In a previous proteomic analysis of breast cancer patients responding to an epirubicin/docetaxel combination therapy, we found significant changes in the plasma levels of C1q and of several activation fragments of C3 and C4.19 In addition, an increase of HMGB1 was observed.20 In non-responders, however, the complement system as well as HMGB1 remained unaffected. Here, HMGB1 is linked to breast cancer.