Complete Response of Metastatic Androgen Receptor–Positive Triple Negative Breast Cancer to Bicalutamide: Case Report and Review of the Literature
According to this article and case report, complete response could be obtained in some triple negative breast cancers when the patinet is treated with a common drug used for prostate cancer called Bicalutamide.
Bicalutamide is a androgen receptor antagonist and it seems that 10% to 32% of the triple negative breast cancers have androgen receptors that can be targeted by Bicatulamide.
Breast cancer is a heterogeneous disease and tumors with similar clinical stage and pathology may have markedly different outcomes. Breast cancer subtypes can be identified through gene expression profiling that convey different clinical, biologic, and therapeutic implications.1 Triple-negative breast cancer (TNBC) is defined by the lack of expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal factor receptor 2 (HER2). This subtype represents 15% to 20% of all breast cancers2 and is associated with the worst outcome of all subtypes, with greater tendency to distant recurrence in general and visceral metastases in particular.3,4 Recently molecular stratification of TNBC has been described, which could have treatment implications.5,6 Approximately 10% to 32% of TNBC have androgen receptor (AR) expression.7 As AR signaling has been shown to be intact in such patients,8,9 AR blockade could be a potential endocrine treatment.
Bicalutamide is a nonsteroidal antiandrogen, which competitively inhibits the binding of androgens with the AR.10 It is widely used in the treatment of locally advanced and metastatic prostate cancer either as monotherapy or combined with a gonadotropin-releasing hormone agonist.11,12 We present a case of a heavily pretreated woman with metastatic TNBC and AR expression who achieved a complete clinical response after 4 months of treatment with the AR antagonist bicalutamide.