* Biotech says Contrave effective, risks can be managed
* FDA to ask panel if heart safety trial needed first
* Contrave sales could reach ${esc.dollar}1.2 billion by 2018
* Outside FDA advisers make recommendation later Tuesday (Rewrites with comments from meeting)
By Susan Heavey
WASHINGTON, Dec 7 (Reuters) - Orexigen Therapeutics Inc <OREX.O>, maker of the last of a trio of new weight-loss drugs to come before U.S. regulators this year, says its pill can safely help patients shed pounds and contends further study of heart risks should be done after approval.
The biotech company, appearing before a panel of medical advisers on Tuesday, is hoping to avoid the fate of two rival drugs that were rejected by the Food and Drug Administration in October.
Orexigen officials faced questions from the FDA panel of outside advisers about its pill Contrave's effect on blood pressure and pulse rates, among other safety concerns.
The FDA will ask the advisers whether Orexigen needs to run a longer study of heart risks before or after getting marketing approval. The FDA's final decision is expected by Jan. 31.
Shares of Orexigen have fallen 36 percent this year as investors worry whether the biotech can succeed where rivals have failed, aiming to tap into a potentially major market in the United States, where rates of obesity continue to soar.
Its shares were halted on Tuesday ahead of the panel's recommendations later Tuesday. Final votes are expected by 5 p.m. EST (2200 GMT).
Drugmakers seeking a pill to help people slim down have been thwarted for decades by serious side effects, and few options remain on the U.S. market even though two out of three Americans are overweight or obese. [ID:nN29219928]
In October, the FDA rejected Arena Pharmaceuticals Inc's <ARNA.O> pill, citing cancers seen in animal studies, and Vivus Inc <VVUS.O> was asked for more data on heart risks.
Eric Colman, deputy director of the FDA division that oversees weight loss and related drugs, said panelists should pay close attention to Contrave's effect on the heart. "This is probably the more important issue we'll be discussing today."
Dawn Viveash, head of regulatory affairs for Orexigen, said the company was "aware of the challenges" of trying to bring a new diet drug to market but that it had learned from its rivals' fates and was prepared to make its best case.
"The road has been long and hard both for individual drugs as well as for the class," Viveash told the panel. Contrave's "safety profile is well characterized ... the known risks can be managed."
Approval is key to California-based Orexigen, which focuses solely on obesity drugs and has no products on the market yet.
According to data from BioMedTracker, Contrave sales could reach ${esc.dollar}1.2 billion by 2018. That figure would make it the top player in a U.S. weight-loss drug market that sees just ${esc.dollar}382 million annually, according to IMS Health.
ANOTHER TRIAL, NOW OR LATER?
Contrave combines the alcohol and drug addiction drug naltrexone with the antidepressant bupropion in an attempt to boost metabolism while curbing appetite and cravings.
Orexigen, which has partnered with Takeda Pharmaceutical Co Ltd <4502.T>, said the 25-year history of both ingredients was an advantage because many safety issues are already known.
The pill meets FDA effectiveness guidelines, in that at least 35 percent of patients studied lost at least 5 percent of their weight.
Orexigen told panelists any modest risks were overcome by the notable effect of weight loss in reducing the risk for chronic diseases linked to obesity such as diabetes.
It said studies showed a slight increase blood pressure and pulse rates for Contrave patients versus those given a placebo but that overall rates were similar.
But FDA's primary reviewer of the drug, Eileen Craig, said, "It is not known how these vital sign changes would impact cardiovascular risk in the long term."
FDA and Orexigen are already in talks about another trial to look more closely at whether those heart issues signal potential for greater cardiovascular side effects.
Such a trial can only reasonably be done after approval, company representatives argued, saying it would have to study tens of thousands of patients over several years.
Several panelists, in early discussion, questioned the adequacy of the company's 12 months of data, given that Orexigen is seeking approval for long-term use. (Reporting by Susan Heavey; Editing by Tim Dobbyn, Dave Zimmerman)
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