Stereotactic Body Radiation and Monoclonal Antibody to OX40 (MEDI6469) in Breast Cancer Patients With Metastatic Lesions

Patients will receive one of three different doses of SBRT depending on which cohort they are in. The doses are: Cohort 1: 15 Gy (central tumors 10 Gy); Cohort 2: 20 Gy (central tumors 15 Gy); Cohort 3: 20 Gy x 2 (central tumors 15 Gy x 2). In addition, all patients will receive three doses of MEDI6469. MEDI6469 is administered at 0.4 mg/kg IV over 60 minutes using in-line filter on Days 1, 3, and 5.