Recently, the success of the second large late-stage study of its weight-loss drug, lorcaserin, was announced by Arena Pharmaceuticals Inc. However, Wall Street was disappointed when the strength of the results was compared to other drugs being developed. 
 
The San Diego drug developer is competing hard with Vivus Inc. (VVUS) and Orexigen Therapeutics Inc. (OREX) to come up with a novel obesity treatment, which possesses a multi-billion dollar market.

As per the viewpoint of Arena, the data from the study, dubbed Blossom, was in line with the Food and Drug Administration's guidance for effectiveness to acquire marketing approval.

While the data displayed a clean side-effect profile, Arena is gearing to apply for marketing approval in December and also commence partnering talks with a large pharmaceutical company, immediately. 

A conference was held Friday, where Arena executives described the drug as a game changer and expected that the drug will be a preferred first-line therapy for primary care physicians because of its lack of side effects.

However, the effectiveness of the drug lags that of the others in development.

“The results were at the bottom of the range for late stage candidates, only approximating regulatory requirements, of questionable clinical significance and unlikely to support partnership,” said Barclays Capital analyst Jim Birchenough.  
 
However, the drug’s prospects were defended by analyst Bret Holley of Oppenheimer, who said that lorcaserin's safety will lead it to be combined with other treatments and bring a "meaningful place in the obesity armamentarium."

“Under FDA guidelines for clinical trials of obesity treatments, one of two goals must be met. A trial must show that at least 35% of the drug group lost at least 5% of body weight, but that group must be approximately double the percentage of patients with similar weight loss on the placebo. Alternatively, a study can show that patients had an average weight loss that was at least five percentage points higher than the placebo group's loss,” said a source. 

Arena’s data was unsuccessful in meeting the second benchmark; and 47.2% of the patients on the drug lost at least 5% of their weight, compared to 25% taking the placebo. Arena believes the FDA will accept the success of the trial because the drug arm is "approximately" double the placebo group, though it isn't double. 

Jack Lief, Arena's chief executive said: “The one-year trial included more than 4,000 patients and found that those taking the drug twice a day lost 5.9% of their weight on average, compared to 2.8% on placebo, a difference of 3.1 percentage points.”