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