nab-Paclitaxel for the treatment of aggressive metastatic breast cancer

Despite advances in early diagnosis, prevention, and treatment, breast cancer remains the second-leading cause of cancer-related deaths in women. The 5-year survival rate for patients with metastatic breast cancer (MBC) is just 24%. However, some forms of MBC appear to be more aggressive than others. Triple-negative breast cancer (TNBC; lacking overexpression of human epidermal growth factor receptor 2 [HER2] and expression of estrogen and progesterone receptors) and breast cancers that overexpress HER2 are the 2 biologically defined subtypes with the worst prognoses. Although a number of effective options have been developed for the treatment of HER2-overexpressing disease, TNBC remains a difficult-to-treat subtype. In addition to hormone receptor and HER2 status, multiple other factors are predictive of relatively poorer clinical outcomes, including visceral metastasis, short disease-free interval between the end of treatment for early-stage disease and diagnosis of MBC, and higher number of metastatic sites. There is an urgent need to improve therapy for patients with aggressive forms of breast cancer. Taxanes are considered among the most active classes of compounds against breast cancer. This review specifically examines the clinical trials in which nab-paclitaxel was used to treat patients with MBC and factors associated with poor prognosis.