| abstract |
A peptide-chelate conjugate with affinity for the ST receptor is disclosed, wherein the chelate is tetradentate. A low-molecular weight heat-stable toxi n is produced by enterotoxic strains of E. Coli. This toxin, known as ST peptide, mediates acute diarrheal disease by binding to its receptor on colorectal cells and stimulating guanylate cyclase. Gastrointestinal mucosal cells specifically express the ST receptor and the expression persist after colonic and rectal mucosal cells undergo malignant neoplasic transformation. The peptide-chelate conjugate of the invention may be labelled with a radiometal to provide a metal complex. In a preferred embodiment, the radiometal is 99mtc, and the chelating agent is selected from: diaminedioxim e, diaminediphenol, N3S, N4 and N2S2 Ligands. A radiopharmaceutical composition comprising the metal complex is provided, which is suitable for the diagnost ic imaging of colorectal cancer. Also provided for in the invention is a kit fo r the preparation of the radiopharmaceutical preparation. |