US regulators approved a new drug that in clinical trials delayed breast cancer progression in women no longer responding to trastuzumab (Herceptin), a drug effective against tumors with too much of a protein called HER-2. When given in combination with chemotherapy, the new drug, lapatinib (Tykerb), did a better job of curtailing cancer growth than did the chemotherapy alone.

"Today's approval is a step forward in making new treatments available for patients who have progression of their breast cancer after treatment with some of the most effective breast cancer therapies available," said Dr. Steven Galson, director of the Center for Drug Evaluation and Research at the US Food and Drug Administration (FDA). "New targeted therapies such as Tykerb are helping expand options for patients."

About 8,000 to 10,000 American women die from metastatic HER 2-positive breast cancer each year, the FDA said.

How It Works

Tykerb, among a class of drugs called kinase inhibitors, deprives tumor cells of signals they need to grow. But it differs from other cancer drugs in that it actually enters cells and blocks the function of the HER-2 protein, the agency said.

Tykerb, which comes in pill form, is made by GlaxoSmithKline, which funded the clinical trial.

The Study

The drug was tested in a trial involving 400 women with advanced or metastatic breast cancer that was HER-2 positive. Common side effects included diarrhea, nausea, vomiting and a rash. A small percentage of participants also had a decrease in heart function that may have been characterized by shortness of breath. This condition generally was reversible, the FDA said.

Some 20% to 25% of breast cancers have abnormally high levels of the HER-2/neu receptor and, as a result, are generally more aggressive. Herceptin blocks activity of the receptor by binding to the part of the receptor outside the cell. Tykerb, by contrast, binds to a part of the receptor inside the cell.

The clinical trial included a plan for an independent monitoring committee to analyze data at the halfway point to see if the benefits were larger than anticipated, in which case the committee would recommend the study be closed.

The monitoring committee made a unanimous recommendation to terminate the trial because the results were so encouraging.

Women in the combined therapy group had almost double the time of disease progression as did women receiving chemotherapy alone: 36.9 weeks versus 19.7 weeks.

Responding to the FDA's approval of Tykerb, Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, said, "The approval of Tykerb is a significant step forward because it once again demonstrates the promise of targeted therapies, where we take our understanding of how cancer cells work and apply that knowledge to new drug development. We now have a new drug that offers promise and hope to women who have a more aggressive form of breast cancer, where until very recently we had little to offer."

Better Breast Cancer Recovery

Women with breast cancer who walked for at least one hour a week were 20% less likely to die from breast cancer compared with those who didn't exercise at all.

Theory: Exercise lowers hormone levels, which suppresses cancer growth recurrence.

For maximum benefit: Women with breast cancer should walk or perform equivalent exercise, such as bicycling) a total of three to five hours per week.

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