dithio-bis(hydroxymethyl)phosphine ligands (HOH 2 C) 2 P(CH 2 ) x S(CH 2 ) 3 ((CH 2 ) 4 COOH)S(CH 2 ) x P(CH 2 OH) 2 (X = 2 or 3) were complexed with 105 Rh. 'The new 105 Rh-complexes were formed in high radiochemical purity by addition of 105 RhCl 3 3H 2 O to an aqueous solution of the appropriate ligand framework. The new complexes were formed as singular chemical species and did not undergo in vitro decomposition for ≤24 hours as indicated by high performance liquid chromatographic analyses. In vivo bio-distribution analyses of the new complexes indicate that the primary mode of excretion is the renal-urinary pathway. Results of this study suggest the potential development of new radiop-harmaceuticals for the treatment of human metastases via conjugation of the new 105 Rh-complexes to site-specific biomolecular vectors.