Background: Androgen receptor (AR) upstreams complex signaling pathways that
regulate cell proliferation and contribute to breast tumorignensis. Several clinical trials were initiated
to investigate the clinical relevance of targeting AR especially in hormone-receptor-negative
Methods: The search was performed in PubMed and the meeting libraries of ASCO, ESMO,
SABCS, ImpakT congresses from January 2005 to July 2017. The following key words were
used: Breast cancer, Androgen receptor, androgen agonist/antagonist, Flutamide, Abiraterone, Bicalutamide,
Enzalutamide, Enobosarm, selective androgen receptor modulator.
Results: Screening of title/abstracts yielded a total of 20 relevant results. Of those, twelve studies
were found eligible: eleven clinical trials along with one case report. Response rates ranged from
0 to 12% while clinical benefit rates reached up to 35% in 2 studies (with enzalutamide and enobosarm).
Progression-free survival ranged from 2.8 to 4.5 months. The most widely used cutoff
for AR expression was 10%. High expression of AR was associated with more clinical benefit.
Regarding safety, anti-androgens were generally well tolerated with hot flushes, elevated transaminases
and fatigue being the most commonly reported across all agents.
Conclusion: Androgen receptor pathway targeting in advanced breast cancer remains a valid option
with reasonable clinical benefit in non-selected patients. Future studies are needed to define
an AR addicted cohort with better responses and outcome.