ETA Receptor Blockade With Atrasentan Prevents Hypertension With the Multitargeted Tyrosine Kinase Inhibitor ABT-869 in Telemetry-instrumented Rats

ABT-869 is a novel multitargeted inhibitor of vascular endothelial growth factor and platelet-derived growth factor receptor tyrosine kinases (RTKs) with potent antiangiogenic properties that slow tumor progression. Vascular endothelial growth factor receptor blockade has been shown to produce hypertension. Atrasentan is a potent and selective endothelin (ETA) receptor antagonist that lowers blood pressure and affects tumor growth. To assess the utility of ET,, receptor blockade in controlling hypertension with RTK inhibition, we evaluated the ability of atrasentan to block hypertension with ABT-869 in conscious, telemetry-instrumented rats. Changes in mean arterial pressure (MAP) and heart rate (HR) were evaluated using mean values and the area under the curve (AUC). Atrasentan (0.5, 1.5, and 5.0 mg kg (1) d (1) for 5 days) elicited dose-dependent decreases in MAP-AUC (-16.7 +/- 1.3, -20.94 +/- 3.68, and -30.12 +/- 3.57 mm Hg-day, respectively) compared with vehicle. ABT-869 (1, 3, 10, 30 mg kg (1) d (1) for 5 days) increased MAP compared with vehicle (MAP-AUC values of -5.52 +/- 3.75, 12.7 +/- 9.4, 37.5 +/- 4.4, and 63.8 +/- 3.3 mm Hg.day, respectively). Pretreatment with atrasentan (5 mg/kg for 5 days) prevented and abolished the hypertensive effects of ABT-869. Thus, ETA receptor blockade effectively alleviated hypertension with RTK inhibition and may serve a dual therapeutic role by preventing hypertension and slowing tumor progression.