Development of new drugs in angiogenesis

Angiogenesis, the growth of new capillaries from pre-existing vessels, contributes to the development and progression of a variety of physio-pathological conditions. There is growing evidence that anti-angiogenic drugs will improve future therapies of diseases like cancer, rheumatoid arthritis and ocular neovascularisation. Conversely, therapeutic angiogenesis is an important homeostatic response contributing to limit the damage to ischemic tissues. Molecular processes involved in angiogenesis include stimulation of endothelial growth by cytokine production (i.e. vascular endothelial growth factor, VEGF; fibroblast growth factor-2, FGF-2), degradation of extracellular matrix proteins by matrix metalloproteinases (MMPs), and migration of endothelial cells mediated by integrins (cell membrane adhesion molecules). Drugs targeting pathologic angiogenesis have been designed to interfere with any of these steps and are currently undergoing evaluation in early clinical studies. Important therapeutic strategies are: suppression of activity and signaling pathways activated by the major angiogenic regulators like VEGF and FGF-2; inhibition of function of alphav-integrins and MMPs; exploitation of endogenous anti-angiogenic molecules like angiostatin and endostatin. The strategy to "silence" endothelium with antiangiogenic drugs to starve tumors, provides a novel approach for cancer treatment. The unique targets of these drugs (endothelium) make them distinct from traditional cytotoxic chemotherapeutic agents. Conversely, gene transfer of angiogenesis inducers is the new approach for therapeutic neovascularization, which is under investigation using a variety of growth factors and a wide array of potential delivery systems, including the application of the gene as naked DNA or by viral vector. The status of pro- and anti-angiogenic therapies is here presented and discussed.