Obesity: Promising drug but ineffective
The drug MK-0557 was a beacon of hope in the fight against obesity. After ten years of working with the substance, however, a large-scale clinical study has now shown that it only has a minimal effect. While subjects who took the drug for a year lost an average of three pounds more than those who took a placebo, that's not enough to bring the drug to market.
MK-0557 blocks certain receptors in the brain to which the "hunger factor" NPY (neuropeptide Y) normally binds. NPY stimulates the appetite in this way, explains study leader Steven Heymsfield from Merck & Co., Inc. of New Jersey. If NPY can no longer bind to its receptors - especially NPY5R - because MK-0557 occupies the binding site, obese people should develop less appetite and therefore lose weight, so the hypothesis goes. But now the clinical study with 1661 patients showed that this blockade is not sufficient.
This confirms once again that promising candidates can still fail at a late stage of drug development. However, the researchers hope that MK-0557 will eventually produce robust weight loss in combination with other drugs.
