Structure-Guided Molecular Engineering of a Vascular Endothelial Growth Factor Antagonist to Treat Retinal Diseases

Rakeeb Kureshi; Angela Zhu; Jikui Shen; Stephany Y Tzeng; Leilani R Astrab; Paul R Sargunas; Jordan J Green; Peter A Campochiaro; Jamie B Spangler

doi:10.1007/s12195-020-00641-0

Structure-Guided Molecular Engineering of a Vascular Endothelial Growth Factor Antagonist to Treat Retinal Diseases

Cell Mol Bioeng. 2020 Jul 31;13(5):405-418. doi: 10.1007/s12195-020-00641-0. eCollection 2020 Oct.

Authors

Rakeeb Kureshi¹, Angela Zhu², Jikui Shen^{3

4}, Stephany Y Tzeng^{1

5

6}, Leilani R Astrab^{1

2}, Paul R Sargunas², Jordan J Green^{1

2

3

5

6

7

8}, Peter A Campochiaro^{3

4}, Jamie B Spangler^{1

2

5}

Affiliations

¹ Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD USA.
² Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, MD USA.
³ Department of Ophthalmology, The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD USA.
⁴ Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD USA.
⁵ Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, Baltimore, MD USA.
⁶ Insititute for Nanobiotechnology, Johns Hopkins University, Baltimore, MD USA.
⁷ Department of Materials Science & Engineering, Johns Hopkins University, Baltimore, MD USA.
⁸ Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD USA.

Abstract

Background: Ocular neovascularization is a hallmark of retinal diseases including neovascular age-related macular degeneration and diabetic retinopathy, two leading causes of blindness in adults. Neovascularization is driven by the interaction of soluble vascular endothelial growth factor (VEGF) ligands with transmembrane VEGF receptors (VEGFR), and inhibition of the VEGF pathway has shown tremendous clinical promise. However, anti-VEGF therapies require invasive intravitreal injections at frequent intervals and high doses, and many patients show incomplete responses to current drugs due to the lack of sustained VEGF signaling suppression.

Methods: We synthesized insights from structural biology with molecular engineering technologies to engineer an anti-VEGF antagonist protein. Starting from the clinically approved decoy receptor protein aflibercept, we strategically designed a yeast-displayed mutagenic library of variants and isolated clones with superior VEGF affinity compared to the clinical drug. Our lead engineered protein was expressed in the choroidal space of rat eyes via nonviral gene delivery.

Results: Using a structure-informed directed evolution approach, we identified multiple promising anti-VEGF antagonist proteins with improved target affinity. Improvements were primarily mediated through reduction in dissociation rate, and structurally significant convergent sequence mutations were identified. Nonviral gene transfer of our engineered antagonist protein demonstrated robust and durable expression in the choroid of treated rats one month post-injection.

Conclusions: We engineered a novel anti-VEGF protein as a new weapon against retinal diseases and demonstrated safe and noninvasive ocular delivery in rats. Furthermore, our structure-guided design approach presents a general strategy for discovery of targeted protein drugs for a vast array of applications.

Keywords: Affinity engineering; Directed evolution; Nonviral gene therapy; Ocular neovascularization; Vascular endothelial growth factor receptor.

Abstract

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