Androgen-receptor: a new drug target in breast cancer

9 May 2009

New results, presented at the IMPAKT Breast Cancer Conference in Brussels, may help scientists develop treatments for women with a type of breast cancer that currently does not respond to targeted therapies.

Although most people think of breast cancer as a single disease, doctors have recently come to understand that it is actually comes in a variety of different "subtypes" that diagnosed based upon the presence three "receptors" found on cancer cells: oestrogen receptors, progesterone receptors and human epidermal growth factor receptor 2 (HER2).

Effective treatments have been developed to target each of these receptors, but some cancers are oestrogen receptor-negative, progesterone receptor-negative and HER2-negative, and are known as "triple negative" breast cancers. Triple-negative tumours generally do not respond to receptor-targeted treatments.

In recent years, scientists have begun looking for new targets in these "triple-negative" cancers. One that has been identified is the androgen-receptor.

Dr. Sibylle Loibl and colleagues reported that in a group of 682 patients with primary breast cancer, almost half expressed androgen receptor.

The patients they studied had taken part in a trial where they received treatment with three chemotherapy drugs. Among those with triple-negative tumours, the researchers found that expression of the androgen receptor was correlated with a lower likelihood of an effective treatment.

"This group has looked for the expression of androgen receptor in breast cancer and found a sub-group of the population who do express it, and have shown that these patients respond worse to chemotherapy than those whose tumours do not express androgen receptor," said Professor Jose Baselga.

He noted that a clinical trial is currently underway to try and target the androgen receptor in breast cancer. "I think we are seeing the birth of a new concept in breast cancer-the androgen-receptor-positive breast cancer," Professor Baselga said. "This is an important development in finding new targets that we can attack with new drugs in the future."

Watch an interview with Dr. Sibylle Loibl on ecancertv here.