Suprachoroidal AAV8-Vectored Gene Transfer Provides Widespread Transgene Expression in RPE and Retina

Abstract

Purpose : To investigate the potential value of suprachoroidal injection of AAV8 vectors for ocular gene transfer

Methods : Suprachoroidal or subretinal injection of 2.85 x10¹⁰ gene copies (GC) of AAV8.GFP or RGX-314 (AAV8.antiVEGFfab) was done in Norway Brown rats (n=40) and suprachoroidal injection of 4.75 x10¹¹ GC of AAV8.GFP was done in Rhesus macaques (n=3). Retina and RPE/choroid flat mounts or ocular sections were examined by fluorescence microscopy. GFP protein, antiVEGFfab and albumin levels to evaluate vascular leakage were measured by ELISA. At 2 or 7 weeks after suprachroidal or subretinal injection of RGX-314, an intravitreous injection of VEGF165 given to induce leakage and after 24 hours vitreous albumin was measured.

Results : Two weeks after a single suprachoroidal injection of AAV8.GFP in rats, there was strong GFP fluorescence covering 23% of RPE/choroid flat mounts. Ocular sections showed GFP fluorescence around the entire circumference of the equator of the eye throughout the choroid, RPE, and all layers of the retina. Two suprachoroidal injections of AAV8.GFP in the same eye resulted in GFP fluorescence covering 42% of the area of RPE/choroid flat mounts. VEGF-induced increase in vitreous albumin was significantly and similarly reduced 2 or 7 weeks after suprachoroidal or subretinal injection of RGX-314. AntiVEGFfab transgene protein levels were equally high for the surpachoroidal and subretinal route. Three weeks after a single suprachoroidal injection of AAV8.GFP in NHPs, there was strong expression of GFP throughout approximately 1/3 of the retina and RPE/choroid.

Conclusions : Widespread transduction of all layers of the retina and suppression of VEGF-induced vascular leakage indicate that suprachoroidal delivery has the potential to provide similar results to subretinal delivery and should be further explored for AAV8-vectored ocular gene transfer.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.