UPDATED: Orexigen nabs long-awaited FDA approval for obesity drug Contrave

Orexigen CEO Michael Narachi

More than three long years after Orexigen Therapeutics ($OREX) was turned back at the FDA and forced to do a costly late-stage safety study of its weight drug Contrave, the agency has come back and given its seal of marketing approval to the drug. The obesity treatment will now weigh in against two struggling therapies that got a head start on cracking the tough market. But it may be only a step ahead of a hungry Novo Nordisk ($NVO), which is in the final stages of seeking an approval for its own heavyweight contender for the crown of bestselling obesity drug. And a tough label warning patients about potential neuropsychiatric and cardiovascular risks may well hamper the drug's sales potential.

"Obesity continues to be a major public health concern," said Dr. Jean-Marc Guettier, director of the Division of Metabolism and Endocrinology Products in FDA's Center for Drug Evaluation and Research. "When used as directed in combination with a healthy lifestyle that includes a reduced-calorie diet and exercise, Contrave provides another treatment option for chronic weight management for people who are obese or are overweight and have at least one weight-related health condition."

Investors were seeing red, though, sending shares of the biotech down more than 5% minutes after trading resumed mid-morning Thursday.

Orexigen CEO Michael Narachi has been supremely confident that once he got his hands on an approval, major sales success could be only one step behind. His trump card: A big group of sales reps at Takeda, which is partnered on the therapy and plans to roll it out in style. In a call with analysts on Thursday, Orexigen execs said that about 900 Takeda sales reps will be involved in the marketing debut.

Arena (Belviq) and Vivus (Qsymia) won approvals for the first new weight-loss pills in more than a decade back in 2012, but each has struggled to rack up significant sales.

La Jolla, CA-based Orexigen all but threw in the towel back in 2011, when the agency insisted on a new late-stage study to nail down clear evidence of its safety. But the biotech eventually decided to come up with the $100 million needed for the additional cardiovascular trial. An interim analysis last fall on the 10,000 patients recruited for the study confirmed what the biotech was looking for, setting the stage for a resubmission.

The drug is approved for use in adults with a body mass index of 30 or greater or adults with a BMI of 27 or greater who have at least one weight-related condition such as high blood pressure (hypertension), Type 2 diabetes, or high cholesterol (dyslipidemia), the FDA noted.

A history of safety issues involving weight drugs tied to trial data reflecting only marginal weight loss among patients has made it hard for the early entries to gain substantial coverage from payers in the U.S. And the FDA's approval comes with significant strings. Orexigen is being required to carry out a follow-up outcomes trial on cardiovascular risks, two pediatric studies and more trials on cardiac conditions, renal and hepatic impairment and drug-drug interactions. 

The label is also likely to crimp sales of Contrave, a combination of naltrexon and bupropion. "The effect of Contrave on cardiovascular morbidity and mortality has not been established," patients are warned. The drug is tied to higher blood pressure rates and, because it includes bupropion, includes a harsh warning on potential neuropsychiatric side effects. The FDA notes that the label includes "a boxed warning to alert healthcare professionals and patients to the increased risk of suicidal thoughts and behaviors associated with antidepressant drugs."

On Thursday Novo Nordisk will face a panel of outside agency experts who will review its application of liraglutide 3 mg, a higher dose of a GLP-1 drug that is approved as Victoza for diabetes and represents a major effort on the Danish pharma company to tackle one of the chief causes of diabetes.

- here's the release