IN-VIVO STUDY OF A TECHNETIUM-LABELED ANTI-EGFR MOAB

Epithelial Growth Factor receptors (EGFr) are normally present in all the epithelial cells, but their overexpression is closely related to p resence of cancer. We have raised EGF-competitive antibody against EGF r and have labelled it with I-131 and technetium. The ability of this antibody to bind to A431 cells to be internalized has been tested on A 431 cells cultures. Its ability to give scintigraphic images of epithe lial tumors has been tested on nu/nu balb c mice xenografted with A431 cells. The labelled antibody is well internalized by cultured cells. Xenografted tumors are clearly imaged both by I-131 and Tc-99m anti EG Fr MoAb. Tc-99m labelling is very interesting. The tumor background ra tio was 0.72 +/- 0.2 for Tc-99m and 0.40 +/- 0.6 for I-131 labelling. Moreover very high uptake of Tc-99m MoAb was obtained 2 hours after in jection whereas the I-131 antibody required 24 hours.