Would-be diet-drug manufacturer Arena Pharmaceuticals and Eisai, its Japanese partner, are out with fresh test results to bolster their case for approval of an experimental weight-loss pill.
The latest results: A little more than a third of diabetic patients who took a 10 milligram dose of lorcaserin twice a day for a year lost at least 5 percent of their body weight. For comparison, about 16 percent of those taking placebo lost the same amount of weight.
But the average weight loss with drug was less dramatic — about 4.5 percent, or around 10 pounds, for all the patients taking the 10 milligram dose twice daily. That's less than the 5 percent the FDA considers success for a weight-loss drug.
In September a panel of experts recommended against FDA approval of the drug. And last month, the agency agreed, sending Arena a letter that laid out a bunch of the problems. Safety issues are big, including tumors in rat experiments.
In the latest data there's something else to worry about.
Ultrasound exams found heart valve problems in 2.9 percent of the diabetics who'd taken 10 milligrams of lorcaserin twice daily for a year compared with only 0.5 percent of placebo patients.
The company said the groups of patients weren't big enough to reach a statistically meaningful conclusion about the valve issue.
Still, it was damage to heart valves that did in the once-popular diet-drug combination fen-phen. That debacle and the more recent move to take diet drug Meridia off the market hang over the lorcaserin and other diet drugs in development.
As Forbes' Matthew Herper tweeted on the news, "I've had time to think about the [Arena] data, and I'm getting more worried. This doesn't kill [lorcaserin], but odds are going down."