Efficient In-vitro and In-vivo CRISPR RNA Targeting Therapy of HG202 for Macular Degeneration

Abstract

Purpose : Current anti-VEGF agents to treat neovascular age-related macular degeneration (nAMD) require frequent intravitreal injections, resulting in poor patient adherence and increased risk of complications. Furthermore, a significant number of nAMD patients do not respond well to standard anti-VEGF therapy. Here, we developed an RNA-targeting therapy (HG202), a single adeno-associated virus (AAV) vector with high-fidelity CRISPR/Cas13 RNA targeting technology to suppress the expression of VEGFA in the retina, to treat nAMD.

Methods : The choroidal neovascularization (CNV) in mouse eyes was induced by laser photocoagulation. Fundus fluorescein angiography (FFA) and optical coherence tomography (OCT) were performed 7 days after injury followed by immune-stained choroidal flatmounts. We assessed the in vitro and in vivo editing efficiency of HG202, quantified suppression of Vegfa mRNA expression in the retina, and measured the reduction in laser-induced CNV area. We compared the efficacy of HG202 with AAV-anti VEGF and Aflibercept and conducted a toxicity study in NHPs to evaluate the safety of HG202.

Results : Over 40% of Vegfa mRNA expression in the retina of mice (n=8) was suppressed after injecting HG202. The area of laser-induced CNV (87% reduction, P < 0.0001, n = 14) was reduced in mice treated with HG202. Comparatively, the inhibition efficiency of AAV-anti VEGF was 70% reduction (P < 0.01, n = 14) when compared to the vehicle control; Aflibercept showed 47% reduction (P < 0.01, n = 18) when compared to HG202. A single injection of HG202 achieved a durable therapeutic effect for at least 13 weeks in the mouse model. No systemic toxicity and immunotoxicity were observed in NHPs. Moderate fluorescence leakage and retinal structure changes were observed only in the high-dose group (Figure 1). No obvious abnormality of retinal function in all the test animals had been observed.

Conclusions : HG202 successfully blocks VEGFA signaling and achieves long-term transgene expression and RNA editing after a single injection, thus eliminating the need for monthly injections and providing enduring therapeutic benefits. HG202 can potentially offer an effective and long-lasting nAMD treatment for patients who are non-responsive or resistant to anti-VEGF therapy. HG202 as a CRISPR RNA-targeting strategy is currently being investigated in humans.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.