Metal complexes of bleomycin: evaluation of [Rh-105]-bleomycin for use in targeted radiotherapy.

Abstract Bleomycin has been used as a carrier for several radioisotopes; however, its potential for clinical use has been limited either by the in vivo stability of the complexes or the half-life of the isotope used. The chemical, biological, and radiological properties of 105 Rhodium appear to make it an ideal choice for targeted radiotherapy. The synthesis and purification of a hereto unreported 105 Rhodium–bleomycin ( 105 Rh-BLM) complex is described. The stability of this complex in plasma is sufficient to allow targeted delivery of the radioisotope. 57 Cobalt–bleomycin was studied under identical conditions for comparative purposes. The suitability of 105 Rh-BLM for targeted therapy, which appears to be limited by the renal clearance of this agent, is discussed.