Radioimmunotargeting of malignant glioma by monoclonal antibody D2C7 reactive against both wild-type and variant III mutant epidermal growth factor receptors

• Published in: Nuclear medicine and biology 2012-01, Vol.39 (1), p.23-34
• Main Authors: Zalutsky, Michael R, Boskovitz, Abraham, Kuan, Chien-Tsun, Pegram, Charles N, Ayriss, Joanne, Wikstrand, Carol J, Buckley, Anne F, Lipp, Eric S, Herndon, James E, McLendon, Roger E, Bigner, Darell D
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Monoclonal - pharmacokinetics; Antibodies, Monoclonal - therapeutic use; Biological and medical sciences; Brain tumors; Cell Line, Tumor; Drug development; EGFRvIII; Epidermal growth factor receptor; Epidermal growth factor receptors; Female; Flow Cytometry; Glioblastoma multiforme; Glioma; Glioma - metabolism; Glioma - radiotherapy; Humans; Iodine Radioisotopes - pharmacokinetics; Iodine Radioisotopes - therapeutic use; Male; Medical sciences; Mice; Mice, Inbred BALB C; Mice, Nude; Middle Aged; Monoclonal antibodies; Monoclonal antibody; Neurology; Nuclear medicine; Radiology; Receptor, Epidermal Growth Factor - metabolism; surface plasmon resonance; Tissue Distribution; Tumor cells; Tumors; Tumors of the nervous system. Phacomatoses; Xenografts
• ISSN: 0969-8051; 1872-9614
• DOI: 10.1016/j.nucmedbio.2011.06.005

Abstract Introduction Malignant glioma remains a significant therapeutic challenge, and immunotherapeutics might be a beneficial approach for these patients. A monoclonal antibody (MAb) specific for multiple molecular targets could expand the treatable patient population and the fraction of tumor cells targeted, with potentially increased efficacy. This motivated the generation of MAb D2C7, which recognizes both wild-type epidermal growth factor receptor (EGFRwt) and a tumor-specific mutant, EGFRvIII. Methods D2C7 binding affinity was determined by surface plasmon resonance and its specificity characterized through comparison to EGFRwt-specific EGFR.1 and EGFRvIII-specific L8A4 MAbs by flow cytometry and immunohistochemical analysis. The three MAbs were labeled with125 I or131 I using Iodogen, and paired-label internalization assays and biodistribution experiments in athymic mice with human tumor xenografts were performed. Results The affinity of D2C7 for EGFRwt and EGFRvIII was 5.2×109 M−1 and 3.6×109 M−1 , and cell-surface reactivity with both receptors was documented by flow cytometry. Immunohistochemical analyses revealed D2C7 reactivity with malignant glioma tissue from 90 of 101 patients. Internalization assays performed on EGFRwt-expressing WTT cells and EGFRvIII-expressing NR6M cells indicated a threefold lower degradation of125 I-labeled D2C7 compared with131 I-labeled EGFR.1. Uptake of125 I-labeled D2C7 in NR6M xenografts (52.45±13.97 %ID g−1 on Day 3) was more than twice that of131 I-labeled L8A4; a threefold to fivefold tumor delivery advantage was seen when compared to131 I-labeled EGFR.1 in mice with WTT xenografts. Conclusions These results suggest that D2C7 warrants further evaluation for the development of MAb-based therapeutics against cancers expressing EGFRwt and EGFRvIII.