WASHINGTON (AP) - People with advanced lung cancer who have exhausted standard treatment gained a last-chance therapy Monday, a once-a-day pill called Iressa that shrinks tumors in a fraction of those terminally ill patients.
It's a controversial drug: Iressa already is sold in Japan, where the health ministry has linked it to 173 deaths from another pulmonary disorder, interstitial lung disease or ILD. So far, very few users of experimental Iressa in this country appear to get ILD, but it is fatal about a third of the time.
But the U.S. Food and Drug Administration said it had enough evidence that Iressa offered some hope for patients already dying of their cancer to approve its sale here even as that side effect and questions about Iressa's overall effectiveness continue to be studied.
Iressa treats non-small cell lung cancer, the most common form, but is only to be used as third-line therapy, after the two standard treatments fail, the FDA stressed.
One study of 216 advanced patients found 10 percent had their tumors shrink for at least a month while taking Iressa. Nobody yet knows if that translates into longer survival - manufacturer AstraZeneca continues to study that question. But the shrinkage seems to last at least seven months, said FDA oncology chief Dr. Richard Pazdur.
Particularly intriguing, the FDA said, is that Iressa seems to work significantly better for women - about 17 percent of women see tumor shrinkage vs. 5 percent of men. Also, it seems to work better for people who never smoked, FDA said, a conundrum because smoking is the main, though not sole, cause of lung cancer.
Yet there's a big mystery: Iressa had no effect when more than 2,000 patients with early-stage cancer took it together with regular chemotherapy in two more stringent studies.
Why? No one knows, although some scientists think combining regular chemotherapy with Iressa - which works by jamming one of a tumor's internal growth signals - could blunt the new drug's action.
Hence, the FDA put a warning label on Iressa stressing it is not for use with other chemotherapies during early lung cancer - and is requiring AstraZeneca to conduct more research to settle the issue.
Then there's the question of that rare but often fatal side effect.
Of about 28,000 Iressa users in Japan, about 2 percent have come down with ILD. But here, less than half a percent of some 23,000 people given Iressa in a special experimental program got ILD. And in the studies that compared Iressa to a dummy pill in people getting chemotherapy for early lung cancer, both groups came down with ILD equally - about 1 percent, the FDA said.
It can be hard to diagnose ILD in lung cancer patients, and other cancer treatments can cause ILD, too, said FDA drug chief Dr. Robert Temple. Even if it turns out that 1 percent of Iressa users gets ILD, that's not a big enough risk to outweigh the drug's potential benefit to these terminally ill patients, he said.
That's "an unfortunate decision," said Dr. Peter Lurie of the consumer advocacy group Public Citizen, which had urged the FDA to reject Iressa's sale until questions about the toxicity and true benefit were settled.
He questioned if some U.S. deaths thought to be from lung cancer really were Iressa-caused ILD.
Conversely, some studies now under way in Japan should help clear up exactly how doctors there classify ILD, to see if it's being overdiagnosed, said AstraZeneca spokeswoman Mary Lynn Carver.
AstraZeneca plans to begin shipping Iressa to pharmacies in two weeks, and expects the retail price to be $1,900 a month.
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