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IF YOU want to stop a leak in your kitchen, would you cut off the water
supply to the whole neighbourhood? Probably not. Yet that鈥檚 the kind of approach
being tried with experimental anti-cancer drugs that block the growth of blood
vessels.

These drugs prevent 鈥渁ngiogenesis鈥� throughout the body, not just in tumours.
But now Napoleone Ferrara and his team at Genentech in California have found a
protein that promotes angiogenesis only in hormone-producing glands. Although
the protein promotes rather than inhibits angiogenesis, the discovery is causing
excitement because it suggests there may be ways to block blood-vessel growth in
specific tissues that have become cancerous.

The body might respond better to such drugs, says Peter Carmeliet of the
University of Leuven in Belgium. It may also be possible to find a
cardiac-specific factor to boost angiogenesis in people with heart disease.
鈥淭his is a new way of thinking in angiogenesis,鈥� he says. 鈥淭here are some clear
therapeutic implications.鈥�

Ferrara鈥檚 team fished the protein out of a 鈥渓ibrary鈥� of proteins at
Genentech. The researchers injected it in several locations in mice, but found
it had no effect. But when they injected it into the ovaries, which are
endocrine glands, the protein caused extensive growth of blood vessels.

The team has dubbed it EG-VEGF, or endocrine gland vascular endothelial
growth factor. It鈥檚 the first tissue-specific angiogenesis factor. 鈥淚t is
unique,鈥� says Ferrara.

But the effectiveness of treating cancer with anti-angiogenic drugs remains
to be proven. The results of several trials of existing, non-specific drugs have
been disappointing.