Abstract
Purpose :
Applications of anti-VEGF gene therapy for the treatment of choroidal neovascularization (CNV) are constrained by safety concerns involving chronic suppression of healthy retinal vessels and neurons. Anti-angiogenic therapy against secretogranin III (Scg3) selectively inhibits pathological angiogenesis without affecting healthy vasculatures or neurons and any detectable side effects. The purpose of this study is to test and compare the efficacy of anti-Scg3 and anti-VEGF gene therapy for CNV in mice.
Methods :
Recombinant adenovirus-associated virus (AAV) expressing aflibercept (AAV-aflibercept), anti-Scg3 Fab (AAV-anti-Scg3fab) or mCherry (AAV-mCherry) was constructed and analyzed for binding activity to VEGF and Scg3 by ELISA. AAV was intravitreally injected into C57BL/6J mice on Day 0. Expression of recombinant aflibercept and anti-Scg3 Fab in the retina was detected by Western blot on Day 30. Mice received laser photocoagulation on Day 30 to induce CNV (4 spots/eye). On Day 35, CNV leakage was detected and quantified by fluorescein angiography (FA). Choroids were isolated on Day 37 and stained with Alexa Fluor 488-isolectin B4 (IB4) to label choroidal vessels for CNV quantification.
Results :
Binding activity of aflibercept and anti-Scg3 Fab expressed by AAV was verified by ELISA using immobilized VEGF and Scg3, respectively. AAV-mediated expression of FLAG-tagged aflibercept and anti-Scg3 Fab in mouse retinas was verified by Western blot. AAV-aflibercept and AAV-Scg3fab significantly inhibited CNV leakage intensity (P<0.01 for both AAVs) and area size (P<0.01) with similar efficacies, as quantified by FA. Additionally, both AAVs significantly reduced CNV 3D volume (P<0.05 for aflibercept, P<0.01 for anti-Scg3) and lesion size (P<0.05, P<0.01), as detected by IB4 staining with similar high efficacy. Control AAV-mCherry was without effect on CNV by all measurements.
Conclusions :
Intravitreal administration of AAV-anti-Scg3fab inhibits laser-induced CNV with similar efficacy to AAV-aflibercept. AAV-anti-Scg3fab represents a novel alternative to anti-VEGF gene therapy, including ADVM-022, for wet age-related macular degeneration by providing long-term safety advantages and circumventing frequent intravitreal injections.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.