Regiospecific radiolabelling of Nanofitin on Ni magnetic beads with [18F]FBEM and in vivo PET studies

Sylvestre Dammicco; Marine Goux; Christian Lemaire; Guillaume Becker; Mohamed Ali Bahri; Alain Plenevaux; Mathieu Cinier; André Luxen

doi:10.1016/j.nucmedbio.2017.04.006

Regiospecific radiolabelling of Nanofitin on Ni magnetic beads with [¹⁸F]FBEM and in vivo PET studies

Nucl Med Biol. 2017 Aug:51:33-39. doi: 10.1016/j.nucmedbio.2017.04.006. Epub 2017 Apr 27.

Authors

Sylvestre Dammicco¹, Marine Goux², Christian Lemaire², Guillaume Becker², Mohamed Ali Bahri², Alain Plenevaux², Mathieu Cinier³, André Luxen²

Affiliations

¹ GIGA Cyclotron Research Centre in vivo imaging, University of Liège, Liège, Belgium; Chemistry Department, University of Liège, Liège, Belgium. Electronic address: sdammicco@ulg.ac.be.
² GIGA Cyclotron Research Centre in vivo imaging, University of Liège, Liège, Belgium.
³ Affilogic SAS, Nantes, France.

PMID: 28575696
DOI: 10.1016/j.nucmedbio.2017.04.006

Abstract

Introduction: Nanofitins are low molecular weight, single chain and cysteine-free protein scaffolds able to selectively bind a defined biological target. They derive from Sac7d bacterial protein family and are highly stable over a wide range of pH (0-13) and temperature (Tm ~80°C). Their extreme stability, low cost of production and high tolerability for chemical coupling make Nanofitins a very interesting alternative to antibodies and their fragments. Here, a hexahistidine tagged model Nanofitin (H4) directed against hen egg white lysozyme was radiolabelled and injected in mice to provide a baseline biodistribution and pharmacokinetic profiles to support future Nanofitin development programs.

Method: A single cysteine residue has been genetically inserted in a model Nanofitin and its regioselective radiolabelling has been performed with 4-[¹⁸F]fluorobenzamido-N-ethylamino-maleimide ([¹⁸F]FBEM). The synthesis of [¹⁸F]FBEM has been completely implemented on a radiosynthesis unit (FastLab) including HPLC purification and formulation. Coupling with the [¹⁸F]FBEM has been achieved on a solid support (Ni magnetic beads) allowing rapid purification at room temperature without organic solvent. PET-MRI studies on C57BL/6 mice were conducted after injection of [¹⁸F]FBEM-Cys-H4 in order to access the biodistribution of this Nanofitin model.

Results: Radiochemical yield (decay corrected) of 54±7% (n=4) was obtained after optimization for coupling the [¹⁸F]FBEM to Nanofitin. Pharmacokinetics results of [¹⁸F]FBEM-Cys-H4 revealed a fast clearance through the liver and the kidneys.

Conclusion: An efficient new method on Ni magnetic beads was developed to radiolabelled his-tagged biomolecules with [¹⁸F]FBEM. This procedure was applied on a Nanofitin model Cys-H4 and biodistribution kinetic studies were achieved to evaluate the potential use of Nanofitin for diagnostic imaging. Fast clearance indicates that Nanofitins represent very interesting tools for diagnostic imaging.

Keywords: Biodistribution; Nanofitin; Ni beads; PET; [(18)F]FBEM.

MeSH terms

Animals
Bacterial Proteins / chemistry*
Isotope Labeling
Magnets / chemistry*
Male
Maleimides / chemistry*
Maleimides / pharmacokinetics
Mice
Mice, Inbred C57BL
Microspheres*
Models, Molecular
Nickel / chemistry*
Positron-Emission Tomography / methods*
Protein Conformation
Quality Control
Radiochemistry
Stereoisomerism
Tissue Distribution

Substances

Bacterial Proteins
Maleimides
N-(2-(4-18F-fluorobenzamido)ethyl)maleimide
maleimide
Nickel