THE controversy surrounding drugs intended to help people lose weight has
deepened. Last week, a panel advising the US Food and Drug Administration (FDA)
split down the middle over whether to approve a new diet aid called orlistat,
because of concerns that it might cause breast cancer in some women.
The developed world is facing an epidemic of obesity, so drugs to treat the
problem are much in demand. Orlistat, made by the Swiss-based multinational
Hoffmann-La Roche, blocks the absorption of fat from the gut, allowing up to 30
per cent to pass through the body.
Last May, the FDA’s Endocrinologic and Metabolic Drugs Advisory Committee
recommended approving orlistat for sale. But the FDA became concerned about a
clinical study in which 10 of 1016 women who took the drug developed breast
cancer. Only one of the 579 women given a placebo developed the disease.
Roche resubmitted its application in November. The company says the cancers
were diagnosed so soon after the trial started that it is unlikely the drug was
to blame. Animal studies also show no evidence that it causes cancer.
But last week, the advisory committee split five votes to five on whether to
recommend orlistat for approval. The FDA will now have to decide whether to go
ahead without clear guidance from its advisers.
“I don’t think anybody was convinced there was a clear effect on breast
cancer,” says Mark Molitch of Northwestern University Medical School in Chicago,
a member of the committee. “Some people were concerned that the possibility had
not been excluded.”
Molitch believes the panel decided to “err on the conservative side”
following a scare about another diet drug. Last September, the FDA asked
Wyeth-Ayerst Laboratories of Philadelphia to withdraw its drug fenfluramine,
which reduces appetite. It was suspected of causing a rare heart valve disease
in some patients
(This Week, 20 September 1997, p 7).