An experimental obesity pill from Arena Pharmaceuticals Inc won the support of U.S. advisers on Thursday, as public health advocates push for new solutions to the nation’s growing obesity epidemic.

A panel of outside experts to the Food and Drug Administration voted 18 to 4 to recommend approval of lorcaserin, bringing the drug a step closer to U.S. approval as one of the first new weight-loss treatments in over a decade.

Lorcaserin is Arena’s most important product.

Shares of Arena, which were halted pending the panel vote, nearly doubled in value to $6.92 after closing at $3.66 on Wednesday.

Arena’s pill is one of three new potential obesity treatments vying to gain U.S. approval and be the first new weight-loss treatment on the market after initial rejections over safety issues.

The FDA first rejected lorcaserin, which is being developed in partnership with Japanese drugmaker Eisai Co Ltd, in October 2010, citing potential cancer risks.

Arena resubmitted its application with more data after the 2010 rejection to show that the previous findings of tumors in rats did not apply to people, which seemed to soothe some of the FDA’s concerns.

The advisory committee members still had some concerns about side effects, especially uncertainty about heart valve problems, but most said these concerns could be addressed in post-approval studies.

The panelists were also concerned about the drug’s modest weight loss, but said overweight and obese patients needed more options.

“Currently the options available to obese patients are very limited, and severely obese patients are willing to accept a high degree of risk,” said panel member Dr. Daniel Bessesen, chief of endocrinology at the Denver Health Medical Center.

“And while it isn’t an ideal drug… I think it will be a useful adjunct,” said Bessesen.

The FDA often follows panel recommendations, although it is not required to. It is due to make a final decision by June 27.

After the panel vote, Arena and Eisai said they were expanding their partnership.

If the drug is approved, Arena will manufacture lorcaserin at its facility in Switzerland, then pass it to Eisai for distribution in most of North and South America, including Canada, Mexico and Brazil.

Obesity, a leading cause of diabetes, heart disease and other serious health problems, has reached epidemic proportions in the United States with nearly a third of the population falling into the category.

The pricetag of obesity has also soared, with the condition contributing an additional $190 billion a year in healthcare costs, or one-fifth of all healthcare spending.

But the FDA has set a very high approval bar for weight loss drugs because such a large portion of the general population is likely to want to take them.

FOCUS ON SAFETY

Vivus Inc and Orexigen Therapeutics Inc have also tried to get obesity pills approved in the last two years but been rejected because of safety.

Vivus resubmitted its pill Qnexa, and won the backing in February of the same advisory panel that voted in favor of lorcaserin. The FDA has pushed back its final decision on Qnexa by three months to July 17 in order to review the company’s risk evaluation plan for the drug.

Vivus shares closed down 0.3 percent on Nasdaq on Thursday, while shares of Orexigen, which is still testing the heart safety of its obesity drug Contrave, closed down 6.4 percent.

In a review earlier this week, staff from the FDA said Arena’s pill appeared to help people lose weight and was unlikely to cause tumors in humans, but questioned if the company had provided enough data to rule out heart valve problems.

Heart problems have dogged the obesity field for decades, making the FDA especially cautious about any potential issues.

Arena’s lorcaserin was designed to block appetite signals in the brain in a similar way to “fen-phen,” an infamous diet pill that was pulled from the market in 1997 after reports of sometimes fatal heart-valve problems.

Another diet pill, Meridia, was withdrawn in 2010 after also being linked to heart problems.

Some FDA advisers questioned whether the smaller weight loss of Arena’s pill, compared to the drugs from Vivus and Orexigen, justified its uncertain heart risks.

Lorcaserin helped people lose at least 5 percent of their weight compared to placebo, meeting the FDA’s threshold, according to a combined analysis of three clinical trials for the drug. But if any of the trials were analyzed alone, the drug did not meet the bar, FDA staff said earlier.

“There remains a lingering uncertainty regarding potential (heart valve disorder) associated with lorcaserin, especially given the weight loss that’s observed,” said Dr. Sanjay Kaul, an influential cardiologist from Cedars Sinai Medical Center in Los Angeles, who voted against lorcaserin.

Most panel members suggested the company should study the risk of heart valve disorder after lorcaserin is approved, and make people who take it get regular echocardiograms.

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By Anna Yukhananov