Production and characterisation of a C595 antibody-Tc-99m conjugate for immunoscintigraphy of bladder cancer

Current radiological techniques for staging bladder cancer are inaccurate, especially in the identification of pelvic lymph node metastases. Immunosci ntigraphy has the potential to offer improved staging for bladder cancer. T he aim of this study was to label the anti-MUC1 monoclonal antibody C595 wi th (99m)technetium (Tc), the most widely used diagnostic radionuclide, and assess the potential of the resultant conjugate for intravenous immunoscint igraphy of bladder cancer. A direct, reduction-mediated technique was used to label the antibody. The resultant conjugate was shown to be highly immun oreactive, stable and bound specifically to MUC1. The ability of the conjug ate to bind to bladder tumours was demonstrated in an ex vivo model where t he mean tumour:normal urothelial uptake was 5.7:1 and by intravesical admin istration in patients with bladder cancer where the mean tumour:normal urot helial uptake was 20.4:1. The ability of the conjugate to localise MUC1-exp ressing tumours was demonstrated in a nude mouse xenograft model. A conjuga te of (99m)TcC595 has been produced and characterised, and it may be suitab le for intravenous immunoscintigraphy, a potential novel staging tool for b ladder cancer.