Curtailed Lung Cancer Drug Enhances Breast Cancer Therapy

Although Iressa’s use to treat advanced lung cancer was restricted after warnings were added to its labeling, it has shown effectiveness with hormonal therapy against breast cancer.

A Phase II trial found women who received AstraZeneca’s Iressa (gefitinib) and Arimidex (anastrozole) had 14.5 months of progression-free survival compared with 8.2 months in women who did not receive Iressa — a 45 percent reduction in risk, according to the M.D. Anderson Cancer Center, where the study was conducted.

The trial also found 47 percent of women on the combination had stable disease for more than 24 weeks and 49 percent had a clinical benefit. In contrast, 22 percent of the women taking only Arimidex had stable disease for more than 24 weeks, and 34 percent had a clinical benefit.

Patients in the combination arm had a higher adverse event rate, but Iressa was well tolerated overall, according to principal investigator Massimo Cristofanilli.

Cristofanilli noted this trial is the first positive study of an epidermal growth factor receptor tyrosine kinase inhibitor for breast cancer. Its findings provide another option for women who are hormone-receptor positive and HER-2 negative — approximately 60 percent of women with breast cancer, he said. But he advised physicians not to rush to put these patients on drugs in the class.

The trial was funded by AstraZeneca, which did not comment by press time on its next steps for Iressa.