A dose-escalating toxicology study of the candidate biologic ELP-VEGF

Jamarius P Waller,Gene L Bidwell,Stephen P Burke,Alejandro R Chade,Jason Engel

doi:10.1038/s41598-021-85693-6

Jamarius P Waller, Gene L Bidwell + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-85693-6

Copy DOI

Abstract

Vascular Endothelial Growth Factor (VEGF), a key mediator of angiogenesis and vascular repair, is reduced in chronic ischemic renal diseases, leading to microvascular rarefaction and deterioration of renal function. We developed a chimeric fusion of human VEGF-A121 with the carrier protein Elastin-like Polypeptide (ELP-VEGF) to induce therapeutic angiogenesis via targeted renal VEGF therapy. We previously showed that ELP-VEGF improves renal vascular density, renal fibrosis, and renal function in swine models of chronic renal diseases. However, VEGF is a potent cytokine that induces angiogenesis and increases vascular permeability, which could cause undesired off-target effects or be deleterious in a patient with a solid tumor. Therefore, the current study aims to define the toxicological profile of ELP-VEGF and assess its risk for exacerbating tumor progression and vascularity using rodent models. A dose escalating toxicology assessment of ELP-VEGF was performed by administering a bolus intravenous injection at doses ranging from 0.1 to 200 mg/kg in Sprague Dawley (SD) rats. Blood pressure, body weight, and glomerular filtration rate (GFR) were quantified longitudinally, and terminal blood sampling and renal vascular density measurements were made 14 days after treatment. Additionally, the effects of a single administration of ELP-VEGF (0.1–10 mg/kg) on tumor growth rate, mass, and vascular density were examined in a mouse model of breast cancer. At doses up to 200 mg/kg, ELP-VEGF had no effect on body weight, caused no changes in plasma or urinary markers of renal injury, and did not induce renal fibrosis or other histopathological findings in SD rats. At the highest doses (100–200 mg/kg), ELP-VEGF caused an acute, transient hypotension (30 min), increased GFR, and reduced renal microvascular density 14 days after injection. In a mouse tumor model, ELP-VEGF did not affect tumor growth rate or tumor mass, but analysis of tumor vascular density by micro-computed tomography (μCT) revealed significant, dose dependent increases in tumor vascularity after ELP-VEGF administration. ELP-VEGF did not induce toxicity in the therapeutic dosing range, and doses one hundred times higher than the expected maximum therapeutic dose were needed to observe any adverse signs in rats. In breast tumor—bearing mice, ELP-VEGF therapy induced a dose-dependent increase in tumor vascularity, demanding caution for potential use in a patient suffering from kidney disease but with known or suspected malignancy.

Highlights

Vascular Endothelial Growth Factor (VEGF), a key mediator of angiogenesis and vascular repair, is reduced in chronic ischemic renal diseases, leading to microvascular rarefaction and deterioration of renal function
In order to extend the half-life of VEGF-A and improve its potential as a therapeutic agent, our lab developed a chimeric protein by fusing human VEGF-A121, a non-heparin binding, freely diffusible isoform[11], to a biopolymer known as elastin-like polypeptide (ELP)[9]
Because the ELP-VEGF fusion protein was designed to be used as a soluble biologic, it was built using an ELP moiety with a T t high enough above body temperature to avoid coacervation and aggregation in vivo, but low enough to allow for induced aggregation under high salt conditions to facilitate its purification by inverse transition cycling

Summary

Introduction

Vascular Endothelial Growth Factor (VEGF), a key mediator of angiogenesis and vascular repair, is reduced in chronic ischemic renal diseases, leading to microvascular rarefaction and deterioration of renal function. We previously showed that ELP-VEGF improves renal vascular density, renal fibrosis, and renal function in swine models of chronic renal diseases. ELP fusion to small proteins or peptides increases plasma half-life[14], reduces immunogenicity[15], and, in the case of therapeutics for renal disease, improves deposition in the kidney after systemic a dministration[16, 17]. The therapeutic effects (improved renal hemodynamics and microvascular integrity, reduced renal injury) were achieved using a single intra-renal dose of 0.1 mg/kg[7, 18] and a systemic intravenous dose of 1.0 mg/ kg[19] These prior studies established the potential of ELP-VEGF for renal therapeutic angiogenesis and defined therapeutic dosing in a range of 0.1–1.0 mg/kg

Methods

Results

Conclusion