Arena's Obesity Drug Shows Promise, Stock Moves Wildly


A Food and Drug Administration advisory panel today voted against approval of Vivus (VVUS) weight loss drug Qnexa. But while trading in Vivus shares was halted pending the crucial vote, rival Arena Pharmaceuticals (ARNA) shares soared as much as 35% after releasing study results showing its obesity drug lorcaserin helped patients lose weight and keep it off. Alas, following the negative vote on Qnexa, Arena shares tumbled and it closed down 8.41%.

The data from a two-year trial called BLOOM, which were also published in the the New England Journal of Medicine, show that 47.5% of patients taking lorcaserin and also involved in behavioral modification lost 5% of body weight. Only 20.3% in the placebo group achieved the same goal. Nearly three times as many patients achieved at least 10% weight loss in the lorcaserin group than in the placebo group. The lorcaserin group shed 8.2% of their weight, or 18 pounds, the placebo group lost seven pounds.

Not only that, but in the second year, those who continued to take lorcaserin were significantly better able to maintain their first year weight loss than those who were switched to placebo.

In addition, lorcaserin also improved blood pressure, heart rate, cholesterol, insulin resistance, levels of inflammatory markers and blood pressure -- all of which are markers for future cardiovascular events.

Among the most frequent adverse events reported with lorcaserin were headache (18.0% vs. 11.0%, lorcaserin vs. placebo); dizziness (8.2% vs. 3.8%); and nausea (7.5% vs. 5.4%).

Lorcaserin binds to a receptor in the brain in an area involved in the control of appetite and metabolism, while avoiding a target in the heart that was linked to valve damage, according to Arena. Eisai recently bought marketing rights to Arena's drug.

Arena claims its drug has a better safety profile, which could be important come its time to stand in front of the FDA panel. The FDA is set to review lorcaserin on September 16.

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