A Phase II Study of MDX-010 in Patients With Stage IV Adenocarcinoma of the Breast

Inclusion Criteria:

- Provide written informed consent

- diagnosed with Stage IV adenocarcinoma that has progressed despite previous therapy

- at least 18 years of age

- measurable disease defined by RECIST

- must discontinue any alternative therapy used to treat breast cancer at least 4 weeks
prior to enrollment and agree to not use such therapies during the duration of the
study (patients may continue to receive tamoxifen, bisphosphate therapy and
trastuzumab)

- prior radiation must be completed at least 4 weeks prior to enrollment

- ECOG performance status of 0-2

- Negative pregnancy test

- Screening lab values must be met

Exclusion Criteria:

- must be disease free from other cancers for at least 5 years

- symptomatic or untreated brain metastases

- active or history of autoimmune disease

- active HIV, HTLV, HBV or HCV infection

- concurrent medical condition requiring the use of systemic corticosteroids, must be
discontinued at least 4 weeks prior to enrollment

- prior therapy with anti-CTLA-4 antibody

- significant organ compromise, uncontrolled heart, liver, lung, or renal disease or
other serious illness

- pregnancy or nursing