Angiogenesis inhibitors in cancer therapy.

The formation of new blood vessels is essential for tumor growth and progression. Angiogenesis inhibitors have been demonstrated to block tumor growth and/or metastasis. Although initial clinical data have been disappointing, new strategies to increase the efficacy of these drugs have ensured their ongoing clinical development. This review highlights the broad spectrum of angiogenesis inhibitors under investigation in both preclinical and clinical studies. From 'natural' inhibitors to thalidomide analogs, the number of compounds in development is extensive. Elucidating the mechanisms of action will enable their use in conjunction with existing/other novel therapies, thereby maximizing the potential efficacy of angiogenesis inhibitors to fulfill their promise in patients with cancer.