Development of a radiolabeled caninized anti-EGFR antibody for comparative oncology trials
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Judit Fazekas-Singer1,2, Neydher Berroterán-Infante3,4, Christina Rami-Mark2,3,4, Monika Dumanic3, Miroslawa Matz2, Michael Willmann5, Fritz Andreae6, Josef Singer2,3,7, Wolfgang Wadsak3,4,8, Markus Mitterhauser3,9 and Erika Jensen-Jarolim1,2
1Comparative Medicine, The Interuniversity Messerli Research Institute of the University of Veterinary Medicine Vienna, Medical University Vienna, and University of Vienna, Vienna, Austria
2Institute of Pathophysiology and Allergy Research, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
3Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
4Institute of Inorganic Chemistry, University of Vienna, Vienna, Austria
5Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Vienna, Austria
6piCHEM Forschungs- und Entwicklungs GmbH, Graz, Austria
7Department of Internal Medicine II, University Hospital Krems, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
8CBmed GmbH-Center for Biomarker Research in Medicine, Graz, Austria
9LBI Applied Diagnostics, Vienna, Austria
Erika Jensen-Jarolim, email: [email protected]
Keywords: epidermal growth factor receptor, radio-immunotherapy, canine mammary carcinoma, canine antibody, comparative oncology
Received: August 02, 2017 Accepted: August 23, 2017 Published: September 15, 2017
Due to large homology of human and canine EGFR, dogs suffering from spontaneous EGFR+ cancer can be considered as ideal translational models. Thereby, novel immunotherapeutic compounds can be developed for both human and veterinary patients. This study describes the radiolabeling of a canine anti-EGFR IgG antibody (can225IgG) with potential diagnostic and therapeutic value in comparative clinical settings. Can225IgG was functionalized with DTPA for subsequent chelation with the radionuclide 99mTc. Successful coupling of 10 DTPA molecules per antibody on average was proven by significant mass increase in MALDI-TOF spectroscopy, gel electrophoresis and immunoblots. Following functionalization and radiolabeling, 99mTc-DTPA-can225IgG fully retained its binding capacity towards human and canine EGFR in flow cytometry, immuno- and radioblots, and autoradiography. The affinity of radiolabeled can225IgG was determined to KD 0.8 ±0.0031 nM in a real-time kinetics assay on canine carcinoma cells by a competition binding technique. Stability tests of the radiolabeled compound identified TRIS buffered saline as the ideal formulation for short-term storage with 87.11 ±6.04% intact compound being still detected 60 minutes post radiolabeling. High stability, specificity and EGFR binding affinity pinpoint towards 99mTc-radiolabeled can225IgG antibody as an ideal lead compound for the first proof-of-concept diagnostic and therapeutic applications in canine cancer patients.
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