Temporary opening of the blood-brain barrier with the nitrone compound OKN-007

Rheal A Towner; Debra Saunders; Megan Lerner; Robert Silasi Mansat; Tian Yuan; Dylan Barber; Janet Faakye; Adam Nyul-Toth; Anna Csiszar; Beverley Greenwood-Van Meerveld; Nataliya Smith

Temporary opening of the blood-brain barrier with the nitrone compound OKN-007

Am J Nucl Med Mol Imaging. 2021 Oct 15;11(5):363-373. eCollection 2021.

Authors

Rheal A Towner^{1

2}, Debra Saunders¹, Megan Lerner³, Robert Silasi Mansat⁴, Tian Yuan⁵, Dylan Barber¹, Janet Faakye^{6

2}, Adam Nyul-Toth^{6

7}, Anna Csiszar^{6

2}, Beverley Greenwood-Van Meerveld⁵, Nataliya Smith¹

Affiliations

¹ Advanced Magnetic Resonance Center, Oklahoma Medical Research Foundation Oklahoma, OK, USA.
² Department of Neuroscience Program, University of Oklahoma Health Sciences Center Oklahoma, OK, USA.
³ Department of Surgery Research Laboratory, University of Oklahoma Health Sciences Center Oklahoma, OK, USA.
⁴ Cardiovascular Biology, Oklahoma Medical Research Foundation Oklahoma, OK, USA.
⁵ Department of Physiology, University of Oklahoma Health Sciences Center Oklahoma, OK, USA.
⁶ Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center Oklahoma, OK, USA.
⁷ Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH) Szeged, Hungary.

PMID: 34754607
PMCID: PMC8569329

Abstract

The blood-brain barrier (BBB) is usually impermeable to several drugs, which hampers treatment of various brain-related diseases/disorders. There have been several approaches to open the BBB, including intracarotid infusion of hyperosmotic concentrations of arabinose, mannitol, oleic or linoleic acids, or alkylglycerols, intravenous infusion of bradykinin B2, administration of a fragment of the ZO toxin from vibrio cholera, targeting specific components of the tight junctions (e.g. claudin-5) with siRNA or novel peptidomimetic drugs, or the use of ultrasound with microbubbles. We propose the use of a low molecular weight (MW), nitrone-type compound, OKN-007, which can temporarily open up the BBB for 1-2 hours. Gadolinium (Gd)-based compounds assessed ranged in MW from 546 (Gd-DTPA) to 465 kDa (β-galactosidase-Gd-DOTA). We also included an albumin-based CA (albumin-Gd-DTPA-biotin) for assessment, as well as an antibody (Ab) against a neuron-specific biomarker conjugated to Gd-DOTA (anti-EphB2-Gd-DOTA). For the anti-EphB2 (goat Ab)-Gd-DOTA assessment, we utilized an anti-goat Ab conjugated with horse radish peroxidase (HRP) for confirmation of the presence of the anti-EphB2-Gd-DOTA probe. In addition, a Cy5 labeled anti-EphB2 Ab was co-administered with the anti-EphB2-Gd-DOTA probe, and assessed ex vivo. This study demonstrates that OKN-007 may be able to temporarily open up the BBB to augment the delivery of various compounds ranging in MW from as small as ~550 to as large as ~470 kDa. This compound is an investigational new drug for glioblastoma (GBM) therapy in clinical trials. The translational capability for human use to augment the delivery of non-BBB-permeable drugs is extremely high.

Keywords: BBB; Eph-B2; Gd-DOTA; Gd-DTPA; Gd-DTPA-albumin-biotin; OKN-007; contrast-enhanced MRI; in vivo; mice; molecular-targeted MRI; β-galactosidase.