Targeting the androgen receptor in triple-negative breast cancer

What is it about?

There are many subtypes of breast cancer, and they do not all behave the same. Some types are more aggressive, grow faster, are more likely to metastasize, while other types are less so. One way of grouping breast cancer into subtypes is by testing the biomarkers present in a tumor. The classical biomarkers are estrogen receptor, progesterone receptor, and HER2, and they are routinely tested for all patients. Presence or absence of each of these three biomarkers can indicate which drug will work well against the tumor, as well as help clinicians estimate the likelihood of recurrence or metastasis. Using these three biomarkers provides limited information, however - there is still variation within each subtype, especially in the subtype of triple-negative breast cancer. Presence or absence of an additional biomarker, the androgen receptor, may provide supplementary information. In this article we review the evidence supporting the value of androgen receptor status within a tumor; does androgen receptor positivity or negativity help physicians further narrow down which patients will respond well to a specific drug? Does androgen receptor status help predict which patients are likely to recur and therefore need more extensive treatment? We discuss results and limitations of pre-clinical and clinical trials where drugs that can modulate the androgen receptor are being used to target triple-negative breast cancer.

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Why is it important?

Androgen receptor's role in breast cancer has received increased attention in the last decade, and several drugs are currently being investigated as a way to modulate a tumor's levels of androgen receptor. Androgen-dependent tumors may potentially be eliminated by these anti-androgen drugs, used either alone or in combination with traditional chemotherapy drugs. Determining the significance of androgen receptor positivity/negativity may help refine breast cancer classifications and help patients and physicians decide what treatment is indicated.

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