By Michael Fitzhugh
A new weight loss drug developed by Arena Pharmaceuticals (NASDAQ:ARNA) caused cancer in lab rats and succeeded by just “a slim margin” in meeting the U.S. Food and Drug Administration’s expectations for weight management, a review by the agency concluded.
News of the findings spurred a sell-off that drove Arena's shares down 38 percent to $4.27 as investors fretted over a vote on the drug, lorcaserin, by the FDA's Endocrinologic & Metabolic Drugs Advisory Committee. The committee, which meets September 16, will vote on whether to recommend approval for the drug to FDA officials.
Arena developed lorcaserin to help obese and overweight patients, with at least one weight-related co-morbid condition, shed pounds and maintain weight loss. Although the drug is similar to fenfluramine, a component in the ill-fated diet pill fen-phen, studies showed it was not linked to heart valve damage.
While different, lorcaserin has been associated with other problems, according to the FDA briefing document. A safety assessment of the drug focused on concern about the development of multiple tumor types in a carcinogenicity study in rats and impairments in attention and memory in some clinical trial participants testing the drug.
In two late-stage trials of the drug, people taking lorcaserin lost an average of three percent more weight than those taking a placebo. That fell short of the five percent recommended weight loss the agency has suggested. A 10 milligram dose of the drug did, however, “by a slim margin, satisfy the categorical efficacy criterion,” wrote Eric Colman, deputy director of the FDA’s Division of Metabolism and Endocrinology Products.
Arena has not commented on the findings yet, but has scheduled a conference call to discuss its outcome at 7 a.m. Eastern Time on September 17, ahead of the October 22 PDUFA date set for lorcaserin.
Tokyo-based Eisai (OTCPK:ESALY), which has an exclusive deal for the U.S. rights to commercialize lorcaserin, has not commented on the findings either. Its shares also fell briefly Tuesday.
Qnexa, another experimental obesity drug, met with disappointment when the Endocrinologic and Metabolic Drugs Advisory Committee met in July to discuss safety concerns that led them to recommend against approval. The FDA is due to decide its fate by October 28.
Other recipients of bad news in the obesity realm this year have included Abbott's (NYSE:ABT) Meridia, which on Monday was linked to increased risks of heart attack and stroke risk, Roche's (OTCQX:RHHBY) Alli and GSK’s Xenical. In May, the latter two orlistat-based medicines, got new labels warning patients about the risks of liver failure or liver death.
About two thirds of American adults are overweight, leaving many vulnerable to serious medical consequences, such as type 2 diabetes, cardiovascular disease, cancer and depression.