Dual Therapy Helps Treat Aggressive Breast Cancer

Aggressive HER-2 positive metastatic breast cancer is difficult to treat. A recent study shows dual medication therapy offers new treatment options - and hope.

Researchers at The University of Texas MD Anderson Cancer Center have found that adding a drug to the standard therapy for HER2-positive metastatic breast cancer holds promise as an effective treatment. The targeted regimen, which added the medication Afinitor (everolimus) to Herceptin (trastuzumab), benefitted 34 percent of the women in the study.

Adding Afinitor to Herceptin helps HER2-positive metastatic breast cancer patients.

Too much of the protein HER2, a human epidermal growth factor, is found in about 25 percent of breast cancer tumors. This form of the disease is known as HER2-positive, and is one of the most aggressive to treat. Herceptin is the standard treatment therapy.

PK Morrow, M.D., assistant professor in the Department of Breast Medical Oncology and lead co-author of the study, says that about 30 percent of patients don't respond to the treatment, even when it's combined with chemotherapy. Metastatic cancers usually progress on this therapy.

When the treatment no longer works because of resistance to Herceptin, scientists have discovered that a cancer pathway described as PI3K/mTOR becomes active. Afinitor was shown to block this pathway.

Dr. Morrow says that the two drugs offer patients with metastatic HER2-positive breast cancer a chemotherapy-free option, which delivered benefits with less toxicity.

Two concurrent trials at MD Anderson and Dana-Farber Cancer Institute were the basis for the study. Participants included a total of 47 women with HER2-positive metastatic breast cancer that had progressed on Herceptin-based therapy. Nearly half of the patients had received at least two chemotherapy regimens.

Participants were given Afinitor daily and Herceptin every three weeks, and the study found:

• The dual therapy produced partial responses in 15 percent of patients
• Herceptin + Afinitor stabilized the disease in 19 percent of patients
• The total clinical benefit rate was 34 percent
• Median progression-free survival was four months
• Patients managed well with the side effects

This study was published in the Journal of Clinical Oncology.