This is a prospective, randomized Phase IV study. Patients who progressed after one chemotherapy in the metastatic setting will be randomized 1:1 to one of the following treatment arms. Arm A. Eribulin 1.23 mg/m2 on days 1 and 8 q21d Arm B. Paclitaxel 80 mg/m2 on days 1, 8, and 15 q21d Blood draws for immune analysis will be performed before start of therapy on day 1 of cycle 1, on day 1 of cycle 2 (pre dose each) and on day 21 of cycle 4 (end of therapy) and assessed for the primary study aim. Patients will be treated under study conditions for a maximum of 4 therapy cycles.
After progression of disease after one chemotherapy, metastatic breast cancer patients will be randomized 1:1 to one of the following treatment arms:~Arm A. Eribulin Arm B. Paclitaxel~Blood draws for immune analysis will be performed before start of therapy, on day 1 of cycle 2 and on day 21 of cycle 4 (end of therapy) for the primary study aim. Patients will be treated under study conditions for a maximum of 4 therapy cycles.