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Medline ® Abstract for Reference 78

of 'Epidemiology, risk factors and the clinical approach to ER/PR negative, HER2-negative (Triple-negative) breast cancer'

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Phase II trial of bicalutamide in patients with androgen receptor-positive, estrogen receptor-negative metastatic Breast Cancer.
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Gucalp A, Tolaney S, Isakoff SJ, Ingle JN, Liu MC, Carey LA, Blackwell K, Rugo H, Nabell L, Forero A, Stearns V, Doane AS, Danso M, Moynahan ME, Momen LF, Gonzalez JM, Akhtar A, Giri DD, Patil S, Feigin KN, Hudis CA, Traina TA, Translational Breast Cancer Research Consortium (TBCRC 011)
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Clin Cancer Res. 2013 Oct;19(19):5505-12. Epub 2013 Aug 21.
 
PURPOSE: Patients with hormone receptor-negative breast cancer generally do not benefit from endocrine-targeted therapies. However, a subset with androgen receptor (AR) expression is predicted to respond to antiandrogen therapies. This phase II study explored bicalutamide in AR-positive, estrogen receptor (ER), and progesterone receptor (PgR)-negative metastatic breast cancer.
EXPERIMENTAL DESIGN: Tumors from patients with ER/PgR-negative advanced breast cancer were tested centrally for AR [immunohistochemistry (IHC)>10% nuclear staining considered positive]. If either the primary or a metastatic site was positive, patients were eligible to receive the AR antagonist bicalutamide at a dose of 150 mg daily. Clinical benefit rate (CBR), the primary endpoint, was defined as the total number of patients who show a complete response (CR), partial response (PR), or stable disease (SD)>6 months; secondary endpoints included progression-free survival (PFS) and toxicity. Correlative studies included measurement of circulating endocrine markers and IHC surrogates for basal-like breast cancer.
RESULTS: Of 424 patients with ER/PgR-negative breast cancer, 12% tested AR-positive. The 6-month CBR was 19% [95% confidence interval (CI), 7%-39%]for bicalutamide. The median PFS was 12 weeks (95% CI, 11-22 weeks). Bicalutamide was well-tolerated with no grade 4/5 treatment-related adverse events observed.
CONCLUSION: AR was expressed in 12% of patients with ER/PgR-negative breast cancer screened for this trial. The CBR of 19% observed with bicalutamide shows proof of principle for the efficacy of minimally toxic androgen blockade in a select group of patients with ER/PgR-negative, AR-positive breast cancer.
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Authors' Affiliations: Breast Cancer Medicine Service, Departments of Pathology, Biostatistics, and Radiology, Memorial Sloan-Kettering Cancer Center; Weill Medical College of Cornell University, New York; Dana-Farber Cancer Institute; Massachusetts General Hospital, Boston, Massachusetts; Mayo Clinic, Rochester, Minnesota; Georgetown Lombardi Comprehensive Cancer Center, Washington, District of Columbia; University of North Carolina at Chapel Hill, Chapel Hill; Duke University Medical Center, Durham, North Carolina; University of California, San Francisco Helen Diller Family Comprehensive Cancer Center, UCSF, San Francisco, California; University of Alabama at Birmingham, Birmingham, Alabama; and The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, Maryland.
PMID