ROCKVILLE, MarylandThe Food and Drug Administration (FDA) has granted
accelerated approval to Iressa tablets (gefitinib, AstraZeneca) as
monotherapy for the treatment of advanced non-small-cell lung cancer (NSCLC)
in patients whose disease has progressed despite treatment with
platinum-based and docetaxel (Taxotere) chemotherapy.
The Oncologic Drugs Advisory Committee (ODAC) had recommended approval of
Iressa on September 24, 2002. However, the FDA delayed action on the
recommendation for 3 months to analyze new Japanese data that indicated
Iressa was associated with an unexpected and often-fatal rate of interstitial
lung disease (ILD).
As a condition of approval, Astra-Zeneca agreed to conduct three phase IV
postmarketing trials of Iressa ( see box ). Accelerated approval is
granted to drugs that have shown indications of benefit in serious or
life-threatening diseases over available therapies or, as in the case of
Iressa, in conditions for which no effective treatment exists.
"An essential part of our accelerated approval process is the further
study of the new treatment after it is on the market," said FDA commissioner
Mark B. McClellan, MD, PhD. "In the case of Iressa, studies are needed to
confirm clinical benefit, understand better which patients benefit, and
evaluate long-term safety."
Although the drug’s mechanism of action is not fully understood, Iressa
was designed to inhibit growth stimulatory signals by blocking several
tyrosine kinases, including one associated with the epidermal growth factor
receptor. This blocking results in an inhibition of cancer cell proliferation
and an increase in apoptosis. The drug is administered as a 250-mg tablet
taken once a day.
Phase II Trial
The FDA approved Iressa on the basis of findings from a phase II trial
that studied two doses of the drug in 216 patients who had previously failed
platinum-based and docetaxel chemotherapy. In reviewing the data, ODAC
concluded that the 10% Iressa response rate in these patients was reasonably
likely to predict clinical benefit, but told the FDA that symptom improvement
could not be adequately evaluated without a randomized, blinded study.