Novel VEGF Decoy Receptor Fusion Protein Conbercept Targeting Multiple VEGF Isoforms Provide Remarkable Anti-Angiogenesis Effect In Vivo

Qin Wang,Tao Li,Xiao Ke,Hui Wang,Zhigang Wu,Quan Wu,Delun Luo,Bhaskar Saha

doi:10.1371/journal.pone.0070544

Abstract

VEGF family factors are known to be the principal stimulators of abnormal angiogenesis, which play a fundamental role in tumor and various ocular diseases. Inhibition of VEGF is widely applied in antiangiogenic therapy. Conbercept is a novel decoy receptor protein constructed by fusing VEGF receptor 1 and VEGF receptor 2 extracellular domains with the Fc region of human immunoglobulin. In this study, we systematically evaluated the binding affinity of conbercept with VEGF isoforms and PlGF by using anti-VEGF antibody (Avastin) as reference. BIACORE and ELISA assay results indicated that conbercept could bind different VEGF-A isoforms with higher affinity than reference. Furthermore, conbercept could also bind VEGF-B and PlGF, whereas Avastin showed no binding. Oxygen-induced retinopathy model showed that conbercept could inhibit the formation of neovasularizations. In tumor-bearing nude mice, conbercept could also suppress tumor growth very effectively in vivo. Overall, our study have demonstrated that conbercept could bind with high affinity to multiple VEGF isoforms and consequently provide remarkable anti-angiogenic effect, suggesting the possibility to treat angiogenesis-related diseases such as cancer and wet AMD etc.

Highlights

The pathological angiogenesis is a critical hallmark of human diseases such as the cancer [1] and the wet form of age-related macular degeneration (AMD) [2] – the leading cause of blindness in the elderly population
The binding specificity and efficiency of conbercept and Avastin with vascular endothelial growth factor (VEGF) isoforms and placental growth factor (PlGF) were first examined by ELISA (Figure 2)
Conbercept binds VEGF-B and PlGF with relative affinity of 2 nM and 52 nM respectively, whereas Avastin shows no detectable binding to VEGF-B and PlGF

Summary

Introduction

The pathological angiogenesis is a critical hallmark of human diseases such as the cancer [1] and the wet form of age-related macular degeneration (AMD) [2] – the leading cause of blindness in the elderly population. Compelling evidences have demonstrated that vascular endothelial growth factor (VEGF) plays a pivotal role in the abnormal angiogenesis process [3]. VEGF has become a key target in antiangiogenic therapy [4]. There are five members in VEGF family: VEGF-A, -B, -C, -D and placental growth factor (PlGF) [5]. VEGF-A is the first discovered and the most well-studied member [6]. Alternative exon splicing and proteolytic cleavage generated several distinct VEGF-A isoforms, respectively named VEGF121, VEGF165, and VEGF162. VEGF-A isoforms are all active as dimers, differing principally in their size and ability to bind heparin or neuropilins. Isoforms of VEGF-B and PlGF, which differ in their capacity to bind heparin, are produced by alternative splicing

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Conclusion