An open-label, non-randomized, uncontrolled, one-stage, phase II study evaluating the efficacy and safety of the investigational trifunctional bispecific antibody ertumaxomab (anti-Her-2/neu x anti-CD3) for the treatment of hormone therapy refractory advanced or metastatic breast cancer tumours (stage IIIb or IV) which are known to express HER-2/neu (1+ or 2+/FISH negative).Ertumaxomab will be administered at 7 day intervals by constant rate 3 hour intravenous (i.v.) infusions according to the following sequential dose schedule: 10 µg (day 0) and thereafter 100 µg flat doses once every 7 days (± 1 day) for a maximum of up to 12 weeks or until disease progression or any other unacceptable toxicity.
