Biodistribution of 99mTc-labeled anti-human epidermal growth factor receptor (EGF-R) humanized monoclonal antibody h-R3 in a xenograft model of human lung adenocarcinoma

The anti-human epidermal growth factor receptor (EGF-R) humanized monoclonal antibody (MAb) h-R3 is an (IgG(1)), which binds to an extracellular domain of EGF-R. It was used to evaluate the biodistribution on nude mice xenografted with H-125 human lung adenocarcinoma cell line. Results were compared with its murine version of the MAb ior-egf/r3. Twenty-one athymic female 4NMRI nu/nu mice were injected intraperitoneally with 10 mu g/100 mu Ci of Tc-99m-labeled MAbs. Immunoreactivity of Tc-99m-labeled h MAbs were measured by enzyme-linked immunosorbent assay (ELISA) on H-125 cell line and the immunoreactive fractions was determined by the Lindmo method. Among all organs, significant accumulation was found in serum (27.05 +/- 2.08 %ID/g) and tumor (3.903 +/- 0.89 %ID/g) at 4 h after injection, These values decreased to 5.03 +/- 0.50 %ID/g and 2.19 +/- 0.56 %ID/g for serum and tumor, respectively. The immunoreactive fraction was found to be 0.70, with a correlation coefficient r = 0.9984. With the good biodistribution and tumor uptake of the Tc-99m-labeled humanized antibody h-R3, a phase I diagnostic clinical trial of tumor with epithelial origin should be pursued. NUCL MED BIOL 26;3:275-279, 1999. (C) 1999 Elsevier Science Inc. All rights reserved.