Orexigen puts obesity drug development on hold

NEW YORK — Orexigen Therapeutics Inc. said Friday that U.S. regulators are making "unprecedented" demands about safety trials for its obesity drug candidate Contrave, and it is putting on hold further work on securing approval in that market.

The San Diego company said it will focus on developing Contrave and another drug candidate, Empatic, in non-U.S. markets until there is a clear pathway to approval in the U.S.

Its shares tumbled $1.08, or 34 percent, to $2.10 in pre-market trading.

Orexigen said the U.S. Food and Drug Administration wants it to conduct a study on Contrave's heart side effects that is unprecedented and would generate much more information than is necessary or feasible.

The FDA said in February that Orexigen would need to conduct a new study of Contrave's heart side effects in order to get Contrave approved. Orexigen proposed a more limited study, saying it wanted to run a trial designed to demonstrate that major cardiovascular problems linked to Contrave did not present an unreasonable risk. The company also expressed interest in trying to get the drug approved for patients with a lower risk of heart problems.

However, the FDA's Division of Metabolic and Endocrinologic Products refused to approve Contrave even for low-risk patients without data from a cardiovascular trial.

Orexigen said the FDA plans to hold an advisory committee on cardiovascular risk assessment for obesity drugs in early 2012. According to Orexigen, the FDA said it might change any agreements about cardiovascular studies based on that advisory committee meeting.

Orexigen said it plans to appeal the FDA's responses through a formal dispute resolution process. The company will also will speed up exploration of non-U.S. markets. Orexigen said it plans to evaluate new opportunities, but did not specify what those opportunities are.

Contrave was considered the most promising of a group of three obesity drug candidates that were in development in the last few years. However the FDA said it was not willing to approve any of the products because of concerns about their side effects.

The agency was concerned about the effectiveness of Arena Pharmaceuticals Inc.'s drug lorcaserin, as well as a link to tumors when lorcaserin was studied on rats. The FDA hasn't approved Vivus Inc.'s drug Qnexa because one of its ingredients is linked to birth defects.