(Reuters) - Continuing to give AstraZeneca's drug Iressa plus chemotherapy to lung cancer patents whose disease has worsened after previously taking the medicine on its own does not provide any benefit.
Some doctors had hoped that extending the use of Iressa in combination with chemotherapy would help to keep cancers at bay, even when tumor cells had started to develop resistance to the drug.
But a clinical study presented at the European Society for Medical Oncology annual congress on Sunday found no statistically significant improvement in the length of time patients lived without their disease getting worse.
The Phase III study, involving 265 patients, tested Iressa plus chemotherapy to chemotherapy alone. It was sponsored by AstraZeneca.
Lead researcher Tony Mok of the Chinese University in Hong Kong said the result suggested doctors should not prescribe so-called EGFR tyrosine kinase inhibitor drugs like Iressa when patients' disease had progressed after first-line use of the drugs.
Data on whether patients had a better overall chance of survival in either arm of the study was inconclusive, Mok said, although there was a suggestion of improved survival in those who did not take Iressa. "This needs to be monitored very closely in future," he said.
Drugs like Iressa and Roche's rival lung cancer pill Tarceva have been on the market for several years and provide a valuable treatment option for some lung cancer patients with a certain genetic mutation.
That mutation affects around 10 to 15 percent of European and American patients with non-small cell lung cancer and 30 to 40 percent of those in Asia.
A new generation of targeted lung cancer drugs are now being developed to target a genetic mutation that helps tumors evade current treatments like Iressa and initial test results have been promising.
One of the new drugs is AstraZeneca's experimental product AZD9291. AstraZeneca believes its new-generation medicine could sell as much as $3 billion a year - considerably more than Iressa's sales of $647 million last year.
(Editing by Susan Thomas)
