Cancer drug may double as fat-busting treatment for obesity

Way back in 2002, Dr. Judah Folkman hit upon a tantalizing weight-loss strategy for obese mice. When given daily injections of a drug designed to fight cancer, their fat melted away. The higer the dose they got, the more fat they lost. Some of the obese mice shed so much weight that they wound up at “near normal body weights,” Folkman and his colleagues reported in this article in Proceedings of the National Academy of Sciences.

Whatever happened to this promising fat-busting drug? Not much -- at least in terms of fighting obesity.

Folkman focused most of his attention on developing drugs to destroy cancer tumors. The drugs, known as angiogenesis inhibitors, worked by cutting off the blood supply to tumors. Without blood vessels to bring in fresh oxygen and nutrients, the tumors couldn’t survive. Avastin is one example of a cancer drug that works this way.

But tumors aren’t the only tissues in the body that need their own blood supply to grow. So does fat. So a group of doctors and researchers from the University of Mississippi Medical Center in Jackson decided to follow up on Folkman’s experiment.

Dr. Jian-Wei Gu, who studies cancer and how it is influenced by obesity, led the research team. They used an angiogenesis inhibitor called Sunitinib, which is normally used to treat kidney and gastrointestinal tumors.

Some of the obese mice were fed Sunitinib daily for two weeks. Other mice received injections of the drug over the same period of time. Another group of obese mice wasn’t treated with the drug at all. They served as the controls.

When the two weeks were over, the mice who got the drug had slimmed down substantially -- on average, 70% of their fat mass was gone. It didn’t matter whether they received the drug orally or got a shot. Meanwhile, their lean body mass remained the same. The cancer drug was targeting the fat but leaving other crucial tissues alone.

Gu and his colleagues noticed another change in the treated mice. When the treatment was over, these slimmed-down mice ate less of their chow. With less fat in their bodies, Gu theorized, they produced fewer of the hormones that signal the brain to eat. Gu and his colleagues presented their findings Tuesday at the Experimental Biology 2013 conference in Boston.

In a statement released by the American Physiological Society, a co-sponsor of the conference, the research team emphasized that their results were preliminary and not ready to be applied to the one-in-three American adults who are obese today. At a minimum, they want to test the drug on other types of obese mice as well.

Even if Sunitinib -- and medications like it -- turns out to be an effective fat fighter in people, that doesn’t mean it’s a silver bullet for the nation’s obesity crisis. Proteins involved in growing new blood vessels play many roles in the body, and the drug might cause some sort of “off-target effects” that weren’t apparent in the mice, the researchers warned. Still, they are clearly hopeful about the possibilities.

“This could be a very good strategy for treating obesity, at least in the short term,” Gu said in the statement.

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