The study hypothesis is that the new drug EndoTAG-1 will improve tumor volume reduction as measured by Magnetic Resonance Imaging when added to a standard chemotherapy regimen of weekly paclitaxel. This is a prospective single-center study that will investigate the activity of EndoTAG-1 + paclitaxel combination therapy in patients with HER2-negative breast cancer that are candidate for receiving chemotherapy before surgery (neoadjuvant chemotherapy).