# Long-Term Tolerability and Safety of AAV5-Id3 Gene Therapy to Eyes

## TL;DR

This study shows that AAV5-Id3 gene therapy is safe and well-tolerated in rabbit eyes over seven months with no harmful effects.

## Contribution

The study demonstrates the long-term safety and tolerability of AAV5-Id3 gene therapy in treating corneal fibrosis in a rabbit model.

## Key findings

- AAV5-Id3 gene therapy caused no significant differences in corneal health compared to control groups.
- Histopathologic and molecular analyses showed normal corneal architecture and gene expression in treated eyes.
- The delivered Id3 gene copies remained stable at 7 months without toxicity.

## Abstract

The inhibitor of
differentiation
3 gene therapy via adeno-associated virus 5 (AAV5-Id3) effectively abrogated corneal fibrosis in vivo. This study examined the long-term tolerability and safety of AAV5-Id3 gene therapy for eyes in vivo using a rabbit model.

Eighteen New Zealand White rabbits, segregated into three groups (naive, AAV5-naked, and AAV5-Id3; n = 6/group), were used. The clinical eye examinations with slit-lamp and multimodal corneal imaging were performed in live rabbits periodically to record the status of ocular and corneal health for up to 7 months. Thereafter, humane euthanasia was performed, and cellular and molecular changes in corneas were studied employing histopathologic, immunofluorescence, and quantitative reverse transcription polymerase chain reaction (RT-PCR) techniques.

Periodic masked eye examinations with slit-lamp, Spectralis, HRT3-RCM, and specular ophthalmic microscopes found no significant differences in the corneas of naive, AAV5-naked, and AAV5-Id3 groups. Modified McDonald–Shadduck scores revealed no signs of blepharospasm, chemosis, abnormal discharge, epiphora, erythema, or epithelial abrasion in three groups. Pachymetry, tonometry, and fluorescein testing detected no alterations in corneal thickness, intraocular pressure, and tear volume in eyes of the three groups. Histopathologic studies revealed corneal architecture, cellular organization, cellular morphology, and collagen levels similar in eyes of the three groups. Quantitative RT-PCR analysis did not find changes in nuclear factor κB, tumor necrosis factor α, α-smooth muscle actin, fibronectin, vascular endothelial growth factor, and pigment epithelium-derived factor messenger RNA levels in three test groups. At 7 months, AAV5-Id3 corneas had 2.73 × 102 ± 0.34 delivered-Id3 gene copies.

Targeted topical AAV5-Id3 gene therapy is tolerable, safe, and nontoxic to the eyes in vivo.

Topical AAV5-Id3 gene therapy treats corneal fibrosis without significant side effects in vivo.