Orexigen Tanks After-Hours on Obesity Data

Obesity patients treated with a weight-loss pill from Orexigen Therapeutics (OREX Quote) lost an average of 20.3 pounds, or 9.3% of their body weight, over one year, according to results from a phase III study released Thursday.

Orexigen said the study of its weight-loss drug Contrave met all its pre-specified efficacy and safety goals. However, patients in the trial who took a sugar pill for one year lost an average of 11 pounds, or 5.1% of their body weight.

That puts the placebo-adjusted percentage of body weight lost by Contrave patients at 4.2% -- below the 5% weight-loss standard for approval mandated by the U.S. Food and Drug Administration for all experimental obesity drugs.

Orexigen Chief Financial Officer Graham Cooper says the company is pleased with the results of the study because Contrave patients lost significantly more weight than placebo patients. The study was made more challenging because all patients, whether treated with Contrave or placebo, received extensive counseling and were enrolled in strict exercise and diet programs.

"It's no surprise to us that placebo patients lost as much weight as they did given the extensive behavioral modifications in the study," said Cooper, in an interview. "We expected to see a smaller placebo-adjusted weight loss."

In a previous phase II study of Contrave, patients lost between 6% and 7% of their body weight, adjusted for placebo, lower than the 4.2% reported in the phase III study Thursday.

In the phase III study, 41.5% of the Contrave patients lost 10% or more of their body weight over one year compared to just over 20% of placebo patients. This doubling of the percentage of patients who lost significant weight is another way to win over FDA reviewers, added Cooper.