Breast cancer is the most frequently diagnosed cancer in women worldwide. In 2012, it was estimated that 1.7 million new cases of breast cancer were diagnosed worldwide, and 522,000 women died of the disease.1,2 Only ≈ 5% of patients are initially diagnosed with metastatic disease; however, about 30% of women treated for early-stage breast cancer will develop metastatic disease.3,4 Metastatic breast cancer is a heterogeneous disease and is generally considered incurable.4 Treatment choice is based on clinical, pathological, and molecular factors. For patients with hormone receptor (HR)–positive disease, the choice of hormone therapy depends on pre- or post-menopausal status as well as prior use and effectiveness of hormonal therapies. However, de novo or acquired resistance to endocrine therapy occurs.5 Systemic chemotherapy remains a crucial component of treatment regimens.4 Chemotherapy agents are appropriate for most patients with metastatic disease, including those with HR-negative disease with extensive visceral involvement, HR-positive disease after failure of hormone-directed therapy, human epidermal growth factor receptor 2 (HER2)–positive disease, and HR-negative/HER2-negative disease. The large number of available recommended therapies makes its management complex and thus represents a high unmet medical need.
The safety and efficacy of the agents and/or uses under investigation have not been established. There is no guarantee that the agents will receive health authority approval or become commercially available in any country for the uses being investigated