• Christina Otto, Markus Jensen, Markus Dietlein, Thomas Fischer, Matthias Schmidt, Samir Tawadros, Sarah Maria Börner, Sebastian Alfred Weber, Rüdiger Spitz, Wilhelm Bloch, Frank Berthold, Harald Schicha, and Klaus Schomäcker.
• Department of Nuclear Medicine, University of Cologne, Germany.
• Nucl Med Commun. 2006 Feb 1; 27 (2): 171-8.

PurposeTo evaluate a novel strategy of immunolocalization of human neuroblastoma by targeting the neural cell adhesion molecule (NCAM), which is over-expressed on neuroblastoma.MethodsNCAM expression on the cell surface of established neuroblastoma cells was shown by flow cytometry. A SCID mouse model using IMR5-75 neuroblastoma cells to induce subcutaneous tumour growth was established. 131I was used to label monoclonal NCAM specific ERIC1 antibodies generating the 131I-ERIC1 antibody, which showed a high affinity to NCAM also after labelling (KD=9 x 10(-8) mol . l(-1)).ResultsMeasurement of organ-specific radioactivity showed low organ-specific uptake (5.33%ID/g (percent of injected dose per gram of tissue) after 72 h), which continuously decreased over the 96 h investigation period, demonstrating clearance of radioactivity. In contrast, tumours accumulated radioactivity continuously up to a peak of 42.07%ID/g at the 96 h time point (31.07%ID/g at 72 h). This specific uptake could be blocked by application of unlabelled ERIC1 antibodies. Measurement of blood specific radioactivity revealed a characteristic clearance over the first 72 h. With 37 Gy, tumour-specific radioactivity reached therapeutic doses after 96 h.ConclusionsThese results indicate that 131I-labelled ERIC1 has the ability to probe NCAM-expressing tumour cells in vivo with high efficiency and is a promising reagent for the diagnosis and treatment of NCAM-positive human tumours, especially for neuroblastoma.

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