Progress report on the potential of angiogenesis inhibitors for neuro-oncology.

New therapies for brain tumors are urgently needed. Brain tumors are highly vascularized, supporting the potential of anti-angiogenic therapies in their treatment. The promise of blocking tumor growth through inhibiting new blood vessel formation with anti-angiogenic agents has been heralded as a therapeutic breakthrough, and pre-clinical data supported this enthusiasm. However, early clinical trials in humans have been somewhat disappointing. Nonetheless, great optimism for these agents remains, and many new anti-angiogenic agents and strategies are being evaluated pre-clinically and in clinical trials. A number of issues need to be considered in the application of these agents to neuro-oncology. In this review, we discuss the biology of blood vessel formation in the brain and brain tumors as it relates to anti-angiogenic therapies. The difficulties inherent in performing clinical trials of anti-angiogenic therapies in patients with brain tumors are outlined. Finally, we consider numerous individual antiangiogenic and antivascular therapies now in pre-clinical testing or in clinical trials.