Biological Pathways Involved in Tumor Angiogenesis and Bevacizumab Based Anti-Angiogenic Therapy with Special References to Ovarian Cancer

The creation of new blood vessels from existing ones, which is a mechanism called angiogenesis, is essential in cancer to supply cancerous growth. Moreover, the development and the progression of the tumor and its metastases are the result of an efficient vascular response. Cancer cells release and activate different angiogenic growth factors and their receptors in the tumor microenvironment to promote the angiogenic process. The most important pro-angiogenic factor is the Vascular Endothelial Growth Factor (VEGF) because of its mitogen activity on vascular endothelium. Bevacizumab is a monoclonal antibody that obstructs the binding of circulating vascular endothelial growth factor to its receptors and has been approved for the treatment of primary and recurrent ovarian cancer but also for many other solid tumors.