FDA cites low weight loss and safety questions with Arena Pharmaceutical’s experimental drug

FDA questions safety, effectiveness with diet pill

WASHINGTON — Federal health officials dealt a surprising blow on Tuesday to an experimental diet pill that was thought to offer a safer way to shed pounds after decades of dangerous side effects reported with weight loss drugs. The Food and Drug Administration said the pill, developed by Arena Pharmaceutical, produced minimal weight loss while raising concerns about heart damage, depression and other problems.

Shares of Arena Pharmaceuticals Inc. fell $2.72, or 40 percent, to $4.13.

The company’s lorcaserin is one of three drugs racing to be the first new prescription weight loss pill approved by the Food and Drug Administration in more than a decade. While lorcaserin’s weight loss results trail competitors, analysts have predicted it would win FDA approval thanks to a stellar safety profile.

However, in a review posted online, FDA scientists said the drug barely met the agency’s threshold for weight loss effectiveness and raised safety concerns about side effects, including heart valve disease and psychiatric problems.

Arena studied the drug in more than 7,000 obese and overweight patients. After one year, the average weight loss among lorcaserin patients was 5.8 pounds, compared with 2.5 pounds among patients taking a dummy pill. That difference was enough to meet FDA’s effectiveness requirements “by a slim margin,” according to reviewers. Elsewhere, scientists described weight loss with the drug as “relatively low.”

On Thursday the FDA will ask a panel of experts to assess lorcaserin’s effectiveness and safety. Specifically, panelists will be asked if the company should conduct more studies to rule out the possibility that its drug leads to heart valve disease. The agency is not required to follow the panel’s advice, although it often does.

The quest for a blockbuster weight loss drug has eluded nearly every major pharmaceutical firm over the last four decades. A slew of prescription weight loss offering have been associated with cardiovascular problems, most notably Wyeth’s diet pill combination fen-phen. The drug was pulled from the market in 1997 because of links to heart valve disease.

Lorcaserin targets the same appetite pathway as fen-phen but in a more selective, and what was thought to be safer, manner.

The FDA is reviewing two other new weight loss drugs, both which showed greater weight loss than lorcaserin.

California competitor Vivus Inc.’s Qnexa has shown the largest weight reductions, with patients losing between 13 and 15 percent of their body mass. But the drug was panned by an FDA panel in July because of safety concerns, ranging from heart palpitations to suicidal thoughts. Orexigen Therapeutics Inc. of La Jolla, Calif., has shown weight loss between 5 and 10 percent with its diet drug Contrave, which the FDA will review at a public meeting in December.

Analysts pegged lorcaserin as the safest bet of the group because of its safety profile. But the FDA’s review suggests the agency wants to see more data before making a ruling on the drug’s safety. And even then, it’s unclear regulators would be willing to accept small safety concerns from a drug that showed such meager efficacy results.

Jefferies & Co. analyst Thomas Wei downgraded Arena shares to “Underperform,” on Tuesday, saying the FDA’s review highlights so many safety issues it “introduces a question of whether new data could even satisfy the threshold for approval.”

On Wednesday, the same panel of FDA advisers will discuss heart problems with an older drug, Meridia, which has been on the market since 1997. European regulators pulled the Abbott Laboratories drug off the market in January, based on a study that showed higher rates of heart attack and stroke. The FDA is still considering what action to take on the drug, although agency reviewers suggested the drug’s modest benefits don’t outweigh its heart risks.