Phase II Study With the Trifunctional Antibody Ertumaxomab to Treat Metastatic Breast Cancer Progressing After Endocrine Treatment

The purpose of the study is to demonstrate clinical efficacy of the investigational trifunctional bispecific antibody ertumaxomab for treatment of patients with HER-2/neu 1+ or 2+ (FISH-) expressing advanced or metastatic breast cancer (stage III b/IV) which has progressed after endocrine therapy. Ertumaxomab is a trifunctional bispecific antibody targeting Her-2/neu and CD3 on T cells. Trifunctional antibodies represent a new concept for targeted anticancer therapy. This new antibody class has the capability to redirect T cells and accessory cells (e.g. macrophages, dendritic cells \[DCs\] and natural killer \[NK\] cells) to the tumor site. According to preclinical data, trifunctional antibodies activate these immune cells, which can trigger a complex anti-tumor immune response.