Drug combination helps certain breast cancer cases

WASHINGTON (Reuters) - A cocktail of three targeted drugs may help women with a specific type of breast cancer far better than any of the drugs used alone, U.S. researchers reported on Tuesday.

A study in mice showed that using the three drugs, along with a breast cancer drug called tamoxifen, helped completely clear tumors, and they did not come back. In contrast, tumors came back after several weeks if a single drug was used.

The type of breast cancer is called HER2-positive breast cancer, which accounts for about a quarter of human breast cancer cases.

"For the first time, we were able to cure mice of a very aggressive human breast tumor," said Dr. Rachel Schiff of the Baylor College of Medicine in Houston, who led the study.

Schiff and colleagues tested an experimental drug called pertuzumab and trastuzumab, sold under the brand name Herceptin. Both are made by Genentech, majority owned by Roche AG.

The third drug was gefitinib, sold by AstraZeneca under the brand name Iressa.

All the drugs are monoclonal antibodies -- engineered human immune system proteins precisely designed to attack certain aspects of tumors.

Writing in the Journal of the National Cancer Institute, the researchers said their findings supported the idea that HER2-positive tumors eventually acquire resistance to any one of the drugs, but that attacking them on several fronts can stop this evolution.

"Now we have effective treatment, and survival is markedly improved," said Dr. Grazia Arpino, who worked on the study.

Cancer chemotherapy has long used the cocktail approach, but using several targeted therapies may cause fewer side-effects, because the drugs affect only tumors and not healthy cells.

"When you go after a specific target in a patient's tumor, the treatment is likely to be more effective and less toxic," Schiff said in a statement.