Study sheds light on angiogenesis inhibitors, points to limitations,...( A new generation of cancer drugs des...),Health

A new generation of cancer drugs designed to starve tumors of their blood supply called "angiogenesis inhibitors"succeeds at first, but then promotes more invasive cancer growthsometimes with a higher incidence of metastases, according to a new study in animals. The research clarifies similar findings in other animal studies and is consistent with some early evidence from a small number of clinical trials with cancer patients.

"People have thought that angiogenesis-inhibiting therapy should hinder metastasis, but these studies show this is not necessarily the case," says Gabriele Bergers, PhD, co-author of a paper reporting the study in the March 3, 2009 issue of the journal Cancer Cell. Bergers is an associate professor of neurosurgery and anatomy at the University of California, San Francisco (UCSF).

The scientists urge new studies to determine if the drugs affect tumors in patients as they do in their mouse models of human cancers. They call for preclinical and clinical trials combining angiogenesis-inhibiting drugs with ones targeting the capability for invasion and metastasis. Some treatment strategies already in clinical trials that pair angiogenesis inhibitor drugs with chemotherapy, for example, might gain the first drug's early benefit without triggering subsequent invasion or metastasis, they note.

"The ability of angiogenesis inhibitors to starve tumors rather than poison them has been a true breakthrough," says Douglas Hanahan, PhD, professor of biochemistry and biophysics at UCSF and co-senior author on the paper. "But they are not likely to be a one-stop fix. No cancer drug has yet been found to cure most forms of human cancer. Therapies beat it back, but almost inevitably the cancer develops some form of resistance."

Hanahan and Bergers are both scientists at the UCSF Helen Diller Family Comprehensive Cancer Center.

The other co-senior author of the paper is Oriol Casanovas, PhD , a group lead
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