Study of CR011-vcMMAE to Treat Locally Advanced or Metastatic Breast Cancer

Main Inclusion Criteria:

* Females with confirmed breast cancer
* Age ≥ 18 years
* Eastern Cooperative Oncology Group (ECOG) Performance Status 0 to 2
* Locally advanced or metastatic disease who have received at least two prior chemotherapeutic regimens for breast cancer, as follows:

  * At least one regimen must have been for locally advanced or metastatic disease
  * Subject must have received an anthracycline, a taxane, and capecitabine in any combination unless the subject was intolerant to or not a candidate for any of these agents
  * Hormonal therapy, biologic therapy (such as trastuzumab or bevacizumab), or immunotherapy do not count as one of the 2 regimens
  * Subjects with HER2/neu overexpressing tumors must have been treated with trastuzumab except in situations where the subject was intolerant to or not a candidate for trastuzumab
* Documented progressive disease within 6 months of the last regimen
* Adequate bone marrow, renal and liver function
* Signed informed consent

Main Exclusion Criteria:

* Chemotherapy, radiation, hormonal therapy, or bevacizumab within two weeks, or trastuzumab or investigational therapy within three weeks before treatment start
* Neuropathy \> NCI-CTCAE Grade 1
* Active brain metastases.
* New York Heart Association class III or IV heart disease
* Unstable angina
* Uncontrolled arrhythmia
* A marked baseline prolongation of QT/QTc interval
* Pregnant or breast-feeding women, and women of childbearing age and potential who are not willing to use effective contraception