Creating a weight loss drug for commercial use wasn't the University of Texas MD Anderson Cancer Center researchers' ultimate goal. What they are really looking to see is if getting rid of excess fat in obese prostate cancer patients makes their cancer better than without weight treatment. But, the effectiveness of the weight loss drug in the monkeys they first tested it on may mean it could see the commercial market once human testing is approved and complete.
"Obesity is a major risk factor for developing cancer, roughly the equivalent of tobacco use, and both are potentially reversible" said co-senior author Wadih Arap, M.D., Ph.D., in a press release. "Obese cancer patients do worse in surgery, with radiation or on chemotherapy -- worse by any measure."
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Although the researchers call the drug "fail proof" -- meaning it has worked in each monkey that they've given it to -- they do acknowledge that when the monkey stops taking the drug, the weight comes back on. This bounce back they attribute to them monkeys going back to eating excessive amounts of food.
As a whole the drug works by targeting the blood vessels that keep fat cells alive. According to the press release, killing the blood cells means the fat cells get reabsorbed and metabolized. On average, the monkeys lost about 11 percent of their body weight.
The rhesus monkeys in the current study were "spontaneously" obese, said study first author Kirstin Barnhart, D.V.M, Ph.D., a veterinary clinical pathologist at MD Anderson's Keeling Center for Comparative Medicine and Research in Bastrop, Texas. No specific actions were taken to make them overweight; they became so by overeating the same foods provided to other monkeys in the colony and avoiding physical activity.
According to the researchers, this primate model is similar to human obesity with factors in common such as metabolic syndrome, characterized by an increased resistance to insulin, which can lead to the development of type 2 diabetes and cardiovascular disease. Monkeys treated with the drug called Adipotide showed marked improvements in insulin resistance -- using about 50 percent less insulin after treatment.
Monkeys in the studies remained bright and alert throughout, interacting with caretakers and demonstrating no signs of nausea or food avoidance, according to the release. This is a potentially important finding since unpleasant side-effects have limited the use of approved drugs that reduce fat absorption in the intestines.