Receptor tyrosine kinase inhibitors AG013764 and AG013711 reduce choroidal neovascularization in rat eye

Abstract

Age-related macular degeneration (AMD) is the major cause of blindness for people over 60. In the "wet" form of AMD compounds targeting growth factor signaling pathways such as VEGF have been a major focus for therapeutic interventions. In a previously developed rat model of CNV, we utilized two receptor tyrosine kinase inhibitors (RTKi) to block VEGFR-1, VEGFR-2 and PDGFR signaling following the establishment of CNV. AAV-VEGF 165 was injected into the subretinal space of rats at postnatal days 15-17. Six weeks later, a suspension of RTK inhibitors, AG013764 or AG013711, was injected intraperitoneally (IP, twice daily) or intravitreally (every five days) over a two week period. FITC-dextran whole-mounts of RPE-choroid-sclera were prepared after the animals were sacrificed. CNV area was quantified using Neurolucida to measure the hyperfluorescence on FITC-dextran whole-mounts. Histology and immunohistochemistry were performed as described previously. VEGF expression in control and treated eyes was confirmed by immunohistochemistry and histological sections indicated recovery of retinal morphology and CNV reduction in treated eyes. In the animals IP injected with AG013764 or AG013711 the mean CNV level was reduced by 25 to 33% compared to control, but this effect did not achieve statistical significance. Intravitreal injections of AG013764 or AG013711 reduced the level of CNV by approximately 60% compared to control (p< 0.005 or p< 0.05, respectively). These data show that two RTK inhibitors, AG013764 or AG013711, delivered intravitreally, significantly reduce blood vessel proliferation in this AAV-VEGF 165 model of CNV.

Improved assessment of laser-induced choroidal neovascularization

“…Recently published methods include describing CNV staining on FA relative to the size of optic nerve head (Sickenberg et al, 1999), by measuring diameter of CNV lesion along an axis (Criswell et al, 2008), by assessing lesion size based on the presence or absence of leakage (Dobi et al, 1989; Husain et al, 1999; Kanai et al, 2000; Obana et al, 2000; Tobe et al, 1998; Zacks et al, 2002), by using a qualitative grading method (Nishiwaki et al, 2002; Qu et al, 2009;Wang et al, 2007), and by measuring the CNV staining perimeter using imaging software (Funakoshi et al, 2006). None of these methods have been validated and many of them are arguably unable to detect small, but significant, changes in CNV lesion size due to their subjective and categorical (mild, moderate, severe) nature.…”

“…However, results vary considerably depending on which technique is used to quantify the CNV lesions, making it difficult to compare results among the above referenced studies. For instance, some methods are unable to detect small, but significant, changes in CNV lesions due to their subjective and categorical nature, such as classifying lesions as mild, moderate, severe or based on the presence or absence of leakage (Dobi et al, 1989; Husain et al, 1999; Kanai et al, 2000; Nishiwaki et al, 2002; Obana et al, 2000; Qu et al, 2009; Tobe et al, 1998; Wang et al, 2007; Zacks et al, 2002). Therefore, the purpose of this study is to develop new and compare existing methods of analyzing laser-induced CNV, on both choroidal mounts and FAs, to determine their validity and reliability in order to make recommendations that may improve the consistency of CNV reporting.…”

Horizons in Therapy for Corneal Angiogenesis

“…Therefore, inhibitors targeting both VEGFR and PDGFR can contribute to the regression of actively proliferating endothelial cells in multiple models of ocular neovascularization. 34 Midostaurin (PKC412) is an orally administered small multikinase tyrosine inhibitor that binds to the intracellular enzymatically active domain of VEGFR, PDGF, and stem cell factor and prevents phosphorylation and activation of the VEGF cascade. It was shown to inhibit choroidal neovascularization.…”

Reversal of Retinal Vascular Changes Associated with Ocular Neovascularization by Small Molecules: Progress toward Identifying Molecular Targets for Therapeutic Intervention

“…Previous data have shown that Sub-Tenon administration of AG-013958 (Pfizer, Inc.) in 21 patients with subfoveal CNV associated with AMD resulted in minimal levels of systemic exposure, which was similar to levels found in 13 cynomolgus monkeys dosed with the same compound [51]. Several studies have indicated that intravitreal injections of AG013764 or AG013711 reduced the level of CNV by approximately 60% compared to control [52].…”