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

• Published in: Oncotarget Vol. 5; no. 16; pp. 6994 - 7012
• Main Authors: Li, C, Wang, J, Hu, J, Feng, Y, Hasegawa, K, Peng, X, Duan, X, Zhao, A, Mikitsh, J.L, Muzykantov, V.R, Chacko, A.-M, Pryma, D.A, Dunn, S.M, Coukos, G
• Format: Journal Article
• Language: English
• Published: United States Impact Journals, LLC 30.08.2014; Impact Journals LLC
• Subjects: animal; animal cell; animal experiment; animal model; Animals; Antigens, CD; Antigens, CD - analysis; Antigens, CD - immunology; Antigens, Neoplasm; Antigens, Neoplasm - analysis; Antigens, Neoplasm - immunology; binding affinity; breast cancer; cancer graft; CD248 protein; Cell Line, Tumor; chemistry; controlled study; disease model; Disease Models, Animal; endosialin; enzyme linked immunosorbent assay; fluorescence imaging; genetic transfection; genetics; Heterografts; human; Humans; hybrid protein; immunoglobulin fragment; Immunoglobulin Fragments; Immunoglobulin Fragments - chemistry; Immunoglobulin Fragments - genetics; Immunoglobulin Fragments - immunology; immunoreactivity; in vitro study; in vivo study; isotope labeling; leukocyte antigen; lymph node metastasis; Mice; Mice, Nude; mouse; near infrared imaging system; neoplasm; Neoplasms; Neoplasms - chemistry; Neoplasms - immunology; nonhuman; Optical Imaging; ovary cancer; patient selection; positron emission tomography; process optimization; protein purification; protein stability; radioactivity; Recombinant Fusion Proteins; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - pharmacokinetics; Research Paper; single chain fragment variable antibody; single photon emission computer tomography; thermostability; Tissue Distribution; tomography; tracer; Transfection; tumor antigen; tumor marker; tumor vascularization; validation process; Western blotting
• ISSN: 1949-2553; 1949-2553
• DOI: 10.18632/oncotarget.2188

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.