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Failed Lung Cancer Drug May Fight Breast Tumors

Iressa showed promising results in preliminary trial

MONDAY, May 16, 2005 (HealthDay News) -- The lung cancer drug Iressa may one day have a role to play in treating breast cancer patients.

Giving Iressa (gefitinib) to women with early breast cancer before surgery could shrink the tumor, claims a small study appearing in the May 17 online issue of The Lancet Oncology.

The findings are unlikely to translate into gains for women any time soon, however, experts say.

"This is a proof of concept that there might be clinical activity with this drug, and that's of interest," said Dr. Harold Burstein, a member of the breast oncology center at Dana-Farber Cancer Institute in Boston. "But it's certainly nothing that obviously changes the natural history of the disease or improves clinical endpoints such as helping patients have better surgical choices."

"It's an interesting observation, but we can't say it leads to something women should be doing tomorrow," added Dr. Len Lichtenfeld, deputy chief medical officer at the American Cancer Society.

Iressa was initially developed by drugmaker AstraZeneca as a treatment for lung cancer, but it failed to meet expectations. The National Cancer Institute ended its Phase III clinical trials of the drug just last month because it failed to prolong patients' lives. The company, which funded this trial, seems to be looking for alternate applications for the drug.

The majority of breast cancers are estrogen receptor-positive. Within this category, tumor cells that test positive for another receptor, epidermal growth factor receptor (EGFR), have a worse prognosis.

Often these women are treated with hormones before surgery to shrink the tumors. However, that therapy is not always effective and, when it is, it takes a long time to work. Chemotherapy is another option, but it can come with nasty side effects.

The authors of the current study speculated that inhibiting EGFR with Iressa while simultaneously administering a second type of drug -- called an aromatase inhibitor -- to lower the amount of estrogen in the body might be of therapeutic benefit.

The study involved 56 postmenopausal British women with breast cancers that were both estrogen receptor-positive and positive for EGFR. The women were recruited from hospitals in London.

The investigators assigned the women either Iressa plus Arimidex (anastrozole, an aromatase inhibitor) or Iressa plus a placebo for four to six weeks before surgery.

Tumor size was reduced by 30 percent to 99 percent in 12 of 22 women assigned the combination therapy, and in 14 of 28 women assigned Iressa and the placebo alone. The effect began to show up within four weeks of starting the medications, the researchers say.

Both treatment regimens also inhibited EGFR, they add.

The study authors believe this approach might encourage tumor shrinkage, which in turn might mean less extensive surgeries for patients.

For the time being, however, the main impact of this trial may be as a "gatekeeper" study, providing a rationale for further research.

"We are always looking for ways to bring new therapies to bear, to help breast cancer patients do better," Burstein said. "These are provocative data suggesting that the EGFR pathway may be valuable in controlling cancers, and certainly warrants further study."

More information

The National Cancer Institute has more on breast cancer.

SOURCES: Harold Burstein, M.D., Ph.D., member, breast oncology center, Dana-Farber Cancer Institute, and assistant professor, medicine, Harvard Medical School, both in Boston; Len Lichtenfeld, M.D., deputy chief medical officer, American Cancer Society; May 17, 2005, The Lancet Oncology online
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