Weight-Loss Drug Falls Flat

Diet and exercise still the best prescription for dropping pounds

By Steven Reinberg
HealthDay Reporter

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TUESDAY, Oct. 3 (HealthDay News) -- A once promising weight-loss drug that produced encouraging results in animal studies has failed to deliver in a real-world trial of humans and will be shelved, the pharmaceutical firm Merck & Co. announced Tuesday.

The drug, known as MK-0557, was designed to focus on a "hunger-stimulating factor," which has long been considered a potential target for anti-obesity therapy. And while the drug was well tolerated by the 832 obese people who finished the trial, they only lost an average of 7.5 pounds during the 12-month study, compared with people taking a placebo who lost an average of 4 pounds.

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The report, the culmination of a 10-year study, was published in the October issue of Cell Metabolism.

"People did lose a statistically significant amount of weight, but not clinically meaningful," said lead researcher Dr. Steven B. Heymsfield, executive director of clinical sciences at Merck. "The weight loss was about 3 pounds above the placebo group, but that has no commercial viability for a drug company."

In animal experiments, the drug caused significant weight loss, Heymsfield said. "In humans, the drug also completely blocked the receptor," he said.

In the trial, 1,661 obese people were assigned to MK-0557 or a placebo. Of these, 832 completed the trial.

The upshot of the trial was that a receptor called NPY5R, while related to food intake, appears not to be a key player in regulating hunger. "Maybe it's not a main pathway," Heymsfield said. Another explanation might be that food intake is regulated by a number of pathways. "If one system shuts down, other systems compensate for it," he said.

One expert thinks that hoping for a magic pill is the wrong approach to weight loss.

"In my view, this trial suggests not that a cocktail of drugs will be needed, but that for the most part, drugs are not the right answer at all," said Dr. David L. Katz, an associate professor of public health and director of the Prevention Research Center at Yale University School of Medicine.

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