HORMONE MAY AID WEIGHT LOSS; AMGEN CREATION USED FOR TRIALS AT UNIVERSITY.

Byline: Ben Sullivan Daily News Staff Writer

In what could be promising news for thousands of obese Americans, medical researchers said Sunday that a form of the naturally occurring hormone leptin appears to help some people lose weight.

At the American Diabetes Association's annual meeting under way in Chicago, researchers presented results of a study in which severely overweight individuals given high daily doses of leptin lost an average of 16 pounds over six months. The research, conducted at Boston's Tufts University, used a synthetic form of the hormone manufactured by Thousand Oaks-based Amgen Inc., which funded the study.

Leptin, first identified in 1994, is a naturally occurring hormone made in fat cells. In laboratory tests, mice genetically deficient in the hormone have been found to grow obese. But they get thinner when treated with leptin.

In the study announced Sunday afternoon, 60 obese patients were given daily injections of the hormone at varying concentrations. Both they and a control group given a placebo were also put on a diet that cut 500 calories from their normal food intake, and were given nutritional counseling.

Those injected with leptin lost an average of between 1.5 pounds at low doses, to 16 pounds for those at the highest dose. Patients who received the placebo lost an average of 3.7 pounds over six months. The only adverse side effect noted was skin irritation at the site of the injection.

But some outside observers were skeptical of the results Sunday.

In the first trials on humans, some people lost as much as 35 pounds after six months of daily injections, with no serious side effects, while others lost no weight and some even got pudgier.

``It's a disappointment,'' said an outside expert, Dr. Roger Unger of the University of Texas Southwestern Medical Center in Dallas.

Unger said it was possible that a place could be found for leptin treatment, ``but it doesn't appear from the abstract (of the study) that it's going to work for every possible obese person.''

Dr. Andrew Greenberg, who led the study and is director of research at the New England Medical Center's Obesity Consultation Center, said the results showed ``an acceptable safety profile, suggesting further study is warranted.''

Amgen spokesman David Kaye was more enthusiastic. ``This study proved three things: leptin is safe, it has a dose-dependent effect and it causes weight loss,'' Kaye said.

But Kaye cautioned that any marketable product derived from leptin research is still years away. The study completes the first phase of a three-step process of clinical testing that new drugs must undergo before being submitted to the Food and Drug Administration for approval. Phase II trials on leptin are now under way.

In a recent national survey, more than one-third of Americans were found to be obese, and the nation spends about $40 billion annually to stay or get slim. As witnessed with American Home Products Inc.'s Redux, which comprised half of the recently recalled fen-phen prescription diet pill combination, the potential market for weight-loss drugs is enormous. If leptin were to grab even a fraction of the market it would be a coup for Amgen.

The Ventura County firm is the world's largest independent biotechnology company. Since it was founded in 1980, Amgen's fortunes have been tied to the success of two bioengineered drugs - Epogen and Neupogen - which stimulate red and white blood cell growth, respectively. Last year, the drugs generated more than $2 billion in sales.

But Amgen has seen its sales growth slow in recent years and has no blockbuster products ready to make up the difference. Unfortunately, leptin is unlikely to change that, said Robert LeBoyer, a health care analyst at Genesis Merchant Group Securities in San Francisco.

Because the hormone must be injected daily, many people will shy away from its use, LeBoyer said. And 16 pounds lost in six months is not a dramatic result, he said.

``Fear of the needle could make people lose that much weight . . . and Jenny Craig could probably do something similar,'' he said.

Where LeBoyer sees the greatest potential market for leptin is in diabetics, for whom excess weight is often a contributing factor for the disease.

``This is not something I'd think of as a mega-Slim Fast,'' he said. ``This is something that would have to be medically justified at this point.''

--- The Associated Press contributed to this report.