Once treatment is completed, all subjects will return to the University of California at Los Angeles (UCLA) for regular follow-up visits to check on their health and outcomes. At visits both prior to and after treatment special blood samples will be drawn to be studied by UCLA scientists to look into the basic science aspects of how durvalumab (MEDI 4736) and radiation work in the body. It is hoped that we will learn more about the basic safety and science of durvalumab (MEDI 4736) combined with Stereotactic Ablative Body Radiotherapy (SABR) vs. SABR alone, while extending the life and quality of life of these subjects.