Development, optimization, and validation of novel anti-TEM1/CD248 affinity agent for optical imaging in cancer

作者:Li Chunsheng*; Wang Junying; Hu Jia; Feng Yi; Hasegawa Kosei; Peng Xiaohui; Duan Xingmei; Zhao Aizhi; Mikitsh John L; Muzykantov Vladimir R; Chacko Ann Marie; Pryma Daniel A; Dunn Steven M; Coukos George
来源:Oncotarget, 2014, 5(16): 6994-7012.
DOI:10.18632/oncotarget.2188

摘要

Tumor Endothelial Marker-1 (TEM1/CD248) is a tumor vascular marker with high therapeutic and diagnostic potentials. Immuno-imaging with TEM1-specific antibodies can help to detect cancerous lesions, monitor tumor responses, and select patients that are most likely to benefit from TEM1-targeted therapies. In particular, near infrared(NIR) optical imaging with biomarker-specific antibodies can provide real-time, tomographic information without exposing the subjects to radioactivity. To maximize the theranostic potential of TEM1, we developed a panel of all human, multivalent Fc-fusion proteins based on a previously identified single chain antibody (scFv78) that recognizes both human and mouse TEM1. By characterizing avidity, stability, and pharmacokinectics, we identified one fusion protein, 78Fc, with desirable characteristics for immuno-imaging applications. The biodistribution of radiolabeled 78Fc showed that this antibody had minimal binding to normal organs, which have low expression of TEM1. Next, we developed a 78Fc-based tracer and tested its performance in different TEM1-expressing mouse models. The NIR imaging and tomography results suggest that the 78Fc-NIR tracer performs well in distinguishing mouse-or human-TEM1 expressing tumor grafts from normal organs and control grafts in vivo. From these results we conclude that further development and optimization of 78Fc as a TEM1-targeted imaging agent for use in clinical settings is warranted.