A Food and Drug Administration (FDA) advisory panel voted to reject Arena Pharmaceuticals’ new diet drug, Lorcaserin, because its showed only modest weight loss results in study participants and raised concerns of possible cancer risk. The FDA isn’t required to follow the recommendations of its advisory committee, however it usually does. A final ruling is expected Oct. 22.
The panel reviewed studies that showed relatively small amounts of weight loss in patients who took the drug. About half of all patients who stayed in the study for one year lost at least 5 percent of their body weight. Comparatively, about a quarter of patients who took a placebo achieved the same result. Patients who took Lorcaserin lost only 3 to 3.7 percent of their body weight beyond what they would have with a placebo, the study showed, not enough to impress the panel.
But more concerning was the possible health risks associated with the drug. Studies show that the Lorcaserin causes cancerous tumors in laboratory rats, but the drug maker insists that the tumors are only specific to rats and that it would not pose the same risks to humans. The drug company failed to assure panel members, who ultimately voted down the recommendation saying that they were unsure if the tumors in rats meant that humans who took the drug would be at greater risk of brain or breast cancers.
Lorcaserin was designed to block appetite signals in the brain much like fenfluramine, a diet drug that was pulled from the market because of cardiovascular safety concerns. Arena says its drug is more selective in the receptors it affects and there has been no evidence of any heart-valve problems associated with Lorcaserin.