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Arena Pharma - Thinned Out

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Shares of Arena Pharmaceuticals Inc. (ARNA) slumped more than 42% to $2.17 in after-hours trading Thursday after an FDA panel rejected the company's weight-loss drug Lorcaserin.

Arena submitted its New Drug Application for Lorcaserin last December based on its pivotal phase III clinical trial program, BLOOM (Behavioral modification and Lorcaserin for Overweight and Obesity Management) and BLOSSOM (Behavioral modification and LOrcaserin Second Study for Obesity Management).

The FDA panel members who reviewed the New Drug Application for Lorcaserin on Thursday voted 9 to 5 that the available data do not adequately demonstrate that the potential benefits of Lorcaserin outweigh the potential risks, when used long-term in a population of overweight and obese individuals to allow marketing approval.

Earlier in the week, Arena's shares dropped as much as 42% after briefing documents released on Tuesday ahead of the panel meeting, concluded that Lorcaserin has only a slim efficacy and also raised concerns about its side effects including, heart problems, psychiatric issues like depression and cognitive events and worst of all - preclinical tumors.

The safety issues - most notably malignant tumors in rats, have come as a big surprise to industry analysts who were optmistic that the drug was safe and effective enough to pass the regulatory muster.

In July, Arena inked a marketing and supply agreement with Eisai Inc., the U.S. pharmaceutical operation of Tokyo-based Eisai Co., Ltd. for Lorcaserin, if approved. Arena, which has spent 12 years developing Lorcaserin and has no marketed drugs, has a lot riding on the diet-drug's approval.

Though the FDA generally follows the recommendations of its advisory panels, it is not mandatory to do so. The FDA is slated to decide on Lorcaserin on October 22.

Commenting on the panel outcome, Jack Lief, Arena's President and CEO of Arena Pharma said," We believe that Lorcaserin has a positive benefit-risk profile and represents a potential advance in the treatment of obesity. We will work with the FDA as the agency completes its review of the lorcaserin new drug application."

Lorcaserin is the second diet-drug to be shot down by the FDA panel in recent months. In mid-July, a federal advisory committee turned down Vivus Inc.'s (VVUS) experimental once-daily weight loss pill Qnexa due to safety concerns. A final decision by the FDA on Qnexa is expected by October 28.

Apart from Vivus and Arena, one more company is in the race to develop a diet drug - Orexigen Therapeutics Inc. (OREX ) with its investigational drug Contrave. The FDA panel is scheduled to review Contrave on December 7.

The market for anti-obesity drugs is virtually untapped and continues to hold a glittering allure. Till date there has been no 'silver bullet' remedy for obesity.

According to the National Center for Health Statistics, 34% of American adults are obese and 32.7% are overweight. A person with a body mass index, or *BMI, of 25-29.9 is said to be overweight, while an obese person will have a BMI of 30 or more. (*BMI is a measure of body fat based on height and weight).

The UN's World Health Organisation, or WHO, estimates that in 2015, the number of obese people around the world will surge to more than 700 million, up from 400 million adults who were obese in 2005.

The drug therapy for treatment of obesity has a checkered past. The long-term safety of the weight-loss drugs continue to pose a challenge for their development. A couple of approved diet drugs have been recalled, following reports of adverse side reactions like heart damage.

Fen-phen, a combination drug of Phentermine and Fenfluramine, and a related drug Redux marketed by Wyeth, now a part of Pfizer Inc. (PFE), were withdrawn from the U.S. market in September 1997 after the drugs were found to be associated with a serious heart condition known as valvular regurgitation, or leaky heart valves.

Yet another diet drug to be taken off the market was Sanofi-Aventis' (SNY) Acomplia. The drug was approved in the EU (European Union) in 2006. However, with new data from post-marketing trials linking the drug to serious psychiatric disorders, Sanofi-Aventis on the recommendation of the EMEA, withdrew Acomplia from the European markets in late October of 2008.

The approved weight-loss pills on the market have limited effectiveness and have unpleasant side effects. Abbott Laboratories' (ABT) Meridia and Roche's Xenical are FDA-approved prescription anti-obesity drugs. GlaxoSmithKline plc's (GSK) Alli is the only FDA-approved, over-the-counter weight-loss product.

The safety and efficacy of Meridia have been questioned by its opponents ever since reports of adverse reactions to the diet drug surfaced in 2002. That year, the consumer-protection group Pubic Citizens petitioned to the FDA to recall Meridia saying that the risk of use outweighed the benefit, and described the drug as "unacceptably dangerous."

However, in 2005, the regulatory agency refused to ban Meridia saying "overall risk-benefit profile supports it remaining available as a prescription drug for the treatment of appropriately selected obese patients.

In January of this year, the FDA toughened warning label on Meridia about the increased risk of heart attack and stroke in patients with a history of heart problems. A federal advisory panel, which met as recently as September 15 to decide whether or not to allow Meridia on the market, rendered a split decision - with eight members voting to pull the drug from the market and eight members voting to keep the drug on the market with new restrictions and more stringent warnings.

In May, warnings about the possible risk of liver injury were added to Alli and Xenical labels.

With the FDA raising the safety bar for drug approvals, it remains to be seen if any or all three diet drugs will be able to reach the pharmacy shelf.

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