Study of MDX-010 in Stage IV Breast Cancer

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