Abstract
Purpose:
Vascular endothelial growth factor (VEGF) antagonists (Ranibizumab, Aflibercept and Bevacizumab) are currently the therapy of choice for neovascular age-related macular degeneration (AMD). It has been proposed that Bevacizumab accumulates in RPE cells in contrast to Ranibizumab, while there is up to date no published data regarding Aflibercept. In the presented study we compare the effects of all three VEGF antagonists regarding their respective uptake in human RPE cells over time.
Methods:
Human RPE cells (ARPE-19) were cultured for 4 weeks on laminin-coated transwell inserts using reduced-serum medium until they formed a confluent monolayer and reached a transepithelial resistance of 35 Ω/cm2. Then they were treated with clinical doses of Cy5-labeled Ranibizumab, Aflibercept or Bevacizumab for 1h after which the drug-free reduced-serum medium was applied once again. After 0h, 12h, 24h and 72h the cells were fixed, stained with the early endosome marker Rab5 (Alexa488) and nuclei counterstained with 4',6-diamidino-2-phenylindole (DAPI). Uptake of the respective drug was assessed with conventional fluorescence, confocal fluorescence and two-photon microscopy by measuring co-localized spots of Cy5 and Alexa488.
Results:
At clinical significant doses, Ranibizumab (0.125 mg/ml), Aflibercept (0.5 mg/ml) and Bevacizumab (0.25 mg/ml), were all detectable in the RPE cells. Initially Aflibercept showed the fastest uptake with no significant decrease within 72h. Interestingly Ranibizumab had the second fastest uptake, but declined significantly during the observation period. Bevacizumab had the slowest uptake of all three drugs, but like Aflibercept had no significant reduction over 3 days.
Conclusions:
On the one hand Aflibercept and Bevacizumab in the administered clinical doses endure in RPE cells considerably longer than Ranibizumab, which might lead to accumulation-related (side)effects on RPE cell function and the clinical course of AMD. On the other hand Ranibizumab seems to be eliminated noticeably faster than the other two VEGF antagonists, which probably has an influence on the efficacy of the drug and the duration of the retreatment interval.
Keywords: 701 retinal pigment epithelium •
748 vascular endothelial growth factor •
412 age-related macular degeneration