Selective Androgen Receptor Modulator in a Patient With Hormone-Positive Metastatic Breast Cancer

Androgen receptors (ARs) are highly coexpressed in estrogen receptor (ER)-positive breast cancers. Their role in breast tumorigenesis has been postulated, but the mechanism is not yet well-characterized. Steroidal androgens were previously used as an anticancer strategy but fell out of favor because of toxicity and the discovery of alternative therapies. Recent attempts to modulate androgen pathway signaling have focused on AR inhibitors. This report discusses a case using a well-tolerated selective AR modulator to treat a highly pretreated patient with ER-positive breast cancer, which resulted in a durable partial response.