Effects of an ALK-1 kinase inhibitor on ocular leakage and neovascularization in rats

Abstract

Purpose : To characterize BAY-754, a novel kinase inhibitor targeting activin-like kinase 1 (ALK-1), and describe its efficacy on ocular neovascularization in the rat laser-induced choroidal neovascularization (CNV) model when administered topically.

Methods : The kinase profile of BAY-754 was characterized, and the biochemical and cellular potency on ALK-1 were determined using novel in vitro assays. Different doses of BAY-754 administered topically (10 µL BID) in early and delayed treatment regimens were tested regarding the reduction of vascular leakage and neovascularization in the rat laser CNV model. Concentrations of BAY-754 were measured in plasma and different eye compartments.

Results : BAY-754 was characterized as a kinase inhibitor with a rather specific profile, mainly targeting ALK-1 (IC50 1.6 nM biochemical, 10 nM cellular) and in particular with very low activity vs. VEGFR2 (IC50 4.4 mM biochemical, >1 mM cellular). In the rat laser CNV model, BAY-754 showed dose-dependent inhibition of vascular leakage and neovascularization when administered as eye drops. The mean angiography score in the control group was 1.75±0.19 (all data presented as mean±SD; n=22) and was significantly reduced to 1.47±0.11, 1.43±0.15, 1.41±0.13 and 1.31±0.17 by BAY-754 at 2.5 (n=7), 5 (n=7), 10 (n=7) and 20 mg/mL (n=29), respectively (F=22.12, p<0.001; post hoc tests p<0.05). The area of choroidal neovascularization was likewise reduced from 84429±9092 μm² (n=23) in untreated rats to 59781±9595 μm², 54805±10290 μm², 56458±10746 µm² and 58972±9639 μm² compared to rats dosed with 2.5 (n=7), 5 (n=7), 10 (n=8) and 20 mg/mL (n=29), respectively (F=29.88, p<0.001; post hoc tests p<0.05). BAY-754 at 20 mg/mL also significantly reduced vascular leakage (controls 1.79±0.15, n=17, treated 1.41±0.17, n=26; p<0.001) and neovascular area (controls 86755±9515 μm², n=17, treated 68641±12769 μm², n=26; p<0.001) on day 21 when treatment start was delayed to 7 days after laser injury. For a topical dose of 20 mg/mL, Cmax of BAY-754 at the back of the eye was 4.9 mg/L with AUC(0-24) back of the eye being 17 mg●h/L. Systemic exposure was very low.

Conclusions : Here, we characterized an ALK-1 inhibitor in vitro and generated first evidence of back of the eye exposure and efficacy in a rat model of neovascular AMD when administered topically as eye drops.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.