Targeted Breast Cancer Drug Shrinks Tumors

A new targeted cancer drug has been shown to shrink tumors in women with metastatic breast cancer after an average of seven other drugs, including Herceptin, failed.

The new drug, called T-DM1, combines Herceptin with a potent chemotherapy drug. It's a Trojan horse approach, where Herceptin homes in on cancer cells and delivers the cancer-killing agent directly to its target.

Tumors shrank in one-third of women with metastatic breast cancer given T-DM1, says Ian Krop, MD, of the Dana-Farber Cancer Institute in Boston. In another 12%, tumors stopped growing for at least six months.

The women remained cancer-free for an average of seven months -- results unheard of in patients this sick, he says.

All the women, who had breast tumors for an average of three years, had cancer that had metastasized, or spread to other parts of the body. They had been treated with an average of seven different therapies, including Herceptin, Tykerb, and Xeloda, and each had failed.

"This is the first study looking at women who have failed so many other treatments," Krop tells WebMD. "But we think these results are as good as we've ever seen is such a refractory [sick] population," he says.

The findings were presented at the San Antonio Breast Cancer Symposium.