Orexigen Therapeutics Inc said study data showed its experimental obesity drug did not increase heart-related risks, sending its shares up 28 percent in premarket trading.
The drug, Contrave, was previously denied approval by the U.S. Food and Drug Administration, which cited potential heart risks. The FDA had requested an additional trial.
The company said on Monday it would resubmit its application for U.S. marketing approval for Contrave in the next few weeks, with a decision expected by June.
An interim analysis of the heart-risk study, named Light, showed that overweight and obese patients receiving Contrave did not have a higher heart risk, compared with those on a placebo.
"The interim analysis of the Light study clearly achieved the goal set by the FDA," Chief Executive Michael Narachi said in a statement.
Obesity has assumed epidemic proportions in the United States, creating a huge market opportunity for drugmakers.
Vivus Inc and Arena Pharmaceuticals Inc already have their obesity pills approved by the FDA. Vivus's Qsymia and Arena's Belviq were approved in mid-2012.
However, sales of both drugs till now have been disappointing due to safety concerns, and problems related to reimbursement and earlier obesity treatments.
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