TBCRC 011: Targeting the androgen receptor (AR) for the treatment of AR+/ER-/PR- metastatic breast cancer (MBC)

TPS122 Background: Patients with ER-/PR- MBC do not benefit from endocrine therapy. Doane et al. described a subgroup of ER-/PR- breast cancers with a gene expression profile similar to ER+ tumors but characterized by AR expression (Oncogene 2006). Farmer et al. identified an AR+ER-, non-basal-like group of breast tumors in a separate data set and termed them molecular apocrine breast cancer (Oncogene 2005). In vitro studies with the MDA-MB-453 cell-line, which is representative of this subtype, demonstrated AR-dependent growth and supported AR inhibition as a potential therapeutic approach for these patients (Doane et al., Oncogene 2006). We are testing the efficacy of the AR antagonist, bicalutamide (B) for patients with AR+/ER-/PR- MBC in a multicenter Phase II trial. Clinical trial registry #: NCT00468715. Methods: Patients with ER-/PR- (immunohistochemistry (IHC)