Efficacy of antiandrogens in androgen receptor-positive triple-negative metastatic breast cancer: real-life data

Purpose Androgen Receptor (AR) + triple-negative breast cancer (TNBC) accounts for approximately 25% of all TNBC. Several trials using different antiandrogens (AA) found clinical benefit rates (CBR) ranging from 19 to 29%. The aim of this retrospective trial was to assess the clinical benefit of AA in real life. Methods Patients with metastatic AR + TNBC who have received at least one dose of an AA (abiraterone acetate, enzalutamide or bicalutamide) were eligible. Assessable patients received at least 4 weeks of AA and at least one tumor assessment. The primary end-point was CBR at 6 months defined as patients exhibiting an objective response (OR) or stable disease (SD) for at least 6 months. Results A total of 26 patients were eligible and 24 patients were assessable. Median age at initiation of AA was 70 years (range 50–90). Fifty percent exhibited liver and/or lung metastases. Median number of previous lines of chemotherapy was 3 (range 0–10). AA used were: abiraterone acetate (62%), enzalutamide (8%) and bicalutamide (30%). CBR at 6 months was 29% (7/24) with 5 OR (2 CR, 3 PR) and 2 SD. Fifty-seven percent (4/7) of patients with a 6-months CBR received AA in first line versus 18% (3/17) in later lines. Four patients had a clinical benefit > 12 months. There were no grade > 2 side effects. Conclusion Real-life efficacy of AA use in metastatic AR + TNBC are in line with data from published trials. A proportion of AR + TNBC patients benefit from AA and with some deriving long-term clinical benefit.