Abstract
Purpose :
To evaluate the safety and tolerability of intracameral recombinant AAV as a gene therapy vector in nonhuman primates. The anterior segment is an attractive target for genetic intervention due to its accessibility, relative immune privilege, and ease of monitoring through aqueous sampling, and in vivo imaging techniques. We demonstrate that intracameral delivery of AAV9 vector is well tolerated and has a unique transduction profile in the nonhuman primate.
Methods :
In an initial experiment, 8 primate eyes were intracamerally injected with 50 ml of 5E11 vg or 9E11 vg (vector genomes) of AAV9-expressing eGFP. In a second experiment, 7 primate eyes were intracamerally injected with 50 ml of 5E12 vg of AAV9 encoding a secreted protein. At 2-week intervals for 4 months, ophthalmic examinations were performed using specular microscopy, pachymetry, tonometry, slit lamp biomicroscopy, anterior segment imaging, and anterior segment OCT. Clinical observations were performed routinely. Serum and aqueous samples were also collected as part of routine examinations. Immunohistochemistry (IHC) was performed on the anterior chamber of the eye at study termination.
Results :
Intraocular pressure was maintained within normal ranges at all timepoints following treatment. Corneal thickness, endothelial cell area and cell density measurements were not significantly different at any time point between AAV9 vector and vehicle injected eyes. No significant change in body weight or food consumption was observed. No evidence of increased inflammation was detected compared to contralateral vehicle control eyes. IHC revealed an open iridocorneal angle and no evidence of inflammation or cellular damage. Eyes injected with AAV encoding GFP revealed efficient transduction of the corneal endothelium, and eyes injected with AAV encoding a soluble secreted protein demonstrated high aqueous levels by ELISA.
Conclusions :
We have observed sufficient tolerability of the anterior chamber to intracamerally delivered AAV vector in the nonhuman primate. This study did not reveal clinical signs indicative of localised or systemic side effects. Transduction was found unique to the corneal. This pre-clinical data demonstrates the potential of genetic intervention in the corneal endothelium of the anterior chamber to treat corneal diseases or to generate a “protein factory” for the treatment of other anterior segment conditions such as glaucoma.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.