The investigational product motesanib (Amgen) is a small molecule tyrosine kinase inhibitor with high efficacy against VEGFR and c-Kit kinases. C-kit has been detected in 12% of breast cancers, correlating with basal or triple-negative breast cancer. In addition, efficacy of the drug has been noted to PDGFRα, which is expressed in approximately 40% of breast cancers and is associated with aggressive disease, metastatic invasion and poor prognosis. Importantly, in more than half (56%) of these cases, the carcinoma cells bearing the receptors expressed the PDGF-A ligand, suggesting an autocrine loop and a cancer cell-autonomous process. Cancer cell-autonomous pathways are especially attractive as drug targets against metastatic breast cancer because they are expected to continue to be functional at metastatic sites, since they do not depend on stromal factors.