Update on PARP Inhibition for Patients With Triple-Negative Metastatic Breast Cancer

Approximately 15% of breast cancers lack expression of oestrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptors (HER2).1 This triple-negative breast cancer (TNBC) is an aggressive disease: About 30% of patients will develop metastatic disease, whereby symptomatic visceral and brain metastases are common and the median survival is approximately 13 months.2,3 Treatment options for patients with metastatic TNBC are limited; chemotherapy is associated with a progression-free survival (PFS) of <4 months.4 Moreover, targeted therapies are not an option, since triple-negative tumours lack receptor expression required for currently available therapies. Thus, more effective treatments are clearly needed for patients with metastatic TNBC.