Drug Combinations Offer New Options for Advanced Breast Cancer

Article date: December 16, 2011

By Stacy Simon

Several studies presented at the 2011 San Antonio Breast Cancer Symposium (SABCS) offer hope of new treatment options to women with advanced breast cancer.

Anti-estrogen combination

In one of the studies, women taking a combination of anastrozole (Arimidex) and fulvestrant (Faslodex) lived more than 6 months longer than women who took the drugs one at a time. Both drugs are already used to treat breast cancer, but usually not together.

The study involved 707 postmenopausal women with hormone-receptor-positive breast cancer that had metastasized (spread to other parts of the body). In women with hormone-receptor-positive breast cancer, the female hormone estrogen promotes the growth of cancer cells.

Anastrazole works by stopping the body from making estrogen. Fulvestrant works by blocking estrogen’s effect on cancer cells.

Half the women in the study group received both drugs at the same time. The other half received the standard treatment, which is to start with anastrozole, then when the disease progresses, to switch to fulvestrant. The women who received the combination survived an average of almost 4 years. The women who received the standard treatment survived an average of almost 3 ½ years.

The National Cancer Institute and AstraZeneca, which manufactures both drugs, funded the trial.

Protein blocker

In another study, women who took the drug everolimus (Afinitor) with exemestane (Aromasin) delayed the worsening of their breast cancer for about 4 months longer than women who took only exemestane.

Everolimus is used to treat advanced kidney cancer and other cancers. It blocks a protein that is too high in cancer cells, leading them to grow and divide. Exemestane is used to treat postmenopausal women with hormone-receptor-positive breast cancer. It keeps their bodies from making estrogen.

The drug combination was tested in a clinical trial called BOLERO-2 that enrolled 724 postmenopausal women with hormone-receptor-positive breast cancer that had metastasized. Women treated with the combination had no worsening of their breast cancer for more than 7 months on average. Those who took just exemestane had no worsening of their breast cancer for about 3 months on average. The study was stopped early so that all the women could take the combination of drugs.

This study was presented at the SABCS and published online in the New England Journal of Medicine. It was funded by Novartis, which makes Afinitor.

HER2 Target

In a third study, combining 2 drugs with chemotherapy showed promise in a large, clinical trial against HER2-positive breast cancer that had metastasized. The combination led to an additional 6-month delay in a worsening of the cancer.

HER2 is a growth-promoting protein that can be present on the surface of the breast cancer cells. Breast cancers with too much of this protein tend to grow and spread more aggressively. About 1 of 5 breast cancer patients has too much HER2. A standard first-line treatment for this type of breast cancer is Herceptin, which targets HER2, given with the chemotherapy drug docetaxel.

More than 800 women with advanced breast cancer were enrolled in the trial, called CLEOPATRA. About half received the standard treatment and half received the standard treatment plus the experimental drug pertuzumab. Those who received all 3 drugs delayed a worsening of their breast cancer by an average of about 1 ½ years. Those who received the standard treatment delayed a worsening of their breast cancer by an average of about a year.

In addition, more women who received all 3 drugs had significant shrinkage of their tumors.

Genentech manufactures pertuzumab and Herceptin and funded the trial. The results of the study were presented at the SABCS and published online in the New England Journal of Medicine.

The SABCS conference attracts experts from all over the world and showcases the latest in breast cancer research. This year’s schedule focused on emerging treatments in hard-to-treat populations, including patients with metastatic breast cancer, and on new knowledge about prevention and risk.

Reviewed by: Members of the ACS Medical Content Staff

ACS News Center stories are provided as a source of cancer-related news and are not intended to be used as press releases.

Citations: A Phase III randomized trial of anastrozole versus anastrozole and fulvestrant as first-line therapy for postmenopausal women with metastatic breast cancer: SWOG S0226. Presented at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium, December 6 – 10, 2011 (presentation S1-1). First author: Rita S. Mehta, MD, University of California, Irvine Medical Center.

Everolimus in Postmenopausal Hormone-Receptor-Positive Advanced Breast Cancer. Published online December 7, 2011 in the New England Journal of Medicine. First author: Jose Baselga, MD, PhD, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston.

Pertuzumab plus Trastuzumab plus Docetaxel for Metastatic Breast Cancer. Published online December 7, 2011 in the New England Journal of Medicine. First author: Jose Baselga, MD, PhD, Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston.