US government health officials today said that an experimental diet drug produced minimal weight loss, while raising safety questions about its effects on the heart.
Arena Pharmaceuticals’ lorcaserin is one of three drugs racing to be the first new prescription weight loss pill approved by the US Food and Drug Administration (FDA) 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”.
The FDA will tomorrow ask a panel of experts to assess lorcaserin’s effectiveness and safety. Specifically, panellists 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 number of prescription weight loss offerings 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 of which showed greater weight loss than lorcaserin.
California competitor Vivus’s Qnexa has shown the largest weight reductions, with patients losing between 13 and 15% 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, of La Jolla, California, has shown weight loss between 5 and 10% 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.
Even then, it’s unclear regulators would be willing to accept even small safety concerns from a drug that showed meagre efficacy results.
Shares of Arena Pharmaceuticals fell $2.63, or 38.4%, to $4.22 in early trading today following news of the report.