Androgen Receptor May Contribute to Some Cases of Triple-Negative Breast Cancer
by C.H. Weaver M.D.
Some triple-negative breast cancers test positive for the androgen receptor and may respond to treatment with an anti-androgen drug. These results—from a Phase II clinical trial—were presented at the 2012 annual meeting of the American Society of Clinical Oncology.
Androgens are hormones such as testosterone. Although androgens are often considered to be “male” hormones, they are also found at lower levels in women.
Androgens contribute to the growth of certain types of cancer (most notably, prostate cancer), and drugs that block the effects of androgens are commonly used in prostate cancer treatment.
Some breast cancers have also been reported to contain androgen receptors, and could respond to anti-androgen treatment. Although androgen receptors tend to be more common in women with estrogen receptor-positive breast cancer than in women with triple-negative breast cancer, identifying and targeting the androgen receptor could benefit a subset of women with triple-negative breast cancer.
To evaluate this question, researchers conducted a Phase II clinical trial among more than 400 women with metastatic breast cancer that was estrogen receptor-negative and progesterone receptor-negative (ER-/PR-). All of the cancers were tested for androgen receptor, and those that were positive were treated with bicalutamide. Bicalutamide is an anti-androgen drug that is commonly used in the treatment of prostate cancer. Of the cancers treated with bicalutamide, only one was HER2-positive (the rest were triple-negative).
- 12 percent of these ER-/PR- breast cancers tested positive for the androgen receptor.
- Among the patients treated with bicalutamide, 21 percent had cancer that remained stable for at least six months.
Although research on androgen receptors in triple-negative breast cancers is still at an early stage, these results suggest that anti-androgen drugs may provide a modest benefit for some women with this type of breast cancer.
Reference: Gucalp A, Tolaney SM, Isakoff SJ et al. Targeting the androgen receptor (AR) in women with AR+ ER-/PR- metastatic breast cancer (MBC). Presented at the 2012 annual meeting of the American Society of Clinical Oncology, June 1-5, 2012, Chicago, IL. Abstract 1006.