Triple-Negative Breast Cancer Studies Reported at ASCO

Breast Cancer News
Erin Rowley, Writer and Content Coordinator

Findings on an androgen receptorinfo-icon inhibitor, maintenance chemotherapyinfo-icon were presented during Monday's sessions on triple-negative breast cancerinfo-icon

Studies presented at the 2015 meeting of the American Society of Clinicalinfo-icon Oncologyinfo-icon (ASCO) included several on triple-negative breast cancer. Below we report on a trial of enzalutamide, an androgen receptor inhibitor medicineinfo-icon, and a study of maintenance chemotherapy in people with early-stageinfo-icon, hormone receptorinfo-icon-negative breast cancer. 

Androgen Receptor Inhibitor

In breast cancer, we most often talk about estrogeninfo-icon, progesteroneinfo-icon and HER2 receptors. But another receptor, the androgen receptor, may play a role in breast cancer as well.

In what is now the largest breast cancer study of a medicine that targets the androgen receptor, researchers gave study participants – women with metastaticinfo-icon, androgen receptor-positive, triple-negative breast cancer – enzalutamide (Xtandi), an androgen receptor inhibitor FDAinfo-icon approved for use in men with prostate cancer. They also used a new test, called PREDICT AR, with the hope it would identify the participants who would most benefit from the treatment.

Lead researcher Tiffany A. Traina, MD, of Memorial Sloan Kettering Cancer Center, in New York City, reported that medianinfo-icon progression free survival was 8 weeks in participants whose cancers were PREDICT AR-negative, but 16.1 weeks in participants who were PREDICT AR-positive. This suggests that enzalutamide hormonal therapyinfo-icon has activity in triple-negative breast cancers, and the PREDICT AR correctly identifies people whose cancers would benefit from the treatment.

Data about overall survival, or OS, the time from start of treatment until death from any cause, is not yet available.

Because enzalutamide showed activity in AR-positive triple-negative breast cancers, it deserves further study, some ASCO attendees said.

Maintenance Therapyinfo-icon With Low-Doseinfo-icon Chemotherapy

Maintenance therapies are treatments that are given to help keep breast cancer from coming back after initial therapyinfo-icon. Hormonal therapies, such as tamoxifeninfo-icon and aromatase inhibitors, used in hormoneinfo-icon-positive breast cancer, are examples of maintenance therapies.

These researchers wanted to test a low-dose chemotherapy regimeninfo-icon in women with hormone-negative, early-stage breast cancerinfo-icon who had already had standard chemotherapy treatment. The regimen was given as pills for one year and was made up of the medicines cyclophosphamideinfo-icon (Cytoxaninfo-icon) and methotrexateinfo-icon. Researchers looked at breast cancer-free survival in that group and in a control groupinfo-icon of participants who received no further treatment after standard chemotherapy.

Lead researcher Marco Colleoni, MD, of the European Institute of Oncology in Milan, Italy, reported that though breast cancer-free survival was higher in the group that received the study medicine, especially among participants who had triple-negative, node-positiveinfo-icon breast cancer, it was not a statistically significantinfo-icon difference. That means the difference could be because of chance.

Check out our previous coverage of ASCO 2015, including studies presented on Saturday related to surgery and preventing hair loss and studies presented Monday related to hormone receptor-positive breast cancer. Don’t forget to join us for our annual ASCO webinar on Thursday, June 4.

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Hormonal Therapy