Combretastatin A-4 phosphate suppresses development and induces regression of choroidal neovascularization.
Combretastatin A-4 (CA-4) is a naturally occurring agent that binds tubulin and causes necrosis and shrinkage of tumors by damaging their blood vessels. In this study the effect of a CA-4 prodrug, combretastatin A-4-phosphate (CA-4-P), was tested in two models of ocular neovascularization. The effect of CA-4-P was quantitatively assessed in transgenic mice with overexpression of vascular endothelial growth factor in the retina (rho/VEGF mice) and mice with choroidal neovascularization (CNV) due to laser-induced rupture of Bruch's membrane. In rho/VEGF mice, daily intraperitoneal injections of 4.0 mg/kg CA-4-P starting at postnatal day (P)7, the time of onset of transgene expression, resulted in a significant reduction in the number of neovascular lesions and total area of neovascularization per retina at P21, compared with vehicle-injected mice. In mice with laser-induced rupture of Bruch's membrane, daily intraperitoneal injections of 75 or 100 mg/kg CA-4-P resulted in a significant reduction in the area of CNV at rupture sites compared with vehicle-injected mice. In mice with established CNV, daily intraperitoneal injections of 100 mg/kg CA-4-P for 1 week resulted in a significant reduction in CNV area at rupture sites compared with the baseline area before treatment or the area of CNV in vehicle-treated mice. These data indicate that CA-4-P suppresses the development of VEGF-induced neovascularization in the retina and both blocks development and promotes regression of CNV. Therefore, CA-4-P shows potential for both prevention and treatment of ocular neovascularization.