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Of Mice and Men

Researchers still don't know whether CYT009-GhrQb is safe and effective. In mice, the vaccine was able to produce high levels of antibodies. Mice on a high-fat diet who were vaccinated gained 15 percent less weight than unvaccinated mice.

Whether the vaccine works on humans is still unknown. Cytos Biotechnology has recruited 112 obese participants who will receive six months of treatment with CYT009-GhrQb followed by six months of careful monitoring. Researchers expect to have preliminary results from the study by late 2006.

Even if the vaccine causes the appropriate immune response, it won't simply melt away the pounds, because it only regulates the desire to eat. People who take the vaccine will still have to be conscious about diet and exercise. But with less of an urge to eat, patients may find it easier to eat smaller portions and stick to a low-fat diet. People who take the drug may need repeated injections until they lose a sufficient amount of weight.

Researchers also don't know whether the vaccine will cause side effects -- the Cytos study will help pinpoint the risks. But some doctors say that using the immune system to modify the body's normal appetite signaling system could be risky and lead to other eating problems.