Activity of abiraterone in rechallenging two AR-expressing salivary gland adenocarcinomas, resistant to androgen-deprivation therapy

Androgen-deprivation therapy (ADT) has been reported to be active in androgen receptor (AR)-expressing, relapsed/metastatic (RM), salivary gland cancers (SGCs). Abiraterone, an inhibitor of androgen synthesis, has recently been approved as a second-line treatment in hormone-resistant (HR) prostate cancer (PCa) patients. Two patients with AR-positive HR-RM adenocarcinoma, NOS of the salivary glands have been treated with abiraterone. This is the first time that this agent has been reported to be active in tumors other than HRPCa. Immunohistochemical analysis showed overexpression of EGFR, HER2, and HER3 in both untreated primary tumors. Sequencing analysis revealed a TP53 nonfunctional mutation in one case and a PIK3CA-activating mutation in the other. In conclusion, second line activity of ADT in AR-expressing, adenocarcinoma, NOS of salivary glands further strengthens the pathogenic and therapeutic role of AR signaling in AR-positive SGCs.