Abstract
Purpose :
Anti-vascular endothelial growth factor (VEGF) treatments such as ranibizumab (RBZ) are currently administered to treat wet AMD via intravitreal (invit) injections, which is unpleasant, expensive and risks complications. We explored the efficacy of topically administered RBZ using an ex vivo pig eye model with cell penetrating peptides (CPPs) to test RBZ penetration and effect on VEGF levels. Ultimately, we aim to create a mathematical model of this interaction.
Methods :
Ex vivo pig eyes were divided into 3 groups and treated with 45ul of 1. topical RBZ+CPP (1mg/ml RBZ & 100mg/ml CPP), 2. invit RBZ+CPP, or 3. invit RBZ (1mg/ml), with invit dH20 for controls. ELISAs measured RBZ and VEGF concentrations in the aqueous (Aq) and vitreous (Vit) at 20min, 40min, 1h & 3.5h (n=3, per group). Two-sample Kolmogorov-Smirnov test was used for statistical analysis.
Results :
In eyes treated with topical RBZ+CPP, the Aq RBZ levels increased significantly, vs controls, by 3.5h (3.45±3.74pg/ml;p=0.03), coincident with a significant (p=0.03) drop in Aq VEGF between 1h (353.94±19.79pg/ml) and 3.5h (25.03±35.40pg/ml). Vit RBZ increased gradually, with significant (p=0.03) increase between 40min (4.25±0.62pg/ml) and 3.5h (17.59±7.45pg/ml), while Vit VEFG remained constant. In eyes treated with invit RBZ+CPP, Aq RBZ was first detected in significant quantities, compared to controls, at 3.5h (126.96±76.53pg/ml;p=0.03), while Aq VEFG remained constant. Vit RBZ increased steadily and significantly (p=0.03) from 20min (62.62±15.16pg/ml) to 3.5h (212.71±1.74pg/ml), coincident with a significant (p=0.03) drop in Vit VEGF from 40min (84.24±54.63pg/ml) to 3.5h (2.00±2.83pg/ml). In eyes treated with invit RBZ alone, Aq RBZ was present in significant quantities, vs controls, by 1h (37.41±36.75pg/ml;p=0.03), while Aq VEFG remained constant. Vit RBZ maintained constant values (~200pg/ml) for all time points, while Vit VEGF was undetectable from 40min onwards.
Conclusions :
Our CPP allows topical RBZ to penetrate the cornea. But, our CPP reduces RBZ availability and efficacy in neutralising VEGF for invit treatment. Invit RBZ treatments result in higher Vit RBZ levels with more rapid and complete reduction of Vit VEGF than topical treatment. Mathematical modelling will be used to further explain the mechanistic underpinnings of the experimental data and will use these data to predict RBZ, VEGF and CPP dynamics in human eyes.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.