Study Casts Doubt on Value of Obesity Drug

A study published today in the New England Journal of Medicine casts doubt on the value of an antiobesity drug that Amgen Inc. is developing.

The Thomas Jefferson University study found that as many of 95% of obese people already have plenty of leptin--the protein Amgen researchers believe is an important regulator of body fat and that might hold the key to solving obesity problems.

This study shows that “the discovery of [Amgen’s] fat gene is less important than we originally thought,” said analyst Jim McCamant, editor of the Medical Technology Stock Letter in Berkeley. “It does not look like that gene itself is critical in therapy.”

Amgen spokesman David Kaye dismissed the study findings, saying the Thousand Oaks company’s own tests have shown higher leptin levels in obese people and that that makes sense because leptin is produced from fat cells. “It does not mean, or has anyone proven, that resistance to leptin exists in humans. That obviously has to be evaluated in [human] clinical trials,” he said.

Kaye said Amgen will test the leptin drug on humans this year, as planned.

Amgen’s developmental drug, dubbed “the fat gene,” was licensed about a year ago with much hoopla from researchers at Rockefeller University. Amgen made an initial payment of $20 million to the university for rights to the drug.

The drug, cloned from mice by Rockefeller researchers, is thought to cause fat cells to produce a protein called leptin--the name comes from the Greek word meaning “thin.” In laboratory tests, mice that were given leptin lost as much as 40% of their weight. Amgen researchers believe that as you eat, more leptin is sent into the blood, so that giving leptin in drug form would trick the brain into thinking your stomach was full.

The search for a drug to fight obesity is now a hot field, as drug giants Hoffmann-La Roche, Eli Lilly, Glaxo Wellcome and Pfizer are all looking for drugs to supply what could be a multibillion-dollar market.

Roche’s recent research focuses on a receptor in the brain that processes information about fat levels, rather than leptin itself.

The latest study, led by Robert Considine, assistant professor of medicine at Jefferson University in Philadelphia, involved 275 patients. Considine’s team found that 90% to 95% of obese people had leptin levels as high as four times normal.

He concludes that “the majority of obese people have enough leptin, and so we feel they’re probably resistant” to any treatment that would focus on a leptin drug. Eli Lilly’s research team did some work with Considine on the study.

All of this obesity research provides “pieces of information that gives more knowledge about the disease and will lead over the years to some good treatments,” analyst McCamant said. As for Amgen, he said, “this doesn’t mean their work in this area will not lead to a good product.” But he said he now doubts that leptin will be the magic potion.

Amgen is the country’s most successful biotechnology company, thanks to two blockbuster drugs already on the market. But it has struggled for years to come up with a third. Last year, its research and development spending hit a record $452 million.

Amgen released its fourth-quarter results Wednesday. Excluding a one-time charge last year for an acquisition, fourth-quarter profit rose 18% to $145.6 million and revenue climbed 16% to $513.5 million, up from $442.9 million.

Amgen shares fell $1.19 to $60.125 on Nasdaq.