Sept. 16, 2010 -- An FDA advisory panel rejected the latest weight loss drug to make a bid for the U.S. market.
The panel of experts voted 9 to 5 to urge the FDA not to approve lorcaserin. The drug -- know by the brand name Lorqess, is made by Arena Pharmaceuticals.
The FDA doesn't have to follow the panel's recommendation, but it usually does. The vote is the latest blow to the drug industry's effort to develop safe and effective weight loss drugs.
Only two prescription drugs are approved for weight loss in the U.S. One of them, Meridia, also known as sibutramine, split the panel on Wednesday on the question of whether it should be pulled off the U.S. market because of safety concerns.
In the case of lorcaserin, the panel ruled that the modest weight loss delivered by the drug in clinical studies did not make up for several unanswered questions about its safety. In particular, panelists said they were troubled by evidence the drug increased the risk of breast tumors in laboratory animals.
Meanwhile, most patients who took lorcaserin lost relatively small amounts of weight. About half of all patients who stayed in company studies for one year lost at least 5% of their body weight. At the same time, about a quarter of patients who took a placebo achieved the same result.
In all, patients taking the drug lost only between 3% and 3.7% of their body weight beyond what they would have with a placebo, the study showed. That fell short of the FDA's criteria for an effective weight loss drug.
The company argued that even small amounts of weight loss can have positive health effects for overweight and obese adults. But experts said they were troubled that Arena's study excluded patients with diabetes and cardiovascular disease, groups that make up a large proportion of the patients who would receive the drug.
"Face it ,the people who need this have diabetes, have high blood pressure" and high cholesterol, said Lamont G. Weide, MD, PhD, a professor of medicine and diabetes expert at the University of Missouri, Kansas City and a member of the panel.
Panel chairman Abraham Thomas, MD, who voted to approve the drug, said excluding such sicker patients was problematic. "In the real world ... the achievable results are never as good as in the clinical trial," said Thomas, who chairs the department of endocrinology at the Henry Ford Hospital in Detroit.
Panelists also said they wanted to see more research on lorcaserin's possible links to cancer. The drug caused a sevenfold increase in mammary tumors in laboratory rats. While the doses were far higher than human doses, experts said they were uncomfortable not knowing how to translate the findings to the human population.
In a statement, Arena president and CEO Jack Lief said the company and partner company Eisai believe the benefits of lorcaserin outweigh the risks. "Arena will work closely with the FDA as the agency completes its review of the lorcaserin new drug application," the statement said.
The company said it is currently studying the drug in roughly 600 diabetes patients. Experts said they are eagerly awaiting the results, acknowledging that so few effective prescription weight loss drugs are available to patients now.
"I think the drug is promising, it's just not quite there yet," said Edward W. Gregg, MD, chief of the Epidemiology and Statistics Branch at the CDC and a member of the panel.