Combined Effect of Anti-Angiogentic Agents, Angiotensin Type 1 Receptor Antagonists and Radiation Therapy

Solid tumors require angiogenesis for their growth and to form metastatsis. Many new cancer therapies are directed against tumor vessels. Radiation therapy is one of the most widely used treatments for a wide variety of tumors, and is thought to act by directly targeting clongenes, as well as was induce apoptosis of endothelial cells, and reduce angiogenesis. Vascular targeting agents are aimed specifically at the existing tumor vasculature. Anti-angiogenic agents target angiogenesis or new growth of tumor vessels. Recent preclinical studies have suggested that radiotherapy in combination with antiangiogenic agents enhances the therapeutic ratio of ioninzing radiation alone. Targeting tumor vasculature has strong biological rationale in radiation therapy and preclinical studies consistently show an increase in radiationsensitization with combined treatment. This review article explores the complex interaction between radiation therapy and antiangiogenic agents. Furthermore we discuss the efficacy of combined radiotherapy and AT1-R antagonist (TCV-116) on tumor associated angiogenesis.