Pharmaceutical giant AstraZeneca told an FDA committee this week that the failure of its last-chance cancer drug, Iressa, to significantly improve survival rates in a clinical trial was a surprise and that a review was underway to determine why the product didn't do better.
Iressa won Food and Drug Administration approval in 2003 for advanced lung cancer patients who had exhausted standard therapy after studies showed that it shrank tumors in some terminally ill patients. But approval, based on preliminary studies, came with a requirement that the drug be further tested.
In a follow-up trial, Iressa failed to produce an improvement that was statistically significant, prompting AstraZeneca to stop promoting the drug and to advise doctors that it had failed to live up to expectations for unknown reasons.
AstraZeneca told an FDA advisory committee, meeting this week to review several cancer drugs, that it was conducting a detailed analysis of the trial.
"The failure to reach statistical significance for survival in the overall population was completely unexpected," the company said in its report to the committee.
It went on to say that Iressa did produce responses in tumors and that some groups of patients did see benefits, notably people of Asian descent and nonsmokers.
In a separate report, a study appearing this week in the Journal of the National Cancer Institute found a gene mutation involved in the development of some lung cancers that is prevalent in nonsmokers with lung cancer. The gene mutation appears to increase a patient's sensitivity to Iressa. The same mutation also was found more commonly in women and patients from Japan.
The FDA advisory committee, which was not scheduled to take any action on whether Iressa should remain on the market, had asked the manufacturer to provide a report on its current studies of the drug.
London-based AstraZeneca said it didn't believe a decision on the commercial availability of the drug should be made until the completion of its analysis of the trial, which it expects to finish by May or June.
In the meantime, it has advised physicians about the lack of success and noted that alternative therapies are available. The company said it intended to continue to make Iressa available "as an option for patients who are deemed appropriate."
AstraZeneca shares closed up $1.38 to $41.34 on Thursday on the New York Stock Exchange.