WASHINGTON — The Food and Drug Administration is one step away from approving a new kind of diet drug, provided its manufacturer can clear up concerns about the drug's possible link to breast cancer.
The drug, Xenical (pronounced ZEN-i-cal), could be the much-sought successor to the popular diet drug combination known as fen-phen, which all but ended when one of the two drugs in its potent formula was pulled from the market in September after being linked to potentially life-threatening heart valve problems.
An FDA advisory committee unanimously recommended Xenical last year, but later examination of clinical trials showed a slightly higher number of cases of breast cancer in women taking the drug than in those on a placebo.
The manufacturer, Hoffmann-LaRoche Inc. of Nutley, N.J., presented evidence that almost all the cases of breast cancer existed before the trial began. Still, a second advisory committee split, 5 to 5, on whether to recommend approval.
But company officials voiced optimism Thursday that they can satisfy FDA concerns and have the drug licensed early in 1999. "We are extremely pleased with the FDA's decision and are confident that we will be able to fulfill whatever requirements they decide they need by the beginning of 1999," said spokeswoman Valerie Suga.
Xenical is the first of a new class of anti-obesity drugs known as lipase inhibitors. They block the body's production of lipase, an enzyme necessary for the breakdown of fat molecules. The drug prevents about 30% of fat that is eaten from being absorbed in the gastrointestinal tract.
"The drug works nicely--people lose weight and they keep it off as long as they stay on the drug," said John Foreyt, director of the nutrition research clinic at Baylor College of Medicine in Houston. "But it is not a panacea. You still have to maintain a healthy lifestyle--eat right and exercise. But the drug does help with the dietary part."
He said the drug is "for people who are seriously obese," meaning "about 40 or more pounds overweight," and that using it can result in a 10% loss of body weight. He said participants in the studies lost an average of 20 pounds.
Company officials said they recently received a letter from the FDA saying the agency is ready to license the product but needs additional reassurance about a higher-than-expected number of breast cancer cases among women who took the drug during clinical trials.
Company officials said they have been talking to the agency about providing the necessary data in coming months.
Americans are constantly looking for a miracle pill for weight control, both for cosmetic and health reasons. About 58 million Americans suffer from obesity, which contributes to diabetes, high blood pressure and other potentially serious conditions.
Of 1,642 women older than 45 who participated in the studies of Xenical, 12 taking the drug developed breast cancer, whereas only three taking the placebo developed the disease. Company officials, however, pointed out that a larger number of women were taking the drug, compared with the placebo group--579 on the placebo and 1,069 on the drug--so the higher number of cancer cases was not surprising.
The company also presented evidence that almost all of the cases of breast cancer--11 of the 15--existed before the trial began.
Foreyt, who conducted a two-year study of Xenical, said he believes the drug is safe and called the breast cancer cases "a statistical fluke."
Almost three times as many patients taking the drug, administered orally in 120 milligram capsules three times a day, lost 10% or more of body weight compared with those taking the placebo, the company said. Nearly twice as many patients lost at least 5% of body weight, compared with those on the placebo.
The drug also significantly lowered cholesterol and blood pressure levels, the company said.