Promising new therapy for cancer
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Cancer therapy could well be revolutionized if the potent antitumour activity of a new molecule works as well in humans as it does in mice. The startling findings in mouse models of cancer were published in a recent issue of *Science* (1999;285:1926-8, [www.sciencemag.org](http://www.sciencemag.org)).

The research builds on the pioneering work of Judah Folkman, a coauthor of the report. He made headlines when he proposed that cancer could be reversed by cutting off the blood vessels that supply tumours and allow them to grow. The growth of new blood vessels (angiogenesis) occurs only in a few physiologic conditions, including tumour growth and pregnancy. Targeting angiogenesis could lead to new therapies that would be effective in all types of cancer. Folkman's research has spawned a huge effort in this direction.

In this experiment, scientists investigated antithrombin, a serine protease inhibitor (or "serpin"), whose usual job in the body is to inhibit clotting enzymes. By making a small change to the molecule, the researchers switched its role to inhibiting angiogenesis and tumour growth. The altered antithrombin acted to reverse angiogenesis and tumours in mice with cancer. The question for future researchers is whether it can do the same thing in humans safely and effectively.