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Kinetic analysis of novel mono‐ and multivalent VHH‐fragments and their application for molecular imaging of brain tumours
Author(s) -
Iqbal U,
Trojahn U,
Albaghdadi H,
Zhang J,
O'ConnorMcCourt M,
Stanimirovic D,
Tomanek B,
Sutherland G,
Abulrob A
Publication year - 2010
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.2010.00742.x
Subject(s) - biodistribution , in vivo , surface plasmon resonance , molecular imaging , chemistry , epidermal growth factor receptor , biophysics , single domain antibody , preclinical imaging , pharmacokinetics , affinities , microbiology and biotechnology , in vitro , antibody , receptor , materials science , biology , stereochemistry , biochemistry , nanotechnology , pharmacology , immunology , nanoparticle
Background and purpose: The overexpression of epidermal growth factor receptor (EGFR) and its mutated variant EGFRvIII occurs in 50% of glioblastoma multiforme. We developed antibody fragments against EGFR/EGFRvIII for molecular imaging and/or therapeutic targeting applications. Experimental approach: An anti–EGFR/EGFRvIII llama single‐domain antibody (EG 2 ) and two higher valency format constructs, bivalent EG 2 ‐hFc and pentavalent V2C‐EG 2 sdAbs, were analysed in vitro for their binding affinities using surface plasmon resonance and cell binding studies, and in vivo using pharmacokinetic, biodistribution, optical imaging and fluorescent microscopy studies. Key results: Kinetic binding analyses by surface plasmon resonance revealed intrinsic affinities of 55 nM and 97 nM for the monovalent EG 2 to immobilized extracellular domains of EGFR and EGFRvIII, respectively, and a 10‐ to 600‐fold increases in apparent affinities for the multivalent binders, V2C‐EG 2 and EG 2 ‐hFc, respectively. In vivo pharmacokinetic and biodistribution studies in mice revealed plasma half‐lives for EG 2 , V2C‐EG 2 and EG 2 ‐hFc of 41 min, 80 min and 12.5 h, respectively, as well as a significantly higher retention of EG 2 ‐hFc compared to the other two constructs in EGFR/EGFRvIII‐expressing orthotopic brain tumours, resulting in the highest signal in the tumour region in optical imaging studies. Time domain volumetric optical imaging fusion with high‐resolution micro‐computed tomography of microvascular brain network confirmed EG 2 ‐hFc selective accumulation/retention in anatomically defined tumour regions. Conclusions: Single domain antibodies can be optimized for molecular imaging applications by methods that improve their apparent affinity and prolong plasma half‐life and, at the same time, preserve their ability to penetrate tumour parenchyma.