Abstract
Purpose :
Vascular Endothelial Growth Factor (VEGF) inhibitors are standard therapy for intraocular neovascular disorders such as age-related macular degeneration, leading cause of blindness. However, the relatively short intraocular durability of the current drugs and the burden of multiple intravitreal injections create significant challenges for patients. Our lab has recently described two novel VEGF receptor-1 (VEGFR-1) Fc variants, V1233 and V23, which have high intraocular retention, resulting in longer duration and higher efficacy in mouse models of intraocular neovascularization. Here, we aim to determine the pharmacokinetic properties of these VEGFR-1-Fc variants in rabbits.
Methods :
Recombinant Fc fusion proteins were purified and analyzed for endotoxin levels. 0.5 mg of V1233, V23, aflibercept, and control IgG1 were injected intravitreally in the eyes of New Zealand White rabbits. After 4 hours and 1, 3, 7 and 14 days, serum samples and eyes were collected. The latter were enucleated and immediately frozen. The concentration of the human Fc region in serum and vitreous were determined by ELISA and the distribution of the drugs was measured using immunohistochemistry.
Results :
The recombinant proteins purified in our lab were more than 95% homogeneous, showed very low endotoxin levels (0.08-0.1 EU/mg) and eluted as single monomeric peaks. After 4 h of injection, there were limited amounts of the proteins in the serum of all four groups. At day 1, the serum levels of IgG1 and aflibercept reached 1.5 µg/ml and 0.8 µg/ml respectively. However, the amounts of V1233 and V23 were only 0.023 µg/ml and 0.081 µg/ml, more than 10-fold lower. The levels of V1233 and V23 in serum were extremely low after 14 days. In the vitreous, V1233 and V23 showed higher retention than the IgG and aflibercept groups at day 7. Fourteen days after injection, the amount of V23 in the vitreous was still significantly higher than aflibercept. The distribution of the inhibitors was detectable in all groups after 4 h of injection around the retinal layers. After 14 days, the amount of IgG1 and aflibercept in the retinas was decreased compared to V1233 and V23.
Conclusions :
The VEGFR-1-Fc variants V1233 and V23 have a greater retention in rabbit ocular tissues compared to aflibercept. Overall, these data demonstrate that V1233 and V23 might ensure more sustained and therapeutically relevant interactions for intraocular neovascular disorders.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.