Iressa shows promise for treatment of metastatic breast cancer when combined with hormonal therapy

Patients in the combination arm did have a higher rate of adverse events, but Cristofanilli notes that overall Iressa was very well tolerated.

"To see such a difference in such a small subset of patients was tremendously surprising," said Cristofanilli. "These findings show the possibility of adding a targeted therapy such as Iressa or others in the EGFR drug class to improve the benefit for hormonal therapy, giving another option for women who are hormone receptor positive, Her-2 negative with metastatic disease."

About 60 percent of women with breast cancer are hormone receptor positive and Her-2 negative, said Cristofanilli.

Iressa, a once-daily, oral tablet, was the first in a new class of anti-cancer drugs known as epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, to become commercially available. Iressa received FDA approval May 5, 2003 as a single agent treatment for patients whose advanced lung cancer has continued to progress despite treatment with platinum-based and docetaxel chemotherapy.

However, in 2005, after a large international study resulted in negative findings and reported numerous negative side effects, the drug's labeling was altered by the FDA. Only cancer patients who had already taken the medicine and whose physician believed it was helping them were allowed to receive the drug. No new lung cancer patients were given the drug after this time.

During this period, Iressa was being tested in clinical trials in a number of cancer types, including breast cancer. Other breast cancer trials studying Iressa, either as a single agent or when combined with chemotherapy, were mostly negative.

These negative findings impacted the accrual of the Arimidex-Iressa breast cancer study, said Cristofanilli. The study fell well short of its accrual goal of 174 women.

"Still, there's significant clinical relevance to our findings. Of course, I would advise that physicians not rush to put metastatic breast cancer patients who are hormone receptor positive and estrogen receptor negative on other drugs in this class that are readily available," said Cristofanilli. "Rather, this study should serve as a proof-of-concept. With our results, there should be a renewed interest in this class of drugs and hopefully follow-up studies in the adjuvant setting will be conducted."

The study was funded by AstraZeneca. Updated data will be presented Sunday, June 1 at 8:15 a.m. in the oral presentation, "Breast Cancer, Metastatic."

About M. D. Anderson

The University of Texas M. D. Anderson Cancer Center in Houston ranks as one of the world's most respected centers focused on cancer patient care, research, education and prevention. M. D. Anderson is one of only 39 Comprehensive Cancer Centers designated by the National Cancer Institute. For five of the past eight years, M. D. Anderson has ranked No. 1 in cancer care in "America's Best Hospitals," a survey published annually in U.S.News and World Report. Visit www.mdanderson.org for more information.