Yuan Xiaopeng, Yang Mingjuan, Chen Xiang, Zhang Xuhua, Sukhadia Shrey, Musolino Najia, Bao Huijing, Chen Tingtao, Xu Chen, Wang Qirui, Santoro Stephen, Ricklin Daniel, Hu Jia, Lin Ruihe, Yang Wei, Li Zhijun, Qin Weijun, Zhao Aizhi, Scholler Nathalie, Coukos George
Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA.
Department of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangdong, China.
Cancer Immunol Immunother. 2018 Feb;67(2):329-339. doi: 10.1007/s00262-017-2101-0.
Tumor endothelial marker 1 (TEM1) has been identified as a novel surface marker upregulated on the blood vessels and stroma in many solid tumors. We previously isolated a novel single-chain variable fragment (scFv) 78 against TEM1 from a yeast display scFv library. Here we evaluated the potential applications of scFv78 as a tool for tumor molecular imaging, immunotoxin-based therapy and nanotherapy. Epitope mapping, three-dimensional (3D) structure docking and affinity measurements indicated that scFv78 could bind to both human and murine TEM1, with equivalent affinity, at a well-conserved conformational epitope. The rapid internalization of scFv78 and scFv78-labeled nanoparticles was triggered after specific TEM1 binding. The scFv78-saporin immunoconjugate also exerted dose-dependent cytotoxicity with high specificity to TEM1-positive cells in vitro. Finally, specific and sensitive tumor localization of scFv78 was confirmed with optical imaging in a mouse tumor model that has highly endogenous mTEM1 expression in the vasculature. Our data indicate that scFv78, the first fully human anti-TEM1 recombinant antibody, recognizes both human and mouse TEM1 and has unique and favorable features that are advantageous for the development of imaging probes or antibody-toxin conjugates for a large spectrum of human TEM1-positive solid tumors.
肿瘤内皮标志物1（TEM1）已被鉴定为一种在许多实体瘤的血管和基质上上调的新型表面标志物。我们之前从酵母展示单链抗体库中分离出一种针对TEM1的新型单链可变片段（scFv）78。在此，我们评估了scFv78作为肿瘤分子成像、基于免疫毒素的治疗和纳米治疗工具的潜在应用。表位作图、三维（3D）结构对接和亲和力测量表明，scFv78可以以等效亲和力在一个保守的构象表位上与人源和鼠源TEM1结合。在特异性结合TEM1后，scFv78和scFv78标记的纳米颗粒迅速内化。scFv78-皂草毒素免疫偶联物在体外对TEM1阳性细胞也具有剂量依赖性细胞毒性且特异性高。最后，在一个血管中高表达内源性小鼠TEM1的小鼠肿瘤模型中，通过光学成像证实了scFv78在肿瘤中的特异性和灵敏定位。我们的数据表明，scFv78作为首个完全人源抗TEM1重组抗体，可识别人类和小鼠TEM1，具有独特且有利的特性，有利于开发用于多种人类TEM1阳性实体瘤的成像探针或抗体-毒素偶联物。
