This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational intervention to learn whether the intervention works in treating a specific disease. Investigational means that the intervention is being studied.~The FDA (the U.S. Food and Drug Administration) has not approved atezolizumab for this specific disease but it has been approved for other uses.~Atezolizumab is a protein that affects the immune system by blocking the PD-L1 pathway. The PD-L1 pathway controls the body's natural immune response, but tumors can interrupt this pathway and partially resist or escape the immune system. By blocking the PD-L1 pathway, Atezolizumab may help the immune system identify and catch tumor cells.~Stereotactic radiosurgery (SRS) is a standard procedure used to treat patients with cancer in the brain. SRS uses many precisely focused radiation beams to treat tumors. It is not surgery in the traditional sense because there's no incision. Instead, SRS uses 3-D imaging to target high doses of radiation to the affected area with minimal impact on the surrounding healthy tissue. Like other forms of radiation, SRS works by damaging the DNA of the targeted (tumor) cells. The affected cells then lose the ability to reproduce, which causes tumors to shrink.~When given separately, atezolizumab and SRS, work in different ways to help stop cancer cells from growing and spreading. However, it is not known if giving atezolizumab and SRS at the same time will have a better effect than giving each treatment on its own. It is hoped that SRS treatment will damage cancer cells and make them more visible to the immune system.~The researchers conducting this study are testing to see whether giving SRS with atezolizumab may boost the body's immune response to cancer, and therefore improve upon the effects of either SRS or atezolizumab given alone.~In this research study, the investigators will measure the length of time that the participant receive this study intervention without the disease getting worse. The investigators will also look at how well the disease responds to atezolizumab and SRS as well as the safety of the combination.
This research study is studying the combination of a drug called atezolizumab and a radiation procedure called stereotactic radiosurgery (SRS) as a possible treatment for triple-negative breast cancer that has spread to the brain.~The interventions involved in this study are:~Atezolizumab~Stereotactic radiosurgery (SRS)