The National Cancer Institute (search) said on Monday it halted a trial it was sponsoring of AstraZeneca PLC cancer drug Iressa (search) because the medicine was not increasing patients' survival.

The interim results of the NCI study mirror findings of another trial disclosed in December which also found Iressa did not improve survival rates of lung cancer patients.

The NCI was testing Iressa in lung cancer patients who had completed chemotherapy to see if the drug would prolong their lives. But in a statement, the NCI said interim analysis failed to show improved survival rates.

Iressa was approved by the Food and Drug Administration in 2003 as a treatment for lung cancer patients who had failed standard therapy. As part of Iressa's expedited review process, AstraZeneca was required to complete additional tests.

Last December, London-based AstraZeneca announced that a trial found that Iressa did not help lung cancer patients live longer. After the results were announced, AstraZeneca withdrew its application to sell Iressa in Europe and stopped actively marketing the drug in the United States.

Last year, Iressa sales totaled $389 million. After AstraZeneca announced Iressa failed to prolong life, Friedman, Billings, Ramsey analyst David Moskowitz slashed his estimate of the drug's sale for this year to $190 million, from $440 million.

Moskowitz said there was still hope that despite the December announcement, Iressa would be a useful drug. But he said the NCI's move "cast a little bit of doubt on that."

Iressa's outlook is further clouded because Tarveca, a competing product marketed by Genentech Inc. and OSI Pharmaceuticals Inc. has been shown to prolong the lives of lung cancer patients.

Shares of AstraZeneca, whose best-selling drug is acid-reflux medicine Nexium, fell 22 cents to close at $43.20 Monday on the New York Stock Exchange. They have traded between $34.72 and $49.51 the last 52 weeks.