Approximately 10 - 15% of
breast carcinomas (BCs) are known to be 'triple-negative (
TN) receptor' (i.e., not expressing ER or PR and not exhibiting overexpression and/or gene amplification of HER2-neu). Triple-negative BCs comprise approximately 85% of all basal-type tumours. Classically, basal-like BCs have been characterised by low expression of ER, PR, and HER2 neu and high expression of CK5, CK14,
caveolin-1, CAIX, p63, and EGFR (HER1), which reflects the mammary gland basal/myoepithelial cell component. Although there is no standard first-line
chemotherapy regimen for metastatic TN BCs,
anthracycline- and
taxane-containing regimens are acceptable treatments. A large number of agents, including
DNA-damaging agents, EGFR inhibitors,
antiangiogenic agents and novel
taxane formulations are currently being tested in clinical trials for first-line and pretreated patients. Limited experiences with
platinum salts,
poly(ADP-ribose) polymerase (
PARP) inhibitors,
cetuximab,
bevacizumab and
ixabepilone have been published in recent years and will be reported. Novel immunohistochemistry analysis for identification of basal like/TN phenotype are awaited to correctly select this population. The clinical trials investigating new agents have to be designed for a specific (and possibly large) subset of patients with BC. In the future, a gene array platform with greater sensitivity for distinguishing the various BC subtypes, as well as having the power to predict the molecular biology of the disease, will be an indispensible tool for treatment selection. Currently, treatment of TN BC is more empirical than evidence-based. The cornerstone of treatment is
chemotherapy, but in the near future, novel target agents will emerge as possible partners.