Anti-EGFRvIII monoclonal antibody armed with ¹⁷⁷Lu: in vivo comparison of macrocyclic and acyclic ligands

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• 作者：Marc Hens ; Ganesan Vaidyanathan ; Xiao-Guang Zhao ; Darell D. Bigner ; Michael R. Zalutsky
• 关键词：Lu-177 ; Radioimmunotherapy ; MeO-DOTA ; 1B4M-DTPA
• 刊名：Nuclear Medicine and Biology
• 出版年：2010
• 出版时间：October 2010
• 年：2010
• 卷：37
• 期：7
• 页码：741-750
• 全文大小：808 K

文摘

Introduction

Monoclonal antibody (mAb) L8A4 binds specifically to the epidermal growth factor receptor variant III (EGFRvIII) that is present on gliomas but not on normal tissues, and is internalized rapidly after receptor binding. Because of the short range of its β-emissions, labeling this mAb with ¹⁷⁷Lu would be an attractive approach for the treatment of residual tumor margins remaining after surgical debulking of brain tumors.

Materials and Methods

L8A4 mAb was labeled with ¹⁷⁷Lu using the acyclic ligands [(R)-2-amino-3-(4-isothiocyanatophenyl)propyl]-trans-(S,S)-cyclohexane-1,2-diamine-pentaacetic acid (CHX-A″-DTPA) and 2-(4-isothiocyanatobenzyl)-6-methyldiethylene-triaminepentaacetic acid (1B4M-DTPA), and the macrocyclic ligands S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid (C-DOTA) and α-(5-isothiocyanato-2-methoxyphenyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (MeO-DOTA). Paired-label tissue distribution experiments were performed in athymic mice bearing subcutaneous EGFRvIII-expressing U87.ΔEGFR glioma xenografts over a period of 1 to 8 days to directly compare ¹⁷⁷Lu-labeled L8A4 to L8A4 labeled with ¹²⁵I using N-succinimidyl 4-guanidinomethyl-3-[¹²⁵I]iodobenzoate ([¹²⁵I]SGMIB).

Results

Except with C-DOTA, tumor uptake for the ¹⁷⁷Lu-labeled mAb was significantly higher than the co-administered radioiodinated preparation; however, this was also the case for spleen, liver, bone and kidneys. Tumor/normal tissue ratios for ¹⁷⁷Lu-1B4M-DTPA-L8A4 and, to an even greater extent, ¹⁷⁷Lu-MeO-DOTA-L8A4 were higher than those for [¹²⁵I]SGMIB-L8A4 in most other tissues.

Conclusions

Tumor and normal tissue distribution patterns for this anti-EGFRvIII mAb were dependent on the nature of the bifunctional chelate used for ¹⁷⁷Lu labeling. Optimal results were obtained with 1B4M-DTPA and MeO-DOTA, suggesting no clear advantage for acyclic vs. macrocyclic ligands for this application.