Abstract
Purpose :
In a previous study, use of AAV codon-optimized IDUA (optIDUA) by a single corneal intrastromal injection (CII) in naturally occurring MPS1 dogs completely cleared corneal storage disease. Herein, we evaluated the chronic ocular toxicity, tolerability, and ocular inflammation associated with CII of saline, AAVcapsid, or AAVoptIDUA in rabbits.
Methods :
CII in normal NZW rabbits of 50 uL of saline (n=6), AAV-IDUAe9 (n=8), or AAV-IDUAe10 (n=8) was performed using a 31 g needlle. Ocular inflammation, central corneal thickness (CCT) and intraocular pressure (IOP) measurements were taken on days 0, 1-5, 7, then weekly until 6 months when the rabbits were euthanized and eyes collected and analyzed for transgene immunofluorescence or probe-based qPCR analysis. To correlate the therapeutic phenotype to transgene expression in ocular tissue, RNA was recovered from conjunctiva, cornea, iris/ciliary body, and retina/choroid from CII eyes and opposite uninjected eyes. Serum neutralizing antibody (NAB) to vector capsid was analyzed. Viral genome (vg) biodistribution was assessed by qPCR in peripheral body tissues.
Results :
Corneal opacity nearly resolved by 2 hours after CII and was clear by 24 hours. Mild elevation of HM scores was observed 24 hours after injection but returned to baseline by day 7 and no abnormalities were noted through 6 months after CII. Endothelial counts were normal in each group and not significantly different. Vg were detected by qPCR in the cornea but not in other tissues of the eye while non-injected eyes and peripheral tissues were negative. IDUA transcript was detected in corneas of injected rabbits as confirmed by qPCR but not detected in the ciliary body/iris or retina of all rabbits. Only one rabbit had a NAB titer (1:2) to the AAV8 capsid but no NAB was in the aqueous or vitreous humor of eyes injected with saline, IDUAe9, or IDUAe10.
Conclusions :
This study determined that both the lowest administered efficacious AAVoptIDUA dose used in MPS1 dogs and a 10-fold higher dose resulted in no immunologic response or viral genome distribution to off target tissues in NZW rabbits. This study, combined with our previous studies in MPS1 dogs, suggests that this innovative therapeutic approach of CII AAV-IDUA has a very high potential to prevent blindness in MPS1 patients receiving therapy in a safe and effective manner.
This is a 2020 ARVO Annual Meeting abstract.