A US Food and Drug Administration (FDA) advisory committee has voted against recommending federal approval of the new obesity drug lorcaserin, made by Arena Pharmaceuticals Inc under the brand name Lorqess, making it the third time this year that an obesity drug has failed to get the thumbs up from the panel.
On Thursday, the FDA Endocrinologic and Metabolic Drugs Advisory Committee voted 9 to 5 against recommending Arena’s highly anticipated new weight loss pill because the side effects were thought to outweigh the potential benefits: although human clinical trials found no evidence of increased cancer risk, animal studies showed that the drug was linked to a higher incidence of tumors, reported the Los Angeles Times.
According to the Associated Press, members of the FDA panel also raised concerns about higher rates of depression and memory loss among patients taking the new weight loss pill compared with those who took placebo.
The FDA new drug application was based on a package of data that included 18 clinical trials involving over 8,500 patients.
The pivotal trial, that evaluated over 7,000 obese and overweight patients, showed an average weight loss among those taking the active drug of 5.8 per cent compared with 2.5 per cent among those taking a placebo. According to agency reviewers, this difference sufficed to meet the FDA’s requirements by a “slim margin”.
However, the chairman of the FDA committee, Dr Abraham Thomas, who chairs the department of endocrinology at the Henry Ford Hospital in Detroit told the press that we need higher limits for effective weight loss drugs.
Thomas, who voted to approve the drug, said the panel was also concerned that Arena’s study excluded patients with diabetes and cardiovascular disease, two groups of patients likely to comprise a large proportion of those who would be receiving the drug should it gain approval.
Part of the argument in favour of approval is thought to be that against a background of US obesity rates nearing 35 per cent of the adult population, and so few treatment options on the market, even small amounts of weight gain could be meaningful.
Arena said in a statement that they will be working closely with the FDA as they complete their review of the new drug application. The company is said to be already studying the new drug in diabetes patients.
Panel member Dr Edward W Gregg, chief of the Epidemiology and Statistics Branch at the US Centers for Disease Control and Prevention (CDC), said the drug was “promising” but “not quite there yet”, reported WebMD.
Lorcaserin is thought to work by stimulating the serotonin 2C receptor in the brain: stimulating this receptor in the hypothalamus has been linked to changes in feeding behaviour and feelings of fullness (satiety), according to information from the drug company.
Earlier this week, the same FDA panel voted 8 to 8 on whether to keep Abbott’s weight loss drug Meridia on the US market. European regulators banned Meridia earlier this year.
The FDA panel was concerned that Meridia, which works in a similar way to lorcaserin by suppressing appetite, should only be available to people with no history or risk of cardiovascular disease, since recent studies showed it increased the risk of heart attack and stroke in this group.
In July, the FDA panel voted against approving the obesity drug Qnexa, made by Vivus, because of safety concerns.
Meridia and Xenical,also sold over-the-counter as Alli, are the only two FDA-approved prescription weight loss drugs currently available in the US.
The panel is expected to meet again in December to review another obesity drug made by Orexigen Therapeutics.
The FDA is not required to follow the advice of its advisory panels, but it usually does. The agency is due to decide on lorcaserin on 22 October.
Sources: Los Angeles Times, Associated Press, WebMD, FDA, Arena Pharmaceuticals.
Written by: Catharine Paddock, PhD