Amylin obesity treatment trial fails to impress

NEW YORK (Reuters) - Amylin Pharmaceuticals Inc said on Thursday a mid-stage study of its combination obesity treatment yielded positive results, but investors were unimpressed and the company's stock rose just 1 percent.

The Phase II, 28-week study randomized 608 overweight or obese patients to either placebo or various doses of pramlintide, the active ingredient in Symlin, a drug used to treat diabetes, and metreleptin, a synthetic analog of the human hormone leptin, which is secreted by fat cells and plays a role in regulating metabolism.

Patients with a body mass index of less than 35 -- in other words, the less severely overweight subjects -- who were treated with the highest dose of the product, experienced 11 percent weight loss on average compared with 1.8 percent for those on placebo. The results did not excite investors.

"We continue to view this particular obesity opportunity with a degree of skepticism," Thomas Russo, an analyst at Robert W. Baird, said in a research note.

While the study showed no cardiovascular or neuropsychiatric side effects -- issues that have doomed other potential obesity treatments -- the drug must be injected several times a day, a potentially serious drawback to its popularity.

"The efficacy results look better than what we have seen with oral agents so far and we think the safety signals appear manageable," said Steve Yoo, an analyst at Leerink Swann. "It remains to be seen whether better efficacy will trump the inconvenience of twice daily injections in the marketplace."

Amylin said the results confirm previous mid-stage results with the combination product and "provide a solid foundation for the company's ongoing obesity development program."

Amylin shares rose roughly 1.1 percent to $12.43 in early afternoon trading on the Nasdaq.

(Reporting by Toni Clarke and Lewis Krauskopf, editing by Gerald E. McCormick and Matthew Lewis)