Radioiodinated antibody targeting of the HER-2/neu oncoprotein:: Effects of labeling method on cellular processing and tissue distribution

Monoclonal antibody (MAb) internalization can have a major effect on tumor retention of radiolabel. Two anti HER-2/neu MAbs (TA1 and 520C9) were radioiodinated using the iodogen, N-succinimidyl 5-iodo-3-pyridinecarboxylate (SIPC), and tyramine-cellobiose (TCB) methods. Paired label studies compared internalization and cellular processing of the labeled MAbs by SKOv3 9002-18 ovarian cancer cells in vitro. Intracellular radioiodine activity for 520C9 was up to 2.6 and 3.0 times higher for SIPC and TCB labeling, respectively, compared with iodogen. Likewise, intracellular activity for TAI was up to 2.3 and 2.9 times higher with the SIPC and TCB methods compared with iodogen labeling. Unfortunately, similar advantages in tumor accumulation were not achieved in athymic mice bearing SKOv3 9008-18 ovarian cancer xenografts. NUCL MED BIOL 26;7:781-790, 1999. (C) 1999 Elsevier Science Inc. All rights reserved.