Cancer angiogenesis: targeting the heel of Achilles

Angiogenesis, which usually heralds a poor prognosis for patients, is essential for malignancy. However, this same process is useful in providing a direct and systemic route for the delivery of cytotoxics to the actively growing parts of the tumour. In fact, there is even some merit to stabilising (normalising) the tumour vasculature to aid drug delivery to the deeper recesses of a growing tumour. Additionally, natural biological inhibitors of angiogenesis such as pigment epithelium-derived factor (PEDF) are being developed to test whether they have better activity than older ones such as endostatin. The field of cancer angiogenesis, more than 35 years old now, has seen a few drugs reaching the market, such as Avastin. However, there have been a multitude of failed ones, due to lack of activity, especially when tested in vivo and some failing at clinical trials. This review looks at the current state of play in the area of cancer angiogenesis, and development of therapies to target it.