[Angiogenesis inhibitors in advanced cancer. Many current clinical trials show promising results]

Tumour growth and metastasis are dependent on angiogenesis, the formation of new blood vessels. In experimental models, tumour regression can be induced by the administration of specific angiostatic agents. The inhibition of angiogenesis represents a new approach in cancer therapy. Specific inhibition of angiogenesis is not characterised by the typical dose-limiting toxicity of chemotherapy. By targeting the untransformed and genetically stable vascular endothelium, drug delivery is no problem, and angiostatic therapy is not associated with the development of drug resistance. However, the treatment has to be continued for months or years, and some angiostatic agents are known to interfere with fertility. Approximately thirty angiostatic agents are undergoing clinical trials, and another fifty agents preclinical testing. Since the clinical trials are performed on patients with advanced tumours intractable to conventional therapy, and as the test drugs are first generation angiostatic agents, their effect is measured in terms of delay in tumour progression or reduction in values for surrogate endpoints such as tumour markers. In this article, based on reports presented at a recent international conference on angiogenesis antagonists, a few angiostatic agents are reviewed with brief comments on their performance in early clinical trials, and some new and promising angiostatic strategies are outlined.