title: No-carrier-added 123I-MIBG: an initial clinical study in patients with phaeochromocytoma.
abstract: Radioiodinated meta-iodobenzylguanidine (MIBG) is used routinely for imaging and targeted radiotherapy of tumours derived from the neural crest. Since active uptake of MIBG by the noradrenaline transporter (NAT) makes a greater contribution to total drug accumulation than passive uptake when MIBG is present at low concentrations, tumour-specific uptake should be enhanced by the administration of lower molar amounts of MIBG. This could be achieved through the use of MIBG with a high specific activity. Commercially available preparations of 123I-MIBG have specific activities of approximately 200 MBq.mg-1. We have synthesized and used no-carrier-added (n.c.a.) 123I-MIBG produced by an iododesilylation reaction (specific activity 0.7 TBq.mg-1). We report here the first clinical studies comparing the commercially available and n.c.a. MIBG diagnostic preparations. Five patients with known phaeochromocytoma were studied. Unlike studies in animal models, no consistent improvement in tumour uptake was observed with the n.c.a. material. A larger patient group is required to determine whether there are significant differences between the two preparations, before proceeding to studies at therapeutic activity levels of n.c.a. 131I-MIBG. Even with no improvement in tumour uptake, n.c.a. MIBG may be the favoured formulation for therapeutic applications to reduce the molar amount of drug injected.
authors.affiliation: West of Scotland Radionuclide Dispensary, North Glasgow Hospitals University NHS Trust, Western Infirmary, UK. j.owens@clinmed.gla.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Owens
authors.forename: A A
authors.initials: AA
authors.lastname: Bolster
authors.forename: J E
authors.initials: JE
authors.lastname: Prosser
authors.forename: S
authors.initials: S
authors.lastname: Cunningham
authors.forename: R J
authors.initials: RJ
authors.lastname: Mairs
authors.forename: J B
authors.initials: JB
authors.lastname: Neilly
authors.forename: N S
authors.initials: NS
authors.lastname: Reed
authors.forename: T E
authors.initials: TE
authors.lastname: Hilditch
mesh_terms: D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics*; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism*; D000328:Adult; D002626:Chemistry, Pharmaceutical; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010673:Pheochromocytoma / Q000000981:diagnostic imaging / Q000378:metabolism*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine